Module java.base
Package java.util

Class AbstractMap.SimpleEntry<K,​V>

  • All Implemented Interfaces:
    Serializable,Map.Entry<K,​V>
    Enclosing class:
    AbstractMap<K,​V>
    public static classAbstractMap.SimpleEntry<K,​V>extendsObjectimplementsMap.Entry<K,​V>,Serializable
    An Entry maintaining a key and a value. The value may be changed using thesetValue method. This class facilitates the process of building custom map implementations. For example, it may be convenient to return arrays ofSimpleEntry instances in methodMap.entrySet().toArray.
    Since:
    1.6
    See Also:
    Serialized Form

    • Constructor Summary

      Constructors 
      ConstructorDescription
      SimpleEntry​(Map.Entry<? extendsK,​? extendsV> entry)
      Creates an entry representing the same mapping as the specified entry.
      SimpleEntry​(K key,V value)
      Creates an entry representing a mapping from the specified key to the specified value.

    • Constructor Detail

      • SimpleEntry

        public SimpleEntry​(K key,V value)
        Creates an entry representing a mapping from the specified key to the specified value.
        Parameters:
        key - the key represented by this entry
        value - the value represented by this entry

      • SimpleEntry

        public SimpleEntry​(Map.Entry<? extendsK,​? extendsV> entry)
        Creates an entry representing the same mapping as the specified entry.
        Parameters:
        entry - the entry to copy

    • Method Detail

      • getKey

        public K getKey()
        Returns the key corresponding to this entry.
        Specified by:
        getKey in interface Map.Entry<K,​V>
        Returns:
        the key corresponding to this entry

      • getValue

        public V getValue()
        Returns the value corresponding to this entry.
        Specified by:
        getValue in interface Map.Entry<K,​V>
        Returns:
        the value corresponding to this entry

      • setValue

        public V setValue​(V value)
        Replaces the value corresponding to this entry with the specified value.
        Specified by:
        setValue in interface Map.Entry<K,​V>
        Parameters:
        value - new value to be stored in this entry
        Returns:
        the old value corresponding to the entry

      • equals

        public boolean equals​(Object o)
        Compares the specified object with this entry for equality. Returnstrue if the given object is also a map entry and the two entries represent the same mapping. More formally, two entriese1 ande2 represent the same mapping if
           (e1.getKey()==null ?    e2.getKey()==null :    e1.getKey().equals(e2.getKey()))   &&   (e1.getValue()==null ?    e2.getValue()==null :    e1.getValue().equals(e2.getValue()))
        This ensures that theequals method works properly across different implementations of theMap.Entry interface.
        Specified by:
        equals in interface Map.Entry<K,​V>
        Overrides:
        equals in class Object
        Parameters:
        o - object to be compared for equality with this map entry
        Returns:
        true if the specified object is equal to this map entry
        See Also:
        hashCode()

      • hashCode

        public int hashCode()
        Returns the hash code value for this map entry. The hash code of a map entrye is defined to be:
           (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^   (e.getValue()==null ? 0 : e.getValue().hashCode())
        This ensures thate1.equals(e2) implies thate1.hashCode()==e2.hashCode() for any two Entriese1 ande2, as required by the general contract ofObject.hashCode().
        Specified by:
        hashCode in interface Map.Entry<K,​V>
        Overrides:
        hashCode in class Object
        Returns:
        the hash code value for this map entry
        See Also:
        equals(java.lang.Object)

      • toString

        public String toString()
        Returns a String representation of this map entry. This implementation returns the string representation of this entry's key followed by the equals character ("=") followed by the string representation of this entry's value.
        Overrides:
        toString in class Object
        Returns:
        a String representation of this map entry