Java Tutorial: While Loops in Java

• In programming languages, loops are used to execute a particular statement/set of instructions again and again.
• The execution of the loop starts when some conditions become true.
• For example, print 1 to 1000, print multiplication table of 7, etc.
• Loops make it easy for us to tell the computer that a given set of instructions need to be executed repeatedly.

Types of Loops :

• Primarily, there are three types of loops in Java:
• While loop
• do-while loop
• for loop
• Let's look into these, one by one.

While loops :

• The while loop in Java is used when we need to execute a block of code again and again based on a given boolean condition.
• Use a while loop if the exact number of iterations is not known.
• If the condition never becomes false, the while loop keeps getting executed. Such a loop is known as an infinite loop.

/*
while (Boolean condition)

{

            // Statements    -> This keeps executing as long as the condition is true.

}
*/

• Example

int i=10;  
while(i>0){  
System.out.println(i);  
i--;  
}  

Flow control of while loop :

Quick Quiz: Write a program to print natural numbers from 100 to 200.

Code as described in the video :

public class cwh_21_ch5_loops {
    public static void main(String[] args) {
        System.out.println(1);
        System.out.println(2);
        System.out.println(3);

        System.out.println("Using Loops:");
        int i = 100;
        while(i<=200){
            System.out.println(i);
            i++;
        }
        System.out.println("Finish Running While Loop!");

//        while(true){
//            System.out.println("I am an infinite while loop!");
//        }
    }
}

• This is all for this tutorial, and we will discuss the do-while loop in the next tutorial.

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