equals()
, compareTo()
or similar, that compare an object for equality
with itself.
The method contracts of these methods specify that such calls will always return
true
for equals()
or 0
for compareTo()
.
The inspection also checks
calls to Objects.equals()
, Objects.deepEquals()
,
Arrays.equals()
, Comparator.compare()
, assertEquals()
methods of
test frameworks (JUnit, TestNG, AssertJ), Integer.compare()
, Integer.compareUnsigned()
and similar methods.
Note that in rare cases, the inspection may report equals()
calls that return false, because while the expressions
on the both sides are the same, they produce separate objects, and comparison is performed on references, rather than on content.
The simplest example is new Object().equals(new Object())
. In any case, such calls are suspicious, and likely
something else was intended.
Example:
class Foo {
boolean foo(Object o) {
return o.equals(o); // warning
}
boolean bar(String[] ss) {
return Arrays.equals(ss, ss); // warning
}
}