Class ArrayMap<K,V>

java.lang.Object
java.util.AbstractMap<K,V>
com.google.api.client.util.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

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    (package private) final class 
    ArrayMap.Entry
     
    (package private) final class 
    ArrayMap.EntryIterator
     
    (package private) final class 
    ArrayMap.EntrySet
     

    Nested classes/interfaces inherited from class AbstractMap

    AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private Object[]
    data
     
    (package private) int
    size
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    ArrayMap()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    final void
    add(K key, V value)
    Adds the key/value mapping at the end of the list.
    void
    clear()
     
    ArrayMap<K,V>
    clone()
     
    final boolean
    containsKey(Object key)
    Returns whether there is a mapping for the given key.
    final 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.
    final void
    ensureCapacity(int minCapacity)
    Ensures that the capacity of the internal arrays is at least a given capacity.
    final Set<Map.Entry<K,V>>
    entrySet()
     
    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.
    private int
    getDataIndexOfKey(Object key)
    Returns the data index of the given key or -2 if there is no such key.
    final int
    getIndexOfKey(K key)
    Returns the index of the given key or -1 if there is no such key.
    final K
    getKey(int index)
    Returns the key at the given index or null if out of bounds.
    final 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.
    final V
    put(K key, V value)
    Sets the value for the given key, overriding any existing value.
    final V
    remove(int index)
    Removes the key/value mapping at the given index, or ignored if the index is out of bounds.
    final V
    remove(Object key)
    Removes the key-value pair of the given key, or ignore if the key cannot be found.
    private V
    removeFromDataIndexOfKey(int dataIndexOfKey)
    Removes the key/value mapping at the given data index of key, or ignored if the index is out of bounds.
    final V
    set(int index, K key, V value)
    Sets the key/value mapping at the given index, overriding any existing key/value mapping.
    final V
    set(int index, V value)
    Sets the value at the given index, overriding any existing value mapping.
    private void
    setData(int dataIndexOfKey, K key, V value)
     
    private void
    setDataCapacity(int newDataCapacity)
     
    final int
    size()
    Returns the number of key-value pairs set.
    final void
    trim()
    Trims the internal array storage to minimize memory usage.
    private V
    valueAtDataIndex(int dataIndex)
     

    Methods inherited from class AbstractMap

    equals, hashCode, isEmpty, keySet, putAll, toString, values

    Methods inherited from class Object

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

    Methods inherited from interface Map

    compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

  • Field Details

    • size

      int size

    • data

      private Object[] data

  • Constructor Details

    • ArrayMap

      public ArrayMap()

  • Method Details

    • 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.
      Specified by:
      size in interface Map<K,V>
      Overrides:
      size in class AbstractMap<K,V>

    • 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.
      Specified by:
      containsKey in interface Map<K,V>
      Overrides:
      containsKey in class AbstractMap<K,V>

    • 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.
      Specified by:
      get in interface Map<K,V>
      Overrides:
      get in class AbstractMap<K,V>

    • 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.

    • setDataCapacity

      private void setDataCapacity(int newDataCapacity)

    • setData

      private void setData(int dataIndexOfKey, K key, V value)

    • valueAtDataIndex

      private V valueAtDataIndex(int dataIndex)

    • getDataIndexOfKey

      private int getDataIndexOfKey(Object key)
      Returns the data index of the given key or -2 if there is no such key.

    • removeFromDataIndexOfKey

      private V removeFromDataIndexOfKey(int dataIndexOfKey)
      Removes the key/value mapping at the given data index of key, or ignored if the index is out of bounds.

    • clear

      public void clear()
      Specified by:
      clear in interface Map<K,V>
      Overrides:
      clear in class AbstractMap<K,V>

    • containsValue

      public final boolean containsValue(Object value)
      Specified by:
      containsValue in interface Map<K,V>
      Overrides:
      containsValue in class AbstractMap<K,V>

    • entrySet

      public final Set<Map.Entry<K,V>> entrySet()
      Specified by:
      entrySet in interface Map<K,V>
      Specified by:
      entrySet in class AbstractMap<K,V>

    • clone

      public ArrayMap<K,V> clone()
      Overrides:
      clone in class AbstractMap<K,V>