CodeQL documentation

Dereferenced expression may be null

ID: java/dereferenced-expr-may-be-null
Kind: problem
Severity: warning
Precision: high
   - reliability
   - correctness
   - exceptions
   - external/cwe/cwe-476
Query suites:
   - java-security-and-quality.qls

Click to see the query in the CodeQL repository

Dereferencing a null value leads to a NullPointerException.

An expression may be implicitly dereferenced if its type is a boxed primitive type, and it occurs in a context in which implicit unboxing occurs.


Ensure that the expression does not have a null value when it is dereferenced. Use boxed types as appropriate to hold values that are potentially null.


In the following example implicit unboxing can cause a NullPointerException if helper is null.

public int getID() {
    return helper == null ? null : helper.getID();

If the method is intended to return null, the return type should be changed to Integer.