Empty Loop Body

ID

java.empty_loop_body

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

Java

Tags

CWE:1071, reliability

Description

Reports for, while, and do-while loops whose body is empty (either a bare semicolon or an empty block).

Rationale

An empty loop body is almost always a bug. A stray semicolon after the loop header turns the intended body into a separate statement that runs exactly once, outside the loop. Even when an empty loop is intentional (e.g., a busy-wait spin loop), the intent should be made explicit with a comment inside the braces.

// Bad -- stray semicolon makes the loop body empty
for (int i = 0; i < 10; i++);
    process(i);  // This runs once, not 10 times!

// Bad -- empty block
while (queue.poll() != null) {
}

Remediation

Move the intended statement inside the loop body:

// Good
for (int i = 0; i < 10; i++) {
    process(i);
}

References