Session 4- Working with Java Conditional Statements | J… — Transcript

Okay, so in the last class, we have seen how to work with the different types of operators in Java. Now today, let's continue with some more important topics, some basics, control statements. So the next topic is control statements. Normally, when you write your Java program and when you're executing it, the statements will be executed top to bottom. Let's say if you have written 10 statements or 100 statements, the execution will always happen top to bottom. So each and every statement will be executed in a sequential manner. Let's say these are the different statements, and execution will happen like this. So each and every statement will be executed, right? But sometimes, if we want to execute specific statements based upon certain conditions, let's say now I want to execute only this particular statement based upon a certain condition, and I want to execute another set of statements based on another condition. That means every time you don't need to execute the same set of statements. So based upon the condition, we can also choose the statements which we want to execute. Okay, this is basically called controlling your statements. It means instead of executing each and every statement in your program, we can select a set of statements or group of statements, and we can execute only those group of statements based on a certain condition. Okay, this is one scenario. Another scenario is suppose I have a set of number of statements, and I want to repeat the same statements multiple times again and again based upon a certain condition. I want to repeat the same steps, same statements again and again multiple times. This is basically called a loop, and we can execute the same set of statements multiple times repetitively. We call it a loop, and we can execute a set of statements based upon a certain condition. This we can achieve by using conditional statements. So basically, we can control the execution of your program or execution of your code by using control statements. There are three kinds of control statements, and by using those control statements, we can control the execution of your program or execution of your code. So mainly, there are three kinds of control statements in Java. So the first type is conditional statements, conditional statements, conditional statements, and the second is looping or iterative statements, and the third is jumping statements. So these are the three kinds of control statements which we have. So what is the use of these control statements? We can control the execution of your program or can control the execution order of your program. That we can achieve by using conditional statements or looping statements or jumping statements. So we will discuss today conditional statements, mainly conditional statements, and of them, we'll discuss in the next sessions. So what are the conditional statements available in Java? So there are four types of conditional statements. Conditional statements, there are four types of conditional statements. One is only if condition, if condition. Second is if else condition. Third is nested if else, and fourth is switch case. So these are the four different conditional statements supported in Java. So the purpose of using the conditional statements is the same, but we will use these statements in different scenarios: if, if else, nested if else, and then we have a switch case statement. So these are the four different types of conditional statements supported in Java. So now we'll see practically how can we use these conditional statements and where we can use these conditional statements with different types of examples. So the first condition statement is if. So how to use this if condition? The syntax of if condition is like this: if, and here we put some condition, and if this condition is true, then whatever steps we want to execute or whatever statements we want to execute, we can keep those statements inside this block. So this is called syntax how to use if condition. So if this condition is true, then only these statements will be executed. If this condition is false, these statements will be ignored. These statements will not be executed. So this is only if condition. Let me show you how to use this, and there is no semicolon for if condition. Okay, if you need to put some condition, open bracket, closing bracket, and what are all statements you want to execute based on the condition, we can specify them inside this block. Now let me show you some example. Go to Eclipse, and this is our project which we already created. Now today is day four. Let's create a new package, day four, and click on finish. So how to use if condition, only if condition. So let's create a new class, and I'll name it as IfConditionDemo. Take this main method also, and then say finish. Okay, so now my requirement is, my problem statement is, for example, I will take a person's age as a variable. Let's say personAge equal to, let's say, 25. This is the variable I have created. Now my requirement is I want to check this person is eligible for voting or not. So according to my condition, if the person's age is greater than or equal to 18, he is eligible for voting. That I want to verify. Okay, so I have a simple variable created, personAge equal 25. Now I want to check this person is eligible for voting or not. So if you want to check this person is eligible for voting, simply we can check the condition if the person's age is greater than or equal to 18. We can simply say he is eligible for voting. But how can we verify that condition? How can we check this person's age is greater than or equal to 18 or not? So now we can write one conditional statement. So if condition can use if, in the bracket we can specify the condition. What is our condition? The person's age should be greater than or equal to 18. Then only he is eligible for voting. So here I'm taking that variable, whatever variable I defined, that is personAge, that should be greater than or equal to 18. So will it return true or false? What is that operator we have used here? Greater than or equal to, which is a relational operator, right? So what is relational operator will do here? It will compare the personAge is greater than or equal to 18 or not, and if it is greater than or equal to 18, it will return true. If it is not, return false. That means here we have to always specify a Boolean expression. Here we have to always write a Boolean expression which will return true or false. So if the condition is true, if the expression returns true, then we can specify the statements which we want to execute based on the condition. Here inside this bracket, I can say System.out.println eligible, eligible for voting. Like this, you can specify. Now this particular statement will execute only if this condition returns true. Only if this expression returns true, then only this statement will be executed. And if this statement is written false or if the expression is written false, the statement will not be executed. That means based on the condition, we are executing this statement. If the condition is true, execute the statement. If the condition is false, then don't execute the statement. Okay, for example, let's say I'm taking 25. 25 is greater than or equal to 18 or not? Yes, the condition is true. True. So if the condition is true, then obviously the statement will be executed. So when I execute, run as a Java application, so now we can see the output here. So statement is got successfully executed because the expression is true. Now I'll just make this as 15. Now the personAge is 15. 15 is greater than or equal to 18. Expression returns false. So if it is false, the statement should not be executed. Now when I run this code, you will not get any output in the console window. So no output because we are not specifying anything else other than the statement. So only one statement is specified, and this will be executed only if this expression returns true, right? So this is how we can simply use if condition. If t

and when you're executing it so the statements will be executed top to bottom let's say if you have written 10 statements or 100 statements so the execution will always happens top to bottom so each and every statement will be executed in sequential manner let's say these are the

different statements and execution will happen like this so each and every statement will be executed right but sometimes uh if we want to execute a specific statements based upon certain condition let's say now I want to execute only this particular statements based

upon certain condition and I want to execute another set of statements based off another condition that means every time you don't need to execute the same set of statements So based upon the condition we can also choose the statements which we want to execute okay this is basically

called uh controlling uh your statements means instead of executing each and every statement in your program we can select set of statements or group of statements and we can execute only those group of statements based on certain condition okay this is one scenario another scenario is

suppose I have set of number of statements and I want to repeat the same statements multiple times again and again based upon certain condition I want to repeat the same steps same statements again and again multiple times this is basically called as a loop and we can execute the same set

of statements multiple times repetitively we call it as a loop and we can execute set of statements based upon certain condition this we can achieve by using conditional statements so basically we can control the execution of your program or execution of your code by using control statements

there are three kinds of control statements and by using those control statements we can control the execution of your program or execution of your code so mainly there are three kinds of control statements are there in Java so the first type is conditional statements conditional

statements conditional statements and the second is looping or item ative statements and the third is jumping statements so these are the three kinds of control statements which we have so what is the use of these control statements we can control the execution of your program or can

control the execution order of your program that we can achieve by using conditional statements or looping statements or jumping statements so we will discuss today conditional statements mainly conditional statements and of them we'll discuss in the next sessions so what

are the conditional statements are available in Java so there are four types of conditional statements conditional statements there are four types of conditional statements one is uh only if condition if condition second is if else condition third is nested if Els and

fourth is is switch case so these are the four different conditional statements supported in Java so the purpose of using the conditional statements is same but we will use these statements the different scenarios if if Els nested if Els and then we have a switch case

statement so these are the four different type of conditional statements supported in Java so now we'll see practically how can we use these conditional statements and where we can use this conditional statements with the different type of examples so the first condition statement is

if so how to use this if condition the syntax of if condition is like this if and uh here we put some condition and if this condition is true then whatever steps we want to execute or whatever statements we want to execute we can keep those statements inside this block

so this is called syntax how to use if condition so if this condition condition is true then only these statements will be executed if this condition is false these statements will be ignored these statements will not be executed so this is only if a condition let me show you

how to use this and there is no semicolon for if condition okay if you need to put some condition Open Bracket closing bracket and what are all statements you want to execute based on the condition we can specify them inside this block now let me show you some example examp go to

eclipse and this is our project which we already created now today is day four let's create new package day four and click on finish so how to use if condition only if condition so let's create a new class and I'll name it as if condition demo take this main method also

and then say finish okay so now my requirement is uh my problem statement is for example uh I will take a person age as a variable let's say in person uncore age equal to let's say 25 this is

the variable I have created now my requirement is I want to check this person is eligible for o or not so according to my condition if the person age is greater than or equal to 18 He is eligible for OT that I want to verify okay so I have simple a variable created person age equal

25 now I want to check this person is eligible for V or not so if you want to check this person is eligible for what simply we can check the condition if the person age is greater than or

equal to 18 we can simply say he is eligible for order but how can we verify that condition how we can check this person age is greater than or equal to 18 or not so now we can write one

conditional statements so if condition can use if in the bracket we can specify the condition what is our condition the person age should be greater than or equal to 18 then only he is eligible for order so here I'm taking that variable whatever variable I defined that is

person uncore age that should be greater than or equal to 18 so will it return true or false this what is that operator we have used here greater than or equal to which is a relational operator right so what is relational operator will do here it will compare the personage is greater

than or equal to 18 or not and if it is greater than or equal to 18 it will returns true if it is not return false that means here we have to always specify a Boolean expression here we have

to always write a Boolean expression which will return return true or false so if the condition is true if the expression is return true then we can specify the statements which we want to execute based on the condition here inside this bracket I can say system. println eligible eligible for

p like this you can specify now this particular statement will execute only if this condition is return returns true only if this expression is returns true then only this state will be executed and if this statement is written false or if the expression is written false the statement

will not be executed that means based on the condition we are executing this statement if the condition is true execute the statement if the condition is false then don't execute the statement okay for example let's say I'm taking 25 25 is greater than or equal to 18 or not yes

the condition is true true so if the condition is true then obviously the statement will be executed so when I execute run as a Java application so now we can see the output here so statement is got successfully executed because the expression is WR true now I'll just make this as a 15 now the

personage is 15 15 is greater than or equal to 18 expression return false so if it is a false the statement should not be executed now when I run this code you will not get any output in the console window so no output because we are not specify anything else other than the statement so

only one statement be specified and this will be executed only if this expression is return returns true right so this is how we can simply use if condition if the expression returns true statement will be executed if the expression return false statement will not be executed

so this is how we can simply use if condition only if condition but if it is not true then what should happen we haven't specified that we haven't specified that suppose if the condition is false what should happen if the condition is true the statement will execute if the condition

is false what should happen that we haven't specified here so this is only if a statement we haven't specified any else this is only if a statement if the condition is true statement will execute if the condition is false state will not be executed that's it only if condition the

first one okay but sometimes we should also specify else part that means if the condition is not true then what should happen that also we have to include right so for that we use another statement if along with else if block along with else this is called a block you can put one single

statement here or you can put multiple statements also allowed in if condition you can keep single statement or multiple statements okay sometimes if the condition is false then what should happen that also we can specify in the else block so this is only if condition okay now how can we

use if and else block combinations so the syntax will be like this if we put one condition if the condition is true then the group of statements will be executed and and if this condition is false for example if this condition is false then we write another block called else block

like this so if the condition is true then these set of statements will execute if the condition is false then else block will execute inside the else block also we can write the statements okay now if the condition is true if block will execute if the condition is false then else

block will automatically execute this is alternate okay now this is called if else condition if else condition okay so how to use this ifs condition so let's say uh save this let me create another class suppose if condition is uh if condition return return

false so then what we should happen let me just rename it this is if El condition okay so this is a if else condition same program I'm taking the person age if person AG greater than or equal to 18 He is eligible for and if this condition is false then what we should do

else we have to write else Block in else block we can specify and what we can specify not eligible not eligible for what like this so based on the condition we are choosing the statements right if the condition is true if block will execute if the condition is false else block will execute

at a time only one block will be executed both will not be executed because the condition uh will return true or false right if it returns true if block will execute if returns false else block will execute now when I say 15 the condition is false the expression will return

false so obviously else block will execute okay so not eligible for either this one or this one only one block will be executed always okay so this is how uh we can use El okay so if condition and then else along with else and you should not put semicolon for if condition like this

okay for else also should semicolon only the statements which we have included inside this block we have to specify the statements okay so if and else block like this fine so sometimes you may have multiple statements inside this okay so here if you have a single statement you can put

multiple statements or single statements suppose if you have a single statement here the brackets are optional okay the curly braces are optional you can directly keep the statement inside with condition and here also if you have one single statement in the lse block these brackets are

optional okay so let me show you so currently I have single statement in every block right so what I will do is I'll try to remove the I will try to remove the C braces just observe this okay now just observe here I just try to remove the Carly press and here also I'll Remo

it okay so now just observe when I running this so you will get a not eligible for now I'll take another number 25 and you will get eligible forward so how come it is executing so that means if you have a single statement under the condition you no need to specify the curly braces

you can directly write under this so if the condition is true the statement will execute and if the condition is false else statement will execute so if you have a single statement you no need to put in the CRA but if you have a multiple statements you have to include them in

the curly braces okay so what I will recommend is even though if you have a single statement better to keep inser the curly brace why because you clearly know whether the statement is belongs to this condition or not so by seeing the code you will understand this particular block will

be executed based upon this condition okay so if you have a single statement curly braces are optional and if you have a multiple statements you should keep inside the curly places okay that is another one you can just remember this so This is called if else condition so if condition is

true if block will execute if the condition is false else block will execute at a time only one block of statements will be executed okay now let me show you one more example for if else condition so the first example we have already seen elig ible for V or not now the example

two so suppose we Define one number and we need to find out that number is even or odd number so we provide one number and that number we have to find even number or odd number through our program okay

so how to find out so normally if I ask you if I give some number like this let's say I've given 10 so if I ask you whether it is even number or odd number how we will tell how we will know whether

it is even number or odd number we will simply say it is an even number when you say five you can simply say which is an odd number but how we will know whether this is even number or not this

is even number and this is odd number so how we will know whether is even number or odd number so we have some mathematical calculation behind that right so if any number divided by by two returns zero as a remainder that is an even number okay for example let's say if I take any number let's

say 10 10 ided 2 returns zero as a remainder that is a even number right and 10 ided by two suppose 5 divided by two which is written one as a remainder so other than zero whatever remainer you

will get other than zero they all comes under odd numbers it can be one or it can be anything else right this is a mathematical calculation simply we can say so if you want to say a number is a even

number that number divided by two should return zero as a rem remainer and if you want to say a number is an odd number when it divided by number by two that should return non zero other than zero

you will get any number as a reminder that is an odd number that is a logic so now programmatically we have to find a number is even number or odd number okay and how can we find out so again based

on the condition if a number divided by 2 equal to Z if condition is true then we can say even number and if not we can simply say odd number so based on the condition we can check so how can we use if

Els condition here let me create a new class even or odd number so how to check a number is even number or odd number so what we can simply say first we'll take one number in number equal to 10

so I have taken I have defined one variable right so now we need to find this number is even number or odd number so how can we check if this number divided by two divided by two which is returning

zero and uh which operator we have to use here W equal to or equal to equal or equal to which one we have to use condition if number percentage two returns zero as a remainer we we have to compare

this the remainder whatever is written by this expression should equal to zero or not we want to compare so we have to use comparison operator that is double equal to right so if number percent two why we are using percentile instead of Slash because percentile operator will return reminder

right it is also division operator but it will return return the remainer that we want to check so number percent 2 equal to0 that means if this is true when this expression true if number percent Del to returns zero then this expression will returns true overal expression right Boolean

value will be return so if this condition is true then what we can simply say that number is even number okay that number is even number and other than zero okay you suppose this condition Falls whenever the remainder is non zero that means other than zero if it is return any other

value this condition become false so in that case what we can simply say it is a odd number that you can specify in else block else block we can say system. print odd number like this so at a time only one statement will be executed based on the condition so if the condition is true if

block will execute if the condition is false else block will execute so when I execute this it will say Java application even number so we can say 10 right so 10 is a even number let's say 15 15 now

condition is false so obviously else block will execute which is odd number okay so this is how we can simply use if else condition okay if FSE condition we can use now let me show you some more examples example

three we can practice so many examples like this is and number of examples you can find so now I want to check a number is positive negative or zero check a number is positive or negative or zero so if I provide a number as an input and the program should display whether that number

is positive number or negative number or zero so normally how can we check a number is positive negative or zero as per mathematical calculation how can we verify number is positive negative or zero how can we say on what basis we can say a number is positive negative or zero

positive negative or zero how can we find yes simple calculation right if any number which is greater than zero that is positive number right if any number if I take any number as a variable if that is greater than zero

obviously that is a positive number right and if the number is less than zero that is a negative number that is a negative number and if the number is equal to zero obviously that is a zero only right so we have multiple conditions here so far we have seen only one condition

one if condition so sometimes we have to write multiple if conditions multiple conditions we have to verify if the number greater than zero say POS POS if the number less than zero say negative if the number equal to zero then say zero so here we have to check multiple conditions if you have

only one condition then we can use only one if one statement one if statement here just like this if condition is true block will execute if the condition is false another block will execute only one single condition which we have here but if have a multiple conditions in case if we have

a multiple conditions then how we can specify that so let me show you one more example take another class positive or negative number okay so how can we specify the multiple conditions okay first of all let us take a number

in number equal to let's take zero first the number value is zero now we want to check which is zero or positive or negative okay so the what is the first condition if this number greater than zero if this number greater than zero then what we can say here it is positive number which is

positive number fine suppose if this number is not greater than zero so condition is false then we have to verify another condition right how to verify another condition we can write like this else if else if again one more condition number less than zero then what we can say here system

is a negative number it's a negative number even this condition is also false for example number is not negative less than zero then what we can specify the last option which we have that is zero only right so else here you can say system. out. zero like this so multiple conditions we can

also verify by writing multiple if conditions so if number greater than zero execute the statement if this condition is false else one more if condition else number less than zero execute this statement even this condition is also false then else last statement will be executed so else

block else block will always execute if none of the conditions are true okay if all of the if conditions are false finally else block will execute so here we only need to put another condition again you only need to write else if number equal to zero not needed because

obviously else block will execute after execution of these two statements after execution of these two conditions if both the conditions are written false then finally else block will automatically execute so if you have a multiple conditions you can also write like this else give one space and

then if so the structure will follow like this this is called uh if else later we can call it as a if else later so the syntax will be like this if condition one first condition okay else if they're not satisfied else one more condition if condition two and statements and even second

condition is not possible not returns true then again one more condition else if condition three you can put any number of condition like this even this is also not satisfied then else one more condition else if condition four like this and if all conditions are done so finally if none

of the conditions are becomes true finally you can write only one else blog like this this is called if else later if else later so this is the syntax which you have to use you can put any number of conditions if condition one is true statements will execute in this blog else another

condition is true then execute the statement even this condition is also false then third condition it will verify even third condition is false then fourth condition will verify even this is also false finally block will execute so like this you can put any number of levels

different levels and different conditions you can specify okay now let us test this code at a time only one block of statement will be executed so initial I say number equal to zero so when I say number value zero obviously it will return zero as an output now when I say 10 then is a positive

number which is greater than zero so when I execute it is written positive number so when I say minus 10 minus - 10 is a negative number so when I execute it is written negative number the second block is got executed okay so at a time only one block of statements will be executed

based on the condition we can control it okay now let me show you one more example so we can also use sometimes logical operators in the conditions okay so let me show you one more example example four so in example four uh is we want to find largest of three numbers largest of three

numbers or you can call anything okay largest of three numbers I want I will provide three numbers the program should find out which one is the largest number okay for example uh let's take three variable let's say a = to 10 B = to 20 C = to 30 like this now program should say C

is the largest number or if B is the larger then program should find out and say B is the largest number or a is the largest number okay so before writing the program so nor normally let us think

about the logic how can we find a largest number if I give these three numbers immediately we will say C is the largest number but how come you say C is the largest number on what basis you are

saying C is the largest number do you have any uh mathematical thing here calculation to say which one is the largest number how we are saying actually we comparing each number with other numbers right so for example if a greater than b okay a greater than b and also a greater than C

then we are saying a is the largest number right this is a condition or not first we are taking one number we comparing with the rest of the two numbers if this number is greater than rest of two numbers obviously that is the largest number same we are repeating for other numbers also for

example if I take b b is greater than a a and also B greater than C then we are saying what B is the largest number B is a largest number same thing we are repeating for C also if C greater than a and C

greater than b also then obviously C is a largest number so based upon certain condition we are saying after comparison we are seeing each number we are comparing with other numbers so if that number is if the particular number is greater than other two numbers we are saying that is a largest

number or which a greater number so these are the actual conditions now the same conditions we have to apply in your programming also so if you want to say which one is the largest number we have to use multiple conditional statements okay and one if condition we can put multiple also right so

this we can achieve uh by writing multiple if Els conditions so let's see how can we implement this practically so let's create a new class and here I'll say largest of three numers take this main method and say finish okay same logic we will try to apply

here I keep this so that we can understand the conditions okay these are the three conditions to say largest of three numbers we have to verify these three conditions okay I put this in the comment so that you can understand the logic now let us try to implement this first

of all we need three numbers let's create three different variables int a = 10 comma B = 20 comma C = 30 now I have taken three numbers three variables now I want to find out which one is

a largest number so first let us compare a with b and c okay what is the first condition we have to check a greater than b and a greater than C then we will say a is a largest number right so what we

can do it here is first condition if a greater than b this is one condition another condition is what a greater than C both the conditions should be true then only we can say a is the largest number a greater than b should be true a greater than C also should be true if both are

true then only a is the largest number a greater than b returns true that means a Boolean value a greater than C also should returns true that is also Boolean value and if both are true then only we can say a is the largest number right so in that particular context which operator we have

to use between these two Boolean values both should be true then only the final value should be true so which operator we have to use between these two expressions end operator end is what logical operator okay so here a greater than b and a greater than C so this time we specified

two expressions remember this is one condition this is another condition both should be wrs true then only the final condition becomes true okay inside this we have written two expressions a greater than b and a greater than C both should returns true then only the if condition becomes

true okay even if one is false then if condition will become false so in both Expressions both both the Expressions it should both returns true so the if condition is true then what does it mean here we can simply say a is largest number a is the largest number so first validation is done

so this is done now suppose if this condition is false what does it mean if this condition is false what does it mean a is a not largest number right if a is the largest number OB viously this

if condition becomes true if this if condition is not becomes true what does it mean indirectly a is a not largest number so we need to compare next number what is the next one b b greater than a

and b greater than C then B is the largest number so how can we put another condition else if one more condition so here we can say a greater than b sorry B greater than a and B greater than C so

now we are comparing B with A and C so if both are true then this if condition becomes true so here we can say system B is a largest number B is a largest number so now the second condition

is also over now suppose even this condition is also Al return false so first condition checks a is largest or not second condition check B is largest or not if both the conditions are false what does it mean obviously C is the largest number is there any other case here nothing right

if both conditions are false then obviously C is the largest number so do you really want to put this condition not needed right so directly you can write in else block condition is not needed you can simply right system C is largest number so for comparison of C there is no condition not

required why because here we decided a is not largest number if it is false if the second condition is foral B is not largest obviously what is the other number we have is only C so we can say in lse blog we can simply say C is the largest number so this will execute only if about

two conditions are written false so about two conditions written false means what A and B are not largest numbers obviously the C is a largest number so this is how we can implement the logic and here if I notice we are using logical operators along with relational operator

the combinations because logical operators also will L true or false the if a condition required a Boolean value that expression whatever we have written is should return a Boolean value in the last class I think somebody asked where exactly we used the Boolean variables and Boolean values

so here all the conditional statements looping statements Works based upon the Boolean values okay so if this condition returns true true means what booing value if the condition return false false means what is also boing value okay based on the value the statements will be executed now let

us test this so first I'll say 10 20 30 so what we are expecting now C is the largest number so when I execute so you can say C is a largest number now let's make uh a is 100 now when execute you will

say a is the largest number now let's make B is 200 then it says b is a largest number okay so all all conditions are satisfied suppose instead of a b and c I just want to print a number also along

with this a BC I want to just print number also so that I can clearly know which number is largest number so how can we customize the statement so a is the largest number whatever you have put in

the double quotations it is as it is printing in the console window right now if you want to print the number also the same number I just want to print here simply what you can do concatenation let's plus a concatenation simple here also I want to print the Value Plus B concatenation so

here also you can simply say plus C concatenation right so when I execute it along with this it will also give the number right so guys understood how to specify multiple conditions multiple if conditions along with multiple uh Expressions so if condition can have one expression or if

condition can also have multiple Expressions if condition can have one expression or multiple Expressions okay so like this we can practice more number of examples by using uh if else conditions okay now let me show you one more example now this time you guys can tell the

output uh I'm just writing a simple program I can say multiple statements so as I said before in if Els condition we can also specify multiple statements right single statement or multiple statements let me show you one more example so here uh if true and here I'm printing one

else here I'm printing two first of all tell me this code is correct or not this code is correct or not valid code or not say yes or no everyone it is valid or not if true system P one else

two can we put a Boolean value Direct if condition without having any expression so I have not put any expression so just I'm specifying a boing value can we put like this why not we can easily put right ultimately we need a Boolean value here right even if you

say a greater than b or whatever what we are expecting from this a Boolean value right this will return return it true or false so instead of writing an expression I can directly write a boing value like this what's wrong in that right so if condition is always accepting a Boolean value

and that Boolean value can be a direct value or it can written by some expression okay so when I say if true then what is an output of this statement so this is true then if block will execute right so when I execute this see here you got one can we pass false here false

so if false then what will execute now if it is a false else block will execute so when I run this this will return true you got my point so what is my intention here is I just wanted to

tell you instead of writing an expression we can also Al write a a boan value because ultimately the expression will written true or false a boan value will be written by the expression right in all previous examples in if condition whatever expression we have written all those expressions

will return true or false a Bo value will be return returned okay so if it is a true then if block will execute if it is a false else block will execute I hope this is clear to everyone

got my point here we are not comparing anything actually here we are not comparing anything just we are WR some Boolean value because the ultimate goal of expression is when I compare something it will return true or false right instead of comparison I'm directly say some Boolean value

here it is valid because if condition always accepting either true or false boan value it can be directly or through expression whatever it is right you understood my context here in if condition you can pass an expression or you can pass a Boolean value directly that's what

I'm saying okay for example let's say here I'm saying 1 equal to 1 can we put like this 1 equal to 1 yes because this will also returns true or false 1 equal to one true or false true if

it is a true which one will execute if block will execute so it will print one okay when I say one equal to two the expression will return return false so else block will execute else block will execute so what I'm saying here is you can put either expression or you can directly put buan

value But ultimately the if condition required a Boolean value okay the if condition is always required provide a Boolean value if it is a true if block will execute if it is a false else block will execute okay that true or false you can directly specify with the Boolean value

or that comes through expression okay now let me show you some more examples now this time you guys can tell the output of this program okay so this is the one I'm commenting this at the time of practicing you can just uncomment and you can try okay this is second example

now you guys can tell me the output of this program so I can say if true okay and inside this I will put one more if condition okay so let me read the question first when in If part you passed the Boolean

value as a true okay then why it is passed first block and return Valu as one because if it is a true if it is a true obviously if block will execute right so if the condition is true if block will execute in if block what we have written here one only we have

written that is the reason it is printing one okay if a condition is true obviously the if block will execute that will return one if the condition is false then else block will execute then it will returns two because we put one and two in the print

statements okay yes now we can just see here if true again inside the if condition I'll put one more if condition this is called nested if else condition so the third one nested if Els condition the third approach nested if nested if Els means

what one if condition can have another if condition multiple nested if Els condition you can spfy so nested if Els I'm showing here so if it is a true and enter into the block here I will again say true and then here I'm printing some value so I can say

ABC ABC lse system print and XY J okay now after coming out of this if condition else here I will say 1 2 3 this is my code now tell me what is an output of this output ABC or XY Z or 1 2 3 which one what is an output of this code so this piece of

code okay so let us try to understand this so first we'll start from here the condition is true here if it is a true it will enter into the block so what is the block of this if statement from here to here this is all comes under if block first outer if block

okay and this is comes under first if block now if it is a true these statements should execute again if you come inside there is another if condition so if it is a true then ABC will execute else part will ignore okay so if it is true then ABC got executed so the output

of this code is what ABC so when I execute it will return ABC because the outer if condition is true it come inside and then it this is also true then the statement is called executed so rest of them will ignore okay suppose when I say false here now tell me what is an output

of this false so outer if condition is true so it is entered into this block but inner if condition is false if it is a false the else part immediate else block will execute that is XY Z so this is the output of this program XY Z okay now let us make this if condition

false now tell me the output of this so if condition is false means these statements will not be executed so this if block will ignore obviously come to else block inside this we put one 23 so it will execute obviously 1 2

3 okay so this is how we can also write multiple if conditions and nested if else conditions one if condition can have multiple if conditions one if condition can have a multiple if else conditions so depends upon our requ requirement we

can use these statements control statements okay so we have seen only if a statement if El a statement nested if nested if in the sense one if condition can have another if condition multiple times you can specify now let me show you one more example for multiple if

conditions so example five so in this now I want to just print weak names display weak names based on week number okay that means I will provide some number when I say one the program should display Sunday when I provide

two the program should display Monday so when I provide a number between 127 the corresponding week name should be displayed as an output okay so how many weeks we have totally seven weeks Sunday to Saturday right so all these seven weeks we have to print based upon the week number

so what is the input here week number is an input okay so we need to check multiple conditions if the week number is one then print Monday if the week number is two then print Tuesday if the week

number three then print another so like this we can write multiple conditions okay so let's try to do this close and new class and print weak names take this main method say finish so based upon the weak number I want to just print name of the veker so what is an input here what is

a variable you have to take a weak numers so I'll take integer variable in week number let us start with one first now we need to check this weak number we need to compare with uh multiple weak numbers like 1 2 3 4 5 up to seven so what is the first one if this weak number equal to one if the

weak number equal to one what we should say this is Sunday this is Sunday else one more condition else if week number equal to two then we can say m day one more condition else if the weak number

weak number equal to three then you can say to St so multiple conditions you can keep like this if Els if Els it FS like this so all the conditions we can verify like this because total seven weeks

are there so four five six and finally what seven obviously the last one uh is seven so that I can keep LF also lsf week number equal to 7 then I can print certainty okay suppose if I provide invalid

number other than 1 to 7 so weak number should be between 1 to 7 so if the week number is other than 1 to7 then what we should say invalid weak number we should display invalid weak number so

now what we need to do if we specify more number of conditions if none of them are not satisfied finally else Block in this we can say invalid week number because this else block will execute after completion of all the conditions if no condition is not matching finally else block will execute

so this is invalid weak number you can print like this so multiple conditions also we can verify by using IF else conditions like this okay now let us test this code so initially say week number one so execute say Sunday so that means the first condition itself is matched so thus this

statement is got executed and as soon as this condition is matched so rest of the conditions will not be verified okay now let us make this seven sorry here seven week number seven so it will verify all the conditions one by one and finally one condition is got matched here week

number seven so it is got printed Saturday fine now let's say 10 here 10 so when I said 10 no condition is matching so finally else block will execute so it will say number is invalid weak number okay so this is how we can Implement logic so we can also write multiple

conditions multiple if else conditions depends upon your requirement you can frame the logic okay so these are all conditional statements we have seen if condition if else condition nested if Els condition means if conditions can also have another if conditions and finally switch

case statement so when we have to use switch case this is also comes under conditional statement but we need to understand when we have to use switch case statement switch case statement uh we will prefer to use if we have a more number of conditions for example let's look at this example

here we have almost seven conditions so how many lines of code we have written here almost 40 plus almost 40 plus lines of code we have written to verify the seven conditions so if you have more conditions like this seven conditions sometimes you have a 10 condition 20 conditions if you have

a more conditions like this instead of using IF Els conditions better to go with a switch case statement why because switch case statement will reduce the lot of code in switch case statement it will also perform the same thing the objective of same whatever the IFL condition is doing here

same thing we can achieve by using switch case statement but what is a major advantage of it is it will reduce the code it will reduce the code so why we need to red uce the codee because if you

are saying a developer is writing very good code on what basis you will say if if the developer is more efficient he will write a small thing and do bigger task inefficient developers they will write a big code but do the small task so unnecessarily we should not increase the size

of the code we always try to reduce the code with minimal code we should achieve the larger things so then only he's a efficient developer so instead of writing more number of f conditions like this more much much code we can try to reduce this code by rating the switch case statement right so now

let me show you how can we write switch case statement and how to use switch case statement same program I will try to write a switch case using switch case and then we will see how much of lines it will almost 50% of the code will be reduced okay now we'll see the first syntax

syntax switch case so the syntax will be like this first we need to start with the switch and here we don't specify the condition Cas okay we specify the variable okay and inser this switch we will write one

thing called case keyword Case Case is a keyword here we specify the value of the variable okay so if the variable value is equal to this one let's say value one okay and then here we specify the statements okay and suppose if the variable value is not equal to this one then another

Case Case value equal to two then execute another set of statements and suppose even this variable is not equal to this value two then another Case Case value three and then execute statements and if the variable value is not equal to any of these value not matching

with any of these values then finally we specify default it is just like a else block so if none of the cases are not matching finally default block statements will execute this is a switch case switch and case syntax so now let me show you how can we use this uh with this switch case

commands so can we write a program without declaring the variable using conditional statement yes you can write if you have such requirement you can write you can directly put the expression because why variables are needed you need to first understand that concept why we

need to create a variable what is the importance of variable to store the data right to store the data or to maintain the data we have to create a variables if you do not have variables what you want to achieve with the program if you do not have any variables defined in your program

what you want to achieve first of all you need to clear about your goal right why you are writing the program what you want to achieve with this program if you're clear about the goal objective then you will know exactly variables are required or not okay variables are required or not so just

think logically guys why variables are required to store the data and you have some data now you want to have some comparison then what you will do definitely you will go with the control statements and if you don't want to compare anything then don't go with the conditional

statements if you have such requirement for example I just create created two variables I just want to print the values of them do you need control statements if else conditions you you need them you don't need just you create a variables and you're printing the data just by

using print statement you can print values of a b c you're not comparing anything so no need any control statements or if El conditions but if you want to compare something if you want to do some operation based upon certain conditions definitely you have to write a if else conditions

you guys understood so variables definitely we needed for almost in every program without variable we don't write any program first of all it doesn't make any sense without variable you don't want to achieve anything right if you want to achieve something we have to write

some program some logic some implementation should be there if you just want to print a name I don't need any control statement what is the main achievement for this right if you just simply write a system pintel and your name what is the main objective of the program if

your objective is just printing the data you don't need conditional statements but if you want to perform certain operations based upon certain conditions comparison all these things you need to use conditional statements so you can write program you can use conditional statement

with variables and without variables also but if I don't want to use variables there is no objective of that program see in the previous example in multiple statements here uh have you written any variables here did I create any variables here in this

program have you written any variables no right I haven't used any variables still I have used conditional statements why because I directly put the values instead of writing variables and storing the data I directly put the values here so I have not used variables it

depends on your requirement it keeps changing okay so the input also we can pass through the console window at the run time so that I will show in the coming sessions because we want to know the scanner class so through the scanner class we can take this input at the run time so

once your program is got executed at the run time you can provide the number randomly you can pass input that is possible okay that I will cover in the coming sessions for now just follow this approach okay okay so now let us see how can we write the same program using switch case

statement so if you want to achieve this we have written almost 40 lines of gold 40 plus lines of gold when I use if else conditions right but if you write the same program by using switch case statement we'll see how many lines of code is got reduced fine so let me create another class

switch case most important listen carefully many times we prefer to use this switch case statement okay just observe so I already told you syntax so if the switch variable here we should not specify any condition okay we just specify only variables and here we are comparing it so

first we'll take a variable ENT weak number let's take one now we need to write a switch case statement how to start switch and here we specify the variable what is the variable here weak number is a variable and inside this switch we have to write a multiple cases so what

is the first case here is case if the weak number equal to one here value is what one if the weak number is one colon here we have to put colon not curly Braes okay colon here you can write whatever the statement you want to execute so here I want to execute system. can say

something and after completion of the statement immediately you have to write one more thing called break break is basically called jumping statement but here we have to use break command after executing the statement but I'll tell you why we have to use this break statement

just hold on so this is one case suppose if the weak number is not matching with one then another Case Case two here system print say Monday again after the statement break bre okay like this I can write multiple conditions I can write multiple

conditions okay so you can put this break statement in the next line or in the same line no problem because the semicolon is representing the end of the line this statement is got ended so after that you can put the statement in the next line or you can keep in the same line no

problem like this okay now we can put multiple conditions case 1 2 3 4 up to seven conditions we have to specify so here we can write seven conditions like this and after completion of all seven cases finally if suppose none of the cases are not matching then finally default here

we have to say system P invalid weak number here break is not required here break is not required okay so this is our program see how much size it has got reduced almost 50% of the code is got reduced if I use switch Cas statement okay now let us first test this code and after that

we'll see how it is got executed so week number one means what week number one and case one is matching so obviously it will print Sunday okay Sunday is going printed now let's make it as a seven so seven me seventh case matched and Saturday got printed now let us

make [Music] 10 okay so 10 so let's try to execute copy Java application now invalid weak so default is got executed if none of the cases are not matching finally default is got executed fine it's perfectly working fine now let us try to understand how this

code is got executing and why we need this break additional statement in every case so normally switch case statements uh we work based upon the case not condition actually so this week number equal to one then this statement will execute if you not specified

the break here for example if you're not specified the break then what will happen Okay let me remove the break here okay and we'll see what will happen let's say make it as a one so first case is matching the statement will execute right so when I execute this just

observe what happens it is displayed two week numbers Sunday is fine because the case one is got matched Sunday is got printed now immediately what is printing Monday also it is printing so how it is happened because as soon as the statement is got printed immediately it will execute the

next statement without checking any case without checking this case by default the second statement will be executed okay so if you put this break then what will happen after the statement is got executed we no need to execute the rest of the statements it doesn't make any sense right at

a time only one statement we want to execute so when you specify break automatically this Brak command will jump out from this switch command this come out from entire block wherever The Brak is got executed that will break the condition it will break the block it will come out from

this block automatically same thing suppose if the case one is not matching then it will go to case two and case two Monday is got displayed immediately break it will come out from the Block if I don't specify break here then what happens if break is not created here then what

happens so it is got printed Sunday so let me just put two here then so it has got printed Monday and also it is printed Tuesday because we haven't put we haven't put break here so now you understand what is the importance of break here if I don't put break

command it will automatically execute the next command next statement without checking any case so that is the reason as soon as your case is got executed immediately we have to use break command this is mandator required for every case but why we haven't specified break for default here

we just specify only statement there is no break can anyone guess why we haven't specify break for default why yes because after execution of the statement there is no other statement to be executed right this is the last statement obviously it will automatically break after

execution of this default statement it will Anyway come out from the Block so break is not at all needed here but rest of the cases break is mandator required so if I compared this with our previous example same program same objective we have achieved in two different ways

by writing multiple if conditions by writing a switch case statement and if you look at the size of The Code by using ifls conditions almost we have written 40 plus lines and by using switch case statement we have just written 20 plus lines almost 50% % of the code is got reduced so

this is the main advantage of using switch case statement so whenever you have a more number of conditions to verify or compare try to use switch case statement instead of using IF else condition statement so nothing wrong in this you can use if else or switch case both are correct but which

one will be used more efficiently when you compare switch case statement will be preferred okay this is also another type of switch case statement so these are all four different type of conditional statements which we have discussed if if else and N if else switch case these are all called

conditional statement first category of control statements so what is the use of conditional statements if you want to execute set of statement or statements based upon certain condition we can go with conditional statements conditional statements based upon the condition we can

choose the particular block we want to execute or not that we can decide based on the condition then we can go with conditional statements and we also have something called looping statements looping means the same set of statement we will repeat multiple times reputation will be there

and we have a while loop for Loop do while loop multiple type of looping statements are there so in the next session we will discuss about looping statements and then jumping statements okay and I got one question here is there a shortcut on the keyboard what is the shortcut or copy duplicate uh

shortcut to copy or duplicate the code like you do you can just copy paste control C and control V so actually some of the statements I already written somewhere so I'm just copying from there okay so you have to write it or you can just copy paste control C and call control V that's it nothing

new okay so based on these topics I will give you some assignments today so you guys can try those assignments it based on total today's topic conditional statements assignments okay so the first assignment so we have seen how to find largest of three numbers

right so by using multiple if else conditions so you guys can try largest of two numbers very small the largest of three numbers we WR multiple condition but here the conditions will be reduced largest of two numbers and you can achieve this by using two different ways using IF else conditions

you can try also by using tary operator this is very famous inter question tary operator do you guys remember what is tary operator yesterday we have discussed it tary operator so by using tary operator also we can achieve this solution simple one single line we can achieve this you

can also write if else conditions but instead of writing if else conditions you can simply write one single statement ternary operator to find largest of two numbers try this okay yesterday we have already discussed about tary operator now the second example we have seen

how to find largest of three numbers so you guys can try smallest of three numbers okay smallest of three numbers again you have to use if Els conditions multiple condition ifs okay now the third example you have to print weak name name okay so you have to print weak number based on

weak name exactly opposite we have here we have seen we have taken weak number as an input and printed weak names right now what you have to do you have to take weak name as an input and then print a weak name number here exactly you have to do reverse okay so you have to take a

weak name here as an input and here you have to specify the weak number so how to replace this so simple just I'm giving some clue you guys can try so here we say in week number equal to 2 3 4

5 right but here you have to take a string variable string week name equal to you can specify Sunday Monday or whatever you want this is the input string we have to take input but how can we compare this in the switch case and if you want to write a switch case you can write

like this switch and here we name whatever the variable we Define and how to write a cases here case 1 2 3 4 no because this 1 2 3 4 is a values actually weak numbers so here the weak names you

have to write okay case because it is a string we have to keep inside the double putting case Sunday like this okay case a Sunday then system. and one and then break like this you have to write you understood now so completely opposite so here we Tak the week name and comparing with

the week name in every case we have to write a week name Sunday Monday Tuesday thday like this seven week names and you have to print week number exactly opposite of this right so just you try this because we are keeping the strings right because if it is a string we have to keep inside

the double quotations if it is a number we can directly put the number try this so this is one assignment it is okay so so print week number based on week name so here use switch case okay so you guys can try these three examples today and tomorrow

once you discussed looping statements then I will give you some more assignments right so we stop here for today's session and tomorrow we'll continue it