Methods Named 'is…​' Should Return Boolean

ID

java.naming_is_boolean_return

Severity

low

Remediation Complexity

trivial

Remediation Risk

medium

Remediation Effort

low

Resource

Naming Convention

Language

Java

Tags

naming

Description

Reports methods whose names start with is that do not return boolean. The is prefix is a well-established convention for boolean queries.

Rationale

When a developer reads isReady(), they expect a yes/no answer. Returning int, String, or another non-boolean type violates this expectation, causing confusion and subtle bugs at call sites.

// Bad — name implies boolean but returns int
public int isOK() {
    return _value;
}

// Good — rename to reflect actual return type
public int getValue() {
    return _value;
}

Remediation

Either change the return type to boolean, or rename the method to drop the is prefix and use a name that reflects the actual return type (e.g., getXxx).

References