Empty Loop in Java

Rumman Ansari   Software Engineer   2025-11-06 07:55:26   180  Share
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🔹 Definition:

If a loop does not contain any statement in its loop-body, it is called an empty loop.
In such cases, Java implicitly includes a null statement (;) as the loop body.

That means the loop executes but performs no operation during each iteration.

🧩 Syntax:


for (initialization; condition; update);

The semicolon (;) after the loop header represents a null statement (empty body).


✅ Example 1: Simple Empty Loop


public class EmptyLoopExample {
    public static void main(String[] args) {
        int j;

        // Empty for loop
        for (j = 20; j >= 0; j--);

        System.out.println("Loop completed, final value of j = " + j);
    }
}

🧠 Explanation:

  • The loop body is empty (only a semicolon ;).

  • The variable j starts from 20 and keeps decreasing until it becomes -1.

  • The loop does not perform any action inside — it just updates the variable.

💬 Output:


Loop completed, final value of j = -1


🕒 Example 2: Empty Loop as a Time Delay Loop

Empty loops are sometimes used to create a delay, especially in embedded systems or simple console programs (though not recommended in real applications today).


public class TimeDelayExample {
    public static void main(String[] args) {
        int t;

        System.out.println("Please wait...");

        // Empty loop to create time delay
        for (t = 0; t < 300000000; t++);  // Loop does nothing

        System.out.println("Done!");
    }
}


⚙️ Explanation:

  • This loop runs 300 million times doing nothing — just consuming CPU time.

  • It introduces a time delay before printing "Done!".

  • In real programs, Thread.sleep(milliseconds) is preferred instead of using empty loops for delays.


📘 In short:

Feature Description
Loop body Contains only a null statement (;)
Purpose To repeat variable updates without performing actions
Common use Time delay loops or waiting for a condition change



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