equals()
, hashCode()
, compareTo()
, and
Comparator.compare()
methods.
Besides constructor invocations, new objects can also be created by autoboxing or iterator creation inside a
foreach
statement.
This can cause performance problems, for example, when objects are added to a Set
or Map
,
where these methods will be called often.
The inspection will not report when the objects are created in a throw
or assert
statement.
Example:
class Person {
private String name;
private int age;
public boolean equals(Object o) {
return Arrays.equals(new Object[] {name, age}, new Object[] {((Foo)o).name, ((Foo)o).age});
}
public int hashCode() {
return (name + age).hashCode();
}
}
In this example, two additional arrays are created inside equals()
, usages of age
field require boxing,
and name + age
implicitly creates a new string.