Java While loop

While Loop

The java while loop is used when the number of iterations is not known but the terminating condition is known. Loop is executed until the given condition evaluates to false. while loop is also an entry-controlled loop as the condition is checked before entering the loop. The test condition is checked first and then the control goes inside the loop

the while loop is a control flow statement that repeatedly executes a block of code as long as a specified condition is true. Unlike the for loop, the while loop does not have an initialization step or an iteration step within the loop declaration itself. Instead, these actions are typically performed within the loop body.

Flowchart

The syntax of a while loop in Java is as follows:

while (condition) {
    // Body of the loop
    // Code to execute repeatedly
    // Iteration or update of loop control variables
}

• Condition: This part specifies the boolean expression that is evaluated before each iteration. If the condition evaluates to true, the loop continues; if it evaluates to false, the loop terminates.
• Body of the loop: This is the block of code that is executed repeatedly as long as the condition is true. It contains the statements that you want to execute in each iteration.

Here’s an example of a while loop in Java:

public class Main {

  public static void main(String args[]) {
    int factorial = 1, number = 5, tempNum = 0;
    tempNum = number; // Initialization;
    while (tempNum != 0) { // Test Expression
      factorial = factorial * tempNum;
      --tempNum; //Updation;
    }
    System.out.println("The factorial of " + number + " is: " + factorial);
  }
}

output

The factorial of 5 is: 120

Variations In While Loop

Multiple Condition Expression

In Java, you can use multiple condition expressions in a while loop to check multiple conditions simultaneously. By combining conditions using logical operators like “&&” (AND) or “||” (OR), you can create complex conditions that control the loop’s execution.

Example

int age = 25;
boolean isStudent = true;

while (age < 30 && isStudent) {
    // Loop body
    age++;
}

Empty While Loop

In Java, an empty while loop is a loop structure that does not have any statements or code inside its body. It consists of the while keyword followed by parentheses, which contain the loop’s condition.

Example:

while (condition) {
    // Empty loop body
}

Conclusion

The while loop in Java is a versatile control flow statement used for executing a block of statements repeatedly as long as a given condition remains true. It’s particularly useful in scenarios where the number of iterations is not predetermined. By allowing for multiple conditions and even having the capability to run without any body statements, while loops provide programmers with the flexibility to handle a wide range of repetitive tasks effectively.

Understanding how to properly use while loops, including variations like loops with multiple conditions and empty loops, is crucial for creating efficient and effective Java programs. These loops are fundamental in programming, enabling developers to implement solutions that require repetitive actions, such as iterating through data structures, performing calculations until a condition is met, or simply waiting for an event to occur.

Frequently Asked Questions