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If the value
pbeing boxed istrue,false, abyte, acharin the range\u0000to\u007f, or anintorshortnumber between-128and127, then letr1andr2be the results of any two boxing conversions ofp. It is always the case thatr1 == r2.
Primitive Type | Boxed Type | Fully Memoized |
|---|---|---|
|
| Yes |
|
| No |
Use of the == and != operators for comparing the values of fully memoized boxed primitive types is permitted.
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Using the equivalence operators to compare values of boxed primitives can lead to erroneous comparisons.
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
EXP03-J | Low | Likely | Medium | P6 | L2 |
Automated Detection
Detection of all uses of the reference equality operators on boxed primitive objects is straightforward. Determining the correctness of such uses is infeasible in the general case.
Tool | Version | Checker | Description |
|---|---|---|---|
| Coverity | 7.5 | BAD_EQ | Implemented |
| Parasoft Jtest |
|
|
| PB.CUB.UEIC |
| SonarQube |
|
|
| S1698 |
| "==" and "!=" should not be used when "equals" is overridden |
Related Guidelines
CWE-595, Comparison of Object References Instead of Object Contents |
Bibliography
Puzzle 4, "Searching for the One" | |
[JLS 2015] | |
Using == to Compare Objects Rather than | |
| [Seacord 2015] |
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