EqualsAvoidNull.md

Pattern: Possibly unsafe equals() comparison

Issue: -

Description

Checks that any combination of String literals is on the left side of an equals() comparison. Also checks for String literals assigned to some field (such as someString.equals(anotherString = "text")).

Rationale: Calling the equals() method on String literals will avoid a potential NullPointerException. Also, it is pretty common to see null checks right before equals comparisons, which is not necessary in the example below.

For example, this code:

String nullString = null;
nullString.equals("My_Sweet_String");

should be refactored to:

String nullString = null;
"My_Sweet_String".equals(nullString);

Examples

To configure the check:

<module name="EqualsAvoidNull"/>

Further Reading

• checkstyle - EqualsAvoidNull