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

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

snippet

//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

Age is greater than 18

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 #1

snippet

//A Java Program to demonstrate the use of if-else statement.
//It is a program of odd and even number.
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

odd number

Example #2

Leap Year Example:

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

snippet

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

LEAP YEAR

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

snippet

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

odd number

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
}

Example #1

snippet

//Java Program to demonstrate the use of If else-if ladder.
//It is a program of grading system for fail, D grade, C grade, B grade, A grade and A+.
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

C grade

Example #2

Program to check POSITIVE, NEGATIVE or ZERO:

snippet

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

NEGATIVE

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

snippet

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

Example #1

snippet

//Java Program to demonstrate the use of Nested If Statement.
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

You are eligible to donate blood

Example #2

snippet

//Java Program to demonstrate the use of Nested If Statement.  
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

You are not eligible to donate blood