Inexperienced Java developers might expect the Object.equals(Object obj) method to correctly handle the case where the left hand side is null, but that is not the case.

Noncompliant Code Example

if (variable.equals(null)) { /* ... */ }   // Noncompliant - "variable" is really null, a NullPointerException is thrown

Compliant Solution

if (variable == null) { /* ... */ }        // Compliant