Class IntHashMap<T>


  • public class IntHashMap<T>
    extends Object

    A hash map that uses primitive ints for the key rather than objects.

    Note that this class is for internal optimization purposes only, and may not be supported in future releases of Apache Commons Lang. Utilities of this sort may be included in future releases of Apache Commons Collections.

    Since:
    2.0
    See Also:
    HashMap
    • Constructor Summary

      Constructors 
      Constructor Description
      IntHashMap()
      Constructs a new, empty hashtable with a default capacity and load factor, which is 20 and 0.75 respectively.
      IntHashMap​(int initialCapacity)
      Constructs a new, empty hashtable with the specified initial capacity and default load factor, which is 0.75.
      IntHashMap​(int initialCapacity, float loadFactor)
      Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Clears this hashtable so that it contains no keys.
      boolean contains​(Object value)
      Tests if some key maps into the specified value in this hashtable.
      boolean containsKey​(int key)
      Tests if the specified object is a key in this hashtable.
      boolean containsValue​(Object value)
      Returns true if this HashMap maps one or more keys to this value.
      T get​(int key)
      Returns the value to which the specified key is mapped in this map.
      boolean isEmpty()
      Tests if this hashtable maps no keys to values.
      Object put​(int key, T value)
      Maps the specified key to the specified value in this hashtable.
      protected void rehash()
      Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently.
      Object remove​(int key)
      Removes the key (and its corresponding value) from this hashtable.
      int size()
      Returns the number of keys in this hashtable.
    • Constructor Detail

      • IntHashMap

        public IntHashMap()

        Constructs a new, empty hashtable with a default capacity and load factor, which is 20 and 0.75 respectively.

      • IntHashMap

        public IntHashMap​(int initialCapacity)

        Constructs a new, empty hashtable with the specified initial capacity and default load factor, which is 0.75.

        Parameters:
        initialCapacity - the initial capacity of the hashtable.
        Throws:
        IllegalArgumentException - if the initial capacity is less than zero.
      • IntHashMap

        public IntHashMap​(int initialCapacity,
                          float loadFactor)

        Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.

        Parameters:
        initialCapacity - the initial capacity of the hashtable.
        loadFactor - the load factor of the hashtable.
        Throws:
        IllegalArgumentException - if the initial capacity is less than zero, or if the load factor is non-positive.
    • Method Detail

      • size

        public int size()

        Returns the number of keys in this hashtable.

        Returns:
        the number of keys in this hashtable.
      • isEmpty

        public boolean isEmpty()

        Tests if this hashtable maps no keys to values.

        Returns:
        true if this hashtable maps no keys to values; false otherwise.
      • contains

        public boolean contains​(Object value)

        Tests if some key maps into the specified value in this hashtable. This operation is more expensive than the containsKey method.

        Note that this method is identical in functionality to containsValue, (which is part of the Map interface in the collections framework).

        Parameters:
        value - a value to search for.
        Returns:
        true if and only if some key maps to the value argument in this hashtable as determined by the equals method; false otherwise.
        Throws:
        NullPointerException - if the value is null.
        See Also:
        containsKey(int), containsValue(Object), Map
      • containsValue

        public boolean containsValue​(Object value)

        Returns true if this HashMap maps one or more keys to this value.

        Note that this method is identical in functionality to contains (which predates the Map interface).

        Parameters:
        value - value whose presence in this HashMap is to be tested.
        Returns:
        boolean true if the value is contained
        Since:
        JDK1.2
        See Also:
        Map
      • containsKey

        public boolean containsKey​(int key)

        Tests if the specified object is a key in this hashtable.

        Parameters:
        key - possible key.
        Returns:
        true if and only if the specified object is a key in this hashtable, as determined by the equals method; false otherwise.
        See Also:
        contains(Object)
      • get

        public T get​(int key)

        Returns the value to which the specified key is mapped in this map.

        Parameters:
        key - a key in the hashtable.
        Returns:
        the value to which the key is mapped in this hashtable; null if the key is not mapped to any value in this hashtable.
        See Also:
        put(int, Object)
      • rehash

        protected void rehash()

        Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently.

        This method is called automatically when the number of keys in the hashtable exceeds this hashtable's capacity and load factor.

      • put

        public Object put​(int key,
                          T value)

        Maps the specified key to the specified value in this hashtable. The key cannot be null.

        The value can be retrieved by calling the get method with a key that is equal to the original key.

        Parameters:
        key - the hashtable key.
        value - the value.
        Returns:
        the previous value of the specified key in this hashtable, or null if it did not have one.
        Throws:
        NullPointerException - if the key is null.
        See Also:
        get(int)
      • remove

        public Object remove​(int key)

        Removes the key (and its corresponding value) from this hashtable.

        This method does nothing if the key is not present in the hashtable.

        Parameters:
        key - the key that needs to be removed.
        Returns:
        the value to which the key had been mapped in this hashtable, or null if the key did not have a mapping.
      • clear

        public void clear()

        Clears this hashtable so that it contains no keys.