Loops in Java

Looping

In Programming, looping is used to repeat the block of the code. E.g., if you want to print your name 100 times, you can use a loop. It will save your time and reduce duplicate code.

Types Of Loop

For Loop
While Loop
Do While Loop

For Loop

This is the most common type of loop. You can use for loop to run a block of code multiple times according to condition.

Syntax

for(initialization; condition; increment/decrement){
 statements;
}

Initialization is executed (one time) before the execution of the code block.
Condition defines the condition for executing the code block.
Increment/decrement is executed (every time) after the code block has been executed.

Example to print 1 to 10 using for loop.


public class Main {
    public static void main(String[] args) {
    for(int i=1; i<=10; i++){
    System.out.println(i);
    }
      
    }
}

Show Output

Example to print your name ten times.

public class Main {
    public static void main(String[] args) {
        for(int i=1; i<=10; i++){
    System.out.println("John Doe");
    }
    }
}

Show Output

Example to print 10 to 1 using for loop.

public class Main {
    public static void main(String[] args) {
        for(int i=10; i>=1; i--){
    System.out.println(i);
    }
    }
}

Show Output

While Loop

While loop is used to run a block of code while a certain condition is true. You must write conditions first before statements.

Syntax

while(condition){
     statements;
}

Example to print 1 to 10 using while loop

public class Main {
    public static void main(String[] args) {
        int i =1;
        while(i<=10){
        System.out.println(i);
        i++;
        }
        }
    }

Show Output

Example to print 10 to 1 using while loop

public class Main {
    public static void main(String[] args) {
        int i =1;
        while(i<=10){
        System.out.println(i);
        i++;
        }
    }
}

Show Output

Do While Loop

Do while loop is used to run a block of code multiple times. In do-while loop, you execute statements first and check conditions last.

Info

Note: If the condition is false do-while loop executes statements at least one time.

Syntax

do{
   statements;
}while(condition);

Example to print 1 to 10 using do-while loop

public class Main {
    public static void main(String[] args) {
         int i =1;
         do{
            System.out.println(i);
            i++;
         }while(i<=10);
    }
}

Show Output

Example to print 10 to 1 using do while loop

public class Main {
    public static void main(String[] args) {
         int i =10;
         do{
             System.out.println(i);
             i--;
        }while(i>=1);
    }
}

Show Output