javadictionarycollectionskey-value

Java - How to create new Entry (key, value)


I'd like to create new item that similarly to Util.Map.Entry that will contain the structure key, value.

The problem is that I can't instantiate a Map.Entry because it's an interface.

Does anyone know how to create a new generic key/value object for Map.Entry?


Solution

  • You can just implement the Map.Entry<K, V> interface yourself:

    import java.util.Map;
    
    final class MyEntry<K, V> implements Map.Entry<K, V> {
        private final K key;
        private V value;
    
        public MyEntry(K key, V value) {
            this.key = key;
            this.value = value;
        }
    
        @Override
        public K getKey() {
            return key;
        }
    
        @Override
        public V getValue() {
            return value;
        }
    
        @Override
        public V setValue(V value) {
            V old = this.value;
            this.value = value;
            return old;
        }
    }
    

    And then use it:

    Map.Entry<String, Object> entry = new MyEntry<String, Object>("Hello", 123);
    System.out.println(entry.getKey());
    System.out.println(entry.getValue());