While loop in Java

 While loop in Java

1. Syntax and flow of the while loop

while(condition) {
// body of a loop
}

The condition can be any boolean expression. The body of the loop will be executed as long as the conditional expression is true. When the condition becomes false, control passes to the next line of code immediately following the loop. 

In a while loop, a condition is evaluated first, and if it returns true then the statements inside while loop execute. When the condition returns false, the control comes out of a loop and jumps to the next statement after a while loop.

Example while loop

Here is a while loop that counts down from 10, printing exactly ten lines of "tick":

public class WhileLoopExample {
    public static void main(String args[]) {
        int n = 10;
        while (n > 0) {
            System.out.println("tick " + n);
            n--;
        }
    }
}

Output:

tick 10
tick 9
tick 8
tick 7
tick 6
tick 5
tick 4
tick 3
tick 2
tick 1

2. The while Loop with No Body

The body of the while (or any other of Java’s loops) can be empty. This is because a null statement (one that consists only of a semicolon) is syntactically valid in Java. For example, consider the following program:

public class WhileLoopNoBody {
    public static void main(String args[]) {
        int i, j;
        i = 100;
        j = 200;
        // find midpoint between i and j
        while (++i < --j)
        ; // no body in this loop
        System.out.println("Midpoint is " + i);
    }
}

Output:

Midpoint is 150

3. Infinite while Loop

If you pass true in the while loop, it will be an infinite while loop.

Syntax:

while(true){  
//code to be executed  
} 

Example:

public class WhileExample {
    public static void main(String[] args) {
        while (true) {
            System.out.println("infinitive while loop");
        }
    }
}

Output:

infinitive while loop
infinitive while loop
infinitive while loop
infinitive while loop
infinitive while loop