2021-04-28 16:49:39 +02:00
It's almost always a mistake to compare two instances of ``++java.lang.String++`` or boxed types like ``++java.lang.Integer++`` using reference equality ``++==++`` or ``++!=++``, because it is not comparing actual value but locations in memory.
== Noncompliant Code Example
----
String firstName = getFirstName(); // String overrides equals
String lastName = getLastName();
if (firstName == lastName) { ... }; // Non-compliant; false even if the strings have the same value
----
== Compliant Solution
----
String firstName = getFirstName();
String lastName = getLastName();
if (firstName != null && firstName.equals(lastName)) { ... };
----
== See
* http://cwe.mitre.org/data/definitions/595.html[MITRE, CWE-595] - Comparison of Object References Instead of Object Contents
* http://cwe.mitre.org/data/definitions/597.html[MITRE, CWE-597] - Use of Wrong Operator in String Comparison
* https://wiki.sei.cmu.edu/confluence/x/UjdGBQ[CERT, EXP03-J.] - Do not use the equality operators when comparing values of boxed primitives
* https://wiki.sei.cmu.edu/confluence/x/yDdGBQ[CERT, EXP50-J.] - Do not confuse abstract object equality with reference equality
