Complete Java masterclass for beginners -09 (If-else statement)

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Java If-else Statement

The Java if statement is used to test the condition. It checks boolean condition: true or false. There are various types of if statement in Java.
  • if statement
  • if-else statement
  • if-else-if ladder
  • nested if statement

Java if Statement

The Java if statement tests the condition. It executes the if block if condition is true.

Syntax:

if(condition){
//code to be executed 
        }


Example:

//Java Program to demonstate the use of if statement.  

public class IfExample {

    public static void main(String[] args) {

        //defining an 'age' variable  

        int age=20;

        //checking the age  

        if(age>18){

            System.out.print("Age is greater than 18");

        }

    }

}

Output:

Java if-else Statement

The Java if-else statement also tests the condition. It executes the if block if condition is true otherwise else block is executed.
Syntax:
if(condition){

//code if condition is true  

        }else{

//code if condition is false  

        }


Example:

public class IfElseExample {

    public static void main(String[] args) {

        //defining a variable  

        int number=13;

        //Check if the number is divisible by 2 or not  

        if(number%2==0){

            System.out.println("even number");

        }else{

            System.out.println("odd number");

        }

    }

}

Output:


Leap Year Example:

A year is leap, if it is divisible by 4 and 400. But, not by 100.

public class LeapYearExample {

    public static void main(String[] args) {

        int year=2020;

        if(((year % 4 ==0) && (year % 100 !=0)) || (year % 400==0)){

            System.out.println("LEAP YEAR");

        }

        else{

            System.out.println("COMMON YEAR");

        }

    }

}

 Output:


Using Ternary Operator

We can also use ternary operator (? :) to perform the task of if...else statement. It is a shorthand way to check the condition. If the condition is true, the result of ? is returned. But, if the condition is false, the result of : is returned.
Example:
public class IfElseTernaryExample {

    public static void main(String[] args) {

        int number=13;

        //Using ternary operator  

        String output=(number%2==0)?"even number":"odd number";

        System.out.println(output);

    }

}

Output:

Java if-else-if ladder Statement

The if-else-if ladder statement executes one condition from multiple statements.
Syntax:
if(condition1){

//code to be executed if condition1 is true  

        }else if(condition2){

//code to be executed if condition2 is true  

        }

        else if(condition3){

//code to be executed if condition3 is true  

        }

        ...

        else{

//code to be executed if all the conditions are false  

        } 



public class IfElseIfExample {

    public static void main(String[] args) {

        int marks=65;



        if(marks<50){

            System.out.println("fail");

        }

        else if(marks>=50 && marks<60){

            System.out.println("D grade");

        }

        else if(marks>=60 && marks<70){

            System.out.println("C grade");

        }

        else if(marks>=70 && marks<80){

            System.out.println("B grade");

        }

        else if(marks>=80 && marks<90){

            System.out.println("A grade");

        }else if(marks>=90 && marks<100){

            System.out.println("A+ grade");

        }else{

            System.out.println("Invalid!");

        }

    }

}

Output:



Program to check POSITIVE, NEGATIVE or ZERO:

public class PositiveNegativeExample {

    public static void main(String[] args) {

        int number=-13;

        if(number>0){

            System.out.println("POSITIVE");

        }else if(number<0){

            System.out.println("NEGATIVE");

        }else{

            System.out.println("ZERO");

        }

    }

}

Output:

Java Nested if statement

The nested if statement represents the if block within another if block. Here, the inner if block condition executes only when outer if block condition is true.
Syntax:
if(condition){

        //code to be executed    

        if(condition){

        //code to be executed    

        }

        }

Example:

public class JavaNestedIfExample {

    public static void main(String[] args) {

        //Creating two variables for age and weight  

        int age=20;

        int weight=80;

        //applying condition on age and weight  

        if(age>=18){

            if(weight>50){

                System.out.println("You are eligible to donate blood");

            }

        }

    }}

Output:


Example 2:

public class JavaNestedIfExample2 {

    public static void main(String[] args) {

        //Creating two variables for age and weight    

        int age=25;

        int weight=48;

        //applying condition on age and weight    

        if(age>=18){

            if(weight>50){

                System.out.println("You are eligible to donate blood");

            } else{

                System.out.println("You are not eligible to donate blood");

            }

        } else{

            System.out.println("Age must be greater than 18");

        }

    }  } 

Output:


Next Topic
Java Switch Statement

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