Package icyllis.modernui.util

Class SparseBooleanArray

java.lang.Object
icyllis.modernui.util.SparseBooleanArray
All Implemented Interfaces:
Cloneable
public class SparseBooleanArray extends Object implements Cloneable
SparseBooleanArrays map integers to booleans. Unlike a normal array of booleans there can be gaps in the indices. It is intended to be more memory efficient than using a HashMap to map Integers to Booleans, both because it avoids auto-boxing keys and values and its data structure doesn't rely on an extra entry object for each mapping.

Note that this container keeps its mappings in an array data structure, using a binary search to find keys. The implementation is not intended to be appropriate for data structures that may contain large numbers of items. It is generally slower than a traditional HashMap, since lookups require a binary search and adds and removes require inserting and deleting entries in the array. For containers holding up to hundreds of items, the performance difference is not significant, less than 50%.

It is possible to iterate over the items in this container using keyAt(int) and valueAt(int). Iterating over the keys using keyAt(int) with ascending values of the index will return the keys in ascending order, or the values corresponding to the keys in ascending order in the case of valueAt(int).

  • Constructor Summary

    Constructors
    Constructor
    Description
    SparseBooleanArray()
    Creates a new SparseBooleanArray containing no mappings.
    SparseBooleanArray(int initialCapacity)
    Creates a new SparseBooleanArray containing no mappings that will not require any additional memory allocation to store the specified number of mappings.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    append(int key, boolean value)
    Puts a key/value pair into the array, optimizing for the case where the key is greater than all existing keys in the array.
    void
    clear()
    Removes all key-value mappings from this SparseBooleanArray.
    SparseBooleanArray
    clone()
     
    void
    delete(int key)
    Removes the mapping from the specified key, if there was any.
    boolean
    equals(Object that)
     
    boolean
    get(int key)
    Gets the boolean mapped from the specified key, or false if no such mapping has been made.
    boolean
    get(int key, boolean defaultValue)
    Gets the boolean mapped from the specified key, or the specified value if no such mapping has been made.
    int
    hashCode()
     
    int
    indexOfKey(int key)
    Returns the index for which keyAt(int) would return the specified key, or a negative number if the specified key is not mapped.
    int
    indexOfValue(boolean value)
    Returns an index for which valueAt(int) would return the specified key, or a negative number if no keys map to the specified value.
    int
    keyAt(int index)
    Given an index in the range 0...size()-1, returns the key from the indexth key-value mapping that this SparseBooleanArray stores.
    void
    put(int key, boolean value)
    Adds a mapping from the specified key to the specified value, replacing the previous mapping from the specified key if there was one.
    void
    removeAt(int index)
    Removes the mapping at the specified index.
    void
    setKeyAt(int index, int key)
     
    void
    setValueAt(int index, boolean value)
    Directly set the value at a particular index.
    int
    size()
    Returns the number of key-value mappings that this SparseBooleanArray currently stores.
    String
    toString()
    boolean
    valueAt(int index)
    Given an index in the range 0...size()-1, returns the value from the indexth key-value mapping that this SparseBooleanArray stores.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • SparseBooleanArray

      public SparseBooleanArray()
      Creates a new SparseBooleanArray containing no mappings.

    • SparseBooleanArray

      public SparseBooleanArray(int initialCapacity)
      Creates a new SparseBooleanArray containing no mappings that will not require any additional memory allocation to store the specified number of mappings. If you supply an initial capacity of 0, the sparse array will be initialized with a light-weight representation not requiring any additional array allocations.

  • Method Details

    • get

      public boolean get(int key)
      Gets the boolean mapped from the specified key, or false if no such mapping has been made.

    • get

      public boolean get(int key, boolean defaultValue)
      Gets the boolean mapped from the specified key, or the specified value if no such mapping has been made.

    • delete

      public void delete(int key)
      Removes the mapping from the specified key, if there was any.

    • removeAt

      public void removeAt(int index)
      Removes the mapping at the specified index.

    • put

      public void put(int key, boolean value)
      Adds a mapping from the specified key to the specified value, replacing the previous mapping from the specified key if there was one.

    • size

      public int size()
      Returns the number of key-value mappings that this SparseBooleanArray currently stores.

    • keyAt

      public int keyAt(int index)
      Given an index in the range 0...size()-1, returns the key from the indexth key-value mapping that this SparseBooleanArray stores.

      The keys corresponding to indices in ascending order are guaranteed to be in ascending order, e.g., keyAt(0) will return the smallest key and keyAt(size()-1) will return the largest key.

    • valueAt

      public boolean valueAt(int index)
      Given an index in the range 0...size()-1, returns the value from the indexth key-value mapping that this SparseBooleanArray stores.

      The values corresponding to indices in ascending order are guaranteed to be associated with keys in ascending order, e.g., valueAt(0) will return the value associated with the smallest key and valueAt(size()-1) will return the value associated with the largest key.

    • setValueAt

      public void setValueAt(int index, boolean value)
      Directly set the value at a particular index.

    • setKeyAt

      public void setKeyAt(int index, int key)

    • indexOfKey

      public int indexOfKey(int key)
      Returns the index for which keyAt(int) would return the specified key, or a negative number if the specified key is not mapped.

    • indexOfValue

      public int indexOfValue(boolean value)
      Returns an index for which valueAt(int) would return the specified key, or a negative number if no keys map to the specified value. Beware that this is a linear search, unlike lookups by key, and that multiple keys can map to the same value and this will find only one of them.

    • clear

      public void clear()
      Removes all key-value mappings from this SparseBooleanArray.

    • append

      public void append(int key, boolean value)
      Puts a key/value pair into the array, optimizing for the case where the key is greater than all existing keys in the array.

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(@Nullable Object that)
      Overrides:
      equals in class Object

    • toString

      public String toString()

      This implementation composes a string by iterating over its mappings.

      Overrides:
      toString in class Object

    • clone

      public SparseBooleanArray clone()
      Overrides:
      clone in class Object