com.google.api.client.util

Class ArrayMap<K,V>

  • Type Parameters:
    K - the type of keys maintained by this map
    V - the type of mapped values
    All Implemented Interfaces:
    Cloneable, Map<K,V> 

    public class ArrayMap<K,V>
extends AbstractMap<K,V>
implements Cloneable
    Memory-efficient map of keys to values with list-style random-access semantics.

    Supports null keys and values. Conceptually, the keys and values are stored in a simpler array in order to minimize memory use and provide for fast access to a key/value at a certain index (for example getKey(int)). However, traditional mapping operations like get(Object) and put(Object, Object) are slower because they need to look up all key/value pairs in the worst case.

    Implementation is not thread-safe. For a thread-safe choice instead use an implementation of ConcurrentMap.

    Since:
    1.0

    • Constructor Summary

      Constructors

      Constructor and Description
      ArrayMap()
       

    • Method Summary

      Modifier and Type Method and Description
      void add(K key, V value)
      Adds the key/value mapping at the end of the list.
      void clear()
       
      ArrayMap<K,V> clone()
       
      boolean containsKey(Object key)
      Returns whether there is a mapping for the given key.
      boolean containsValue(Object value)
       
      static <K,V> ArrayMap<K,V> create()
      Returns a new instance of an array map with initial capacity of zero.
      static <K,V> ArrayMap<K,V> create(int initialCapacity)
      Returns a new instance of an array map of the given initial capacity.
      void ensureCapacity(int minCapacity)
      Ensures that the capacity of the internal arrays is at least a given capacity.
      Set<Map.Entry<K,V>> entrySet()
       
      V get(Object key)
      Returns the value set for the given key or null if there is no such mapping or if the mapping value is null.
      int getIndexOfKey(K key)
      Returns the index of the given key or -1 if there is no such key.
      K getKey(int index)
      Returns the key at the given index or null if out of bounds.
      V getValue(int index)
      Returns the value at the given index or null if out of bounds.
      static <K,V> ArrayMap<K,V> of(Object... keyValuePairs)
      Returns a new instance of an array map of the given key value pairs in alternating order.
      V put(K key, V value)
      Sets the value for the given key, overriding any existing value.
      V remove(int index)
      Removes the key/value mapping at the given index, or ignored if the index is out of bounds.
      V remove(Object key)
      Removes the key-value pair of the given key, or ignore if the key cannot be found.
      V set(int index, K key, V value)
      Sets the key/value mapping at the given index, overriding any existing key/value mapping.
      V set(int index, V value)
      Sets the value at the given index, overriding any existing value mapping.
      int size()
      Returns the number of key-value pairs set.
      void trim()
      Trims the internal array storage to minimize memory usage.

    • Constructor Detail

      • ArrayMap

        public ArrayMap()

    • Method Detail

      • create

        public static <K,V> ArrayMap<K,V> create()
        Returns a new instance of an array map with initial capacity of zero. Equivalent to calling the default constructor, except without the need to specify the type parameters. For example: ArrayMap<String, String> map = ArrayMap.create();.

      • create

        public static <K,V> ArrayMap<K,V> create(int initialCapacity)
        Returns a new instance of an array map of the given initial capacity. For example: ArrayMap<String, String> map = ArrayMap.create(8);.

      • of

        public static <K,V> ArrayMap<K,V> of(Object... keyValuePairs)
        Returns a new instance of an array map of the given key value pairs in alternating order. For example: ArrayMap<String, String> map = ArrayMap.of("key1", "value1", "key2", "value2", ...);.

        WARNING: there is no compile-time checking of the keyValuePairs parameter to ensure that the keys or values have the correct type, so if the wrong type is passed in, any problems will occur at runtime. Also, there is no checking that the keys are unique, which the caller must ensure is true.

      • size

        public final int size()
        Returns the number of key-value pairs set.

      • getKey

        public final K getKey(int index)
        Returns the key at the given index or null if out of bounds.

      • getValue

        public final V getValue(int index)
        Returns the value at the given index or null if out of bounds.

      • set

        public final V set(int index,
                   K key,
                   V value)
        Sets the key/value mapping at the given index, overriding any existing key/value mapping.

        There is no checking done to ensure that the key does not already exist. Therefore, this method is dangerous to call unless the caller can be certain the key does not already exist in the map.

        Returns:
        previous value or null for none
        Throws:
        IndexOutOfBoundsException - if index is negative

      • set

        public final V set(int index,
                   V value)
        Sets the value at the given index, overriding any existing value mapping.
        Returns:
        previous value or null for none
        Throws:
        IndexOutOfBoundsException - if index is negative or >= size

      • add

        public final void add(K key,
                      V value)
        Adds the key/value mapping at the end of the list. Behaves identically to set(size(), key, value).
        Throws:
        IndexOutOfBoundsException - if index is negative

      • remove

        public final V remove(int index)
        Removes the key/value mapping at the given index, or ignored if the index is out of bounds.
        Returns:
        previous value or null for none

      • containsKey

        public final boolean containsKey(Object key)
        Returns whether there is a mapping for the given key.

      • getIndexOfKey

        public final int getIndexOfKey(K key)
        Returns the index of the given key or -1 if there is no such key.

      • get

        public final V get(Object key)
        Returns the value set for the given key or null if there is no such mapping or if the mapping value is null.

      • put

        public final V put(K key,
                   V value)
        Sets the value for the given key, overriding any existing value.
        Specified by:
        put in interface  Map<K,V>
        Overrides:
        put in class  AbstractMap<K,V>
        Returns:
        previous value or null for none

      • remove

        public final V remove(Object key)
        Removes the key-value pair of the given key, or ignore if the key cannot be found.
        Specified by:
        remove in interface  Map<K,V>
        Overrides:
        remove in class  AbstractMap<K,V>
        Returns:
        previous value or null for none

      • trim

        public final void trim()
        Trims the internal array storage to minimize memory usage.

      • ensureCapacity

        public final void ensureCapacity(int minCapacity)
        Ensures that the capacity of the internal arrays is at least a given capacity.

      • clear

        public void clear()

      • containsValue

        public final boolean containsValue(Object value)