Module java.base
Package java.util

Class AbstractMap.SimpleEntry<K,V>

java.lang.Object
java.util.AbstractMap.SimpleEntry<K,V>
Type Parameters:
K - the type of key
V - the type of the value
All Implemented Interfaces:
Serializable, Map.Entry<K,V>
Enclosing class:
AbstractMap<K,V>
public static class AbstractMap.SimpleEntry<K,V> extends Object implements Map.Entry<K,V>, Serializable
An Entry maintaining a key and a value. The value may be changed using the setValue method. Instances of this class are not associated with any map nor with any map's entry-set view.
API Note:
This class facilitates the process of building custom map implementations. For example, it may be convenient to return arrays of SimpleEntry instances in method Map.entrySet().toArray.
Since:
1.6
See Also:

  • Constructor Summary

    Constructors
    Constructor
    Description
    SimpleEntry(Map.Entry<? extends K,? extends V> 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.

  • 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.
    String
    toString()
    Returns a String representation of this map entry.

    Methods declared in class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

  • Constructor Details

    • 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<? extends K,? extends V> entry)
      Creates an entry representing the same mapping as the specified entry.
      Parameters:
      entry - the entry to copy

  • Method Details

    • 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. 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

      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:

    • 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