do-while loop in Java with Example

In Java or any other programming language, loops play an important role in executing a set of instructions multiple times based on a given condition. Inside a loop block, the set of instructions is fixed, and it executes repeatedly while some condition evaluates to true.

For example, if we have to print the same message 100 times, rather than typing the same code 100 times, we can use a loop here.

In this tutorial we are going to discuss do-while loop with definition, diagram and example.

The Java do-while loop is used to iterate a set of instructions repeatedly until the specified condition is true, but the do-while loop is a bit different from other loops because it executes first, then checks the specified condition, which means whether the condition is true or false, it executes at least once.

  do {    
    // loop body  
    // update statement   
  } while (condition);

Flowchart of Java do-while Loop

Example 1 : Java do-while Loop Program

  // Java Program to demonstrate the example of do-while loop 
  public class DoWhileLoopExample {
    public static void main(String[] args) {
      // Printing single message 5 times using do-while loop
      int i = 1;
      do {
        System.out.println("javabytechie.com");
        i++;
      } while (i <= 5);
    }
  }

Output

javabytechie.com
javabytechie.com
javabytechie.com
javabytechie.com
javabytechie.com

Java Nested do-while Loop:

Java also allows to write one do-while loop inside another do-while loop, it is knowns as Nested do-while loop or Inner do-while loop in Java.

Syntax of Nested do-while loop in Java

    // Outer do-while loop
    do {
      // outer loop body
      
      // Inner do-while loop
      do {
        // inner loop body
      } while(condition checking);
    } while(condition checking);

Now, let's understand Nested do-while loop through the given example.

Example 2 : Java Nested do-while Loop

  public class NestedDoWhileLoopExample {
    public static void main(String[] args) {
      int i = 1;
      // Outer do-while loop
      do {
        System.out.println("Outer do-while loop");
        i++;
        int j = 1;
        // Inner do-while loop
        do {
          System.out.println("Inner do-while loop");
          j++;
        } while (j <= 4);
      } while (i <= 3);
    }
  }

Output

Outer do-while loop
Inner do-while loop
Inner do-while loop
Inner do-while loop
Inner do-while loop
Outer do-while loop
Inner do-while loop
Inner do-while loop
Inner do-while loop
Inner do-while loop
Outer do-while loop
Inner do-while loop
Inner do-while loop
Inner do-while loop
Inner do-while loop

Infinite do-while Loop in Java

A loop that does not terminate that loop is known as an Infinite loop in Java.

Example 3 : Infinite do-while Loop in Java

  public class InfiniteDoWhileLoopExample {
    public static void main(String args[]) {
      do {
        System.out.println("It's an Infinite Loop");
      } while (true);
    }
  }

Output

It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
...
...
...

Continue and Break statements inside the do-while loop

We can use continue and break statements inside the do-while loop according to our requirements.

In Java, the continue statement is mainly used inside loops such as for loops, while loops, do-while loops, etc. The purpose of the continue statement is to continue the current running flow of the Java program and skip the rest of the code at the specified condition.

A break statement is used to terminate the current processing of the loop. After the termination, control returns from the loop immediately to the next statement after the loop.

Let's understand the below Java program where we are iterating a loop from 1 to 30 but printing the even value from 11-20.

Example 4 : Continue and Break Statements inside do-while Loop

  public class ContinueAndBreakInDoWhileLoop {
    public static void main(String[] args) {
      int i = 1;
      do {
        // Continue statement
        if (i < 11) {
          i++;
          continue;
        }
  
        // Printing even number
        if (i % 2 == 0)
          System.out.println("Even Number: " + i);
  
        // Break Statement
        if (i > 20)
          break;
        i++;
      } while (i <= 30);
    }
  }

Output

Even Number: 12
Even Number: 14
Even Number: 16
Even Number: 18
Even Number: 20

do-while Loop in Java with Example

Java Nested do-while Loop:

Infinite do-while Loop in Java

Continue and Break statements inside the do-while loop

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