What methods, if any, does a custom class need to implement in order to be used as a key in a Map?
What methods, if any, does a custom class need to implement in order to
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What methods, if any, does a custom class need to implement in order to be used as a key in a Map?
This depends on the kind of your map:
HashMapmust providehashCodeandequalsTreeMapneed to providecompareToby implementingComparable<T>unless the map is constructed with aComparator, in which case there are no restrictions on the key itself.