The equality operator.
The default behavior for all Objects is to return true if and only if this
and other
are the same object.
Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:
Total: It must return a boolean for all arguments. It should never throw or return null
.
Reflexive: For all objects o
, o == o
must be true.
Symmetric: For all objects o1
and o2
, o1 == o2
and o2 == o1
must either both be true, or both be false.
Transitive: For all objects o1
, o2
, and o3
, if o1 == o2
and o2 == o3
are true, then o1 == o3
must be true.
The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.
If a subclass overrides the equality operator it should override the hashCode method as well to maintain consistency.
external bool operator ==(other);
© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dartlang.org/stable/2.0.0/dart-core/Object/operator_equals.html