Package com.yahoo.collections

Class Hashlet<K,V>

java.lang.Object
com.yahoo.collections.Hashlet<K,V>
public final class Hashlet<K,V> extends Object
Lightweight hash map from key to value with limited functionality. This class lets you build a map from key to value. The value for a key may be overwritten and the put and get methods have the same semantics as for normal Java Maps, but there is no remove operation. Also, there is no iterator support, but keys and values can be accessed directly by index. The access order of keys and values are defined by the insert order of the keys. The goal of this class is to reduce the amount of object that are allocated by packing everything into two internal arrays. The keys and values are packed in an Object array and the hash table and entries are packed in an int array. The internal arrays are not created until space is needed. The default initial capacity is 16 entries. If you know you need much more space than this, you can explicitly reserve more space before starting to insert values. The maximum load factor is 0.7 and drops slightly with increasing capacity.
Author:
Havard Pettersen

  • Constructor Summary

    Constructors
    Constructor
    Description
    Hashlet()
    Create an empty Hashlet.
    Hashlet(Hashlet<K,V> hashlet)
    Create a Hashlet that is a shallow copy of another Hashlet.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    equals(Object o)
     
    V
    get(Object key)
    Obtain the value for a specific key.
    int
    getIndexOfKey(Object key)
    Finds the index where the key,value pair is stored.
    int
    hashCode()
     
    K
    key(int i)
    Obtain a key.
    V
    put(K key, V value)
    Associate a value with a specific key.
    void
    reserve(int n)
    Reserve space for more key value pairs.
    V
    setValue(int i, V value)
    This will replace the value at the index give.
    int
    size()
    The current size.
    V
    value(int i)
    Obtain a value.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Hashlet

      public Hashlet()
      Create an empty Hashlet.

    • Hashlet

      public Hashlet(Hashlet<K,V> hashlet)
      Create a Hashlet that is a shallow copy of another Hashlet.
      Parameters:
      hashlet - the Hashlet to copy.

  • Method Details

    • reserve

      public void reserve(int n)
      Reserve space for more key value pairs. This method is used by the put method to perform rehashing when needed. It can be invoked directly by the application to reduce the number of rehashes needed to insert a large number of entries.
      Parameters:
      n - the number of additional entries to reserve space for

    • size

      public int size()
      The current size. This is the number of key value pairs currently stored in this object.
      Returns:
      current size

    • key

      public K key(int i)
      Obtain a key. Keys are accessed in the order they were first inserted.
      Parameters:
      i - the index of the key, must be in the range [0, size() - 1]
      Returns:
      the requested key

    • value

      public V value(int i)
      Obtain a value. Values are accessed in the order in which theirs keys were first inserted.
      Parameters:
      i - the index of the value, must be in the range [0, size() - 1]
      Returns:
      the requested value

    • setValue

      public V setValue(int i, V value)
      This will replace the value at the index give.
      Parameters:
      i - the index of the value, must be in the range [0, size() - 1]
      value - The new value you want to set for this index.
      Returns:
      previous value

    • put

      public V put(K key, V value)
      Associate a value with a specific key.
      Parameters:
      key - the key
      value - the value
      Returns:
      the old value for the key, if it was already present

    • get

      public V get(Object key)
      Obtain the value for a specific key.
      Parameters:
      key - the key
      Returns:
      the value for a key, or null if not found

    • getIndexOfKey

      public int getIndexOfKey(Object key)
      Finds the index where the key,value pair is stored.
      Parameters:
      key - to look for
      Returns:
      the index where the key is found or -1 if it is not found

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object