Module java.base
Package java.util

Class AbstractMap.SimpleImmutableEntry<K,​V>

  • All Implemented Interfaces:
    Serializable, Map.Entry<K,​V>
    Enclosing class:
    AbstractMap<K,​V>
    public static class AbstractMap.SimpleImmutableEntry<K,​V>
extends Object
implements Map.Entry<K,​V>, Serializable
    An Entry maintaining an immutable key and value. This class does not support method setValue. This class may be convenient in methods that return thread-safe snapshots of key-value mappings.
    Since:
    1.6
    See Also:
    Serialized Form

    • Constructor Summary

      Constructors 
      Constructor Description
      SimpleImmutableEntry​(Map.Entry<? extends K,​? extends V> entry)
      Creates an entry representing the same mapping as the specified entry.
      SimpleImmutableEntry​(K key, V value)
      Creates an entry representing a mapping from the specified key to the specified value.

    • Method Summary

      Modifier and Type Method Description
      boolean equals​(Object o)
      Compares the specified object with this entry for equality.
      K getKey()
      Returns the key corresponding to this entry.
      V getValue()
      Returns the value corresponding to this entry.
      int hashCode()
      Returns the hash code value for this map entry.
      V setValue​(V value)
      Replaces the value corresponding to this entry with the specified value (optional operation).
      String toString()
      Returns a String representation of this map entry.

    • Constructor Detail

      • SimpleImmutableEntry

        public SimpleImmutableEntry​(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

      • SimpleImmutableEntry

        public SimpleImmutableEntry​(Map.Entry<? extends K,​? extends V> 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 (optional operation). This implementation simply throws UnsupportedOperationException, as this class implements an immutable map entry.
        Specified by:
        setValue in interface Map.Entry<K,​V>
        Parameters:
        value - new value to be stored in this entry
        Returns:
        (Does not return)
        Throws:
        UnsupportedOperationException - always

      • equals

        public boolean equals​(Object o)
        Compares the specified object with this entry for equality. Returns true if the given object is also a map entry and the two entries represent the same mapping. More formally, two entries e1 and e2 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 the equals method works properly across different implementations of the Map.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 entry e is defined to be: 
           (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
   (e.getValue()==null ? 0 : e.getValue().hashCode())
        This ensures that e1.equals(e2) implies that e1.hashCode()==e2.hashCode() for any two Entries e1 and e2, as required by the general contract of Object.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