Useless null check¶
ID: java/useless-null-check
Kind: problem
Security severity:
Severity: warning
Precision: very-high
Tags:
- maintainability
- useless-code
- external/cwe/cwe-561
Query suites:
- java-security-and-quality.qls
Click to see the query in the CodeQL repository
Sometimes you can guarantee that a particular variable will never be null. For example when that variable has just been assigned a newly created object or is the exception caught by a catch clause. A null check on such a variable is misleading, and can potentially indicate a logic error.
Recommendation¶
Do not check a variable for null if a null value is clearly impossible.
Example¶
The following example shows a null check on a newly created object. An object returned by new can never be null, so this check is superfluous.
Object o = new Object();
if (o == null) {
// this cannot happen!
}
References¶
Java Language Specification: Creation of New Class Instances, Execution of try-catch.
Common Weakness Enumeration: CWE-561.