Dereferenced variable may be null¶
ID: java/dereferenced-value-may-be-null
Kind: problem
Security severity:
Severity: warning
Precision: high
Tags:
- reliability
- correctness
- exceptions
- external/cwe/cwe-476
- non-local
Query suites:
- java-security-and-quality.qls
Click to see the query in the CodeQL repository
If a variable is dereferenced, and the variable may have a null value on some execution paths leading to the dereferencing, the dereferencing may result in a NullPointerException.
A variable may also be implicitly dereferenced if its type is a boxed primitive type, and the variable occurs in a context in which implicit unboxing occurs. Note that the conditional operator unboxes its second and third operands when one of them is a primitive type and the other is the corresponding boxed type.
Recommendation¶
Ensure that the variable does not have a null value when it is dereferenced.
Example¶
In the following example, the use of the conditional operator causes implicit unboxing, since the integer literal has type int. If the parameter p is ever null then a NullPointerException will occur.
public Integer f(Integer p) {
return true ? p : 5;
}
If the implicit unboxing is unintentional, it can be prevented by making sure that both branches of the conditional operator have the same type.
References¶
The Java Tutorials: Autoboxing and Unboxing.
Java Language Specification: Conditional Operator ? :.
Common Weakness Enumeration: CWE-476.