Map.Entry interface enables you to work with a map entry.
The entrySet() method declared by the Map interface returns a Set containing the map entries.
Each of these set elements is a Map.Entry object.
Map.Entry is generic and is declared like this:
interface Map.Entry<K, V>
Here, K specifies the type of keys, and V specifies the type of values.
The following table summarizes the non-static methods declared by Map.Entry.
| Method | Description |
|---|---|
| boolean | equals(Object obj) Returns true if obj is a *Map. Entry* whose key and value are equal to that of the invoking object. |
| K | getKey() Returns the key for this map entry. |
| V | getValue() Returns the value for this map entry. |
| int | hashCode() Returns the hash code for this map entry. |
| V | setValue(V v) Sets the value for this map entry to v. A ClassCastException is thrown if v is not the correct type for the map. An IllegalArgumentException is thrown if there is a problem with v. |
JDK 8 adds two static methods.
The first is comparingByKey(), which returns a Comparator that compares entries by key.
The second is comparingByValue(), which returns a Comparator that compares entries by value.
A NullPointerException is thrown if v is null and the map does not permit null keys.
An UnsupportedOperationException is thrown if the map cannot be changed.
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