Call it an unordered list or a multiset, this collection is defined by oxymorons : Set « Collections Data Structure « Java






  1. Java
  2. Collections Data Structure
  3. Set

Call it an unordered list or a multiset, this collection is defined by oxymorons

        
 
//package com.ryanm.util;

import java.util.NoSuchElementException;

/**
 * Call it an unordered list or a multiset, this collection is defined by
 * oxymorons. Find the original <a href=http://riven8192.blogspot.com/
 * 2009/08/bag-unordered-list-fast-remove.html>over here</a>
 * 
 * @author Riven
 * @param <T>
 */
public class Bag<T> {
  private T[] data;

  private int size;

  /***/
  public Bag() {
    this(4);
  }

  /**
   * @param space
   *            initial size of bag
   */
  @SuppressWarnings("unchecked")
  public Bag(int space) {
    this.data = (T[]) new Object[space];
  }

  /**
   * Add an element
   * 
   * @param t
   */
  public void put(T t) {
    data = ensure(data, size + 1, 1.75f);
    data[size++] = t;
  }

  /**
   * Adds a lot of elements
   * 
   * @param bag
   */
  public void putAll(Bag<T> bag) {
    if (bag.size == 0) {
      return;
    }

    data = ensure(data, this.size + bag.size, 1.75f);
    System.arraycopy(bag.data, 0, this.data, this.size, bag.size);
    this.size += bag.size;
  }

  /**
   * Retrieves an element
   * 
   * @param index
   * @return the indexed element
   */
  public T get(int index) {
    if (index >= size) {
      throw new ArrayIndexOutOfBoundsException();
    }
    return data[index];
  }

  /**
   * Retrieves and removes an element
   * 
   * @param index
   * @return The indexed element
   */
  public T take(int index) {
    if (index >= size) {
      throw new ArrayIndexOutOfBoundsException();
    }

    T took = data[index];
    data[index] = data[--size];
    data[size] = null;
    return took;
  }

  /**
   * Attempts to remove an element
   * 
   * @param t
   *            The element to remove
   * @return t
   * @throws NoSuchElementException
   *             if the element was not found
   */
  public T take(T t) {
    int i = this.indexOf(t);
    if (i == -1) {
      throw new NoSuchElementException();
    }
    return this.take(i);
  }

  /**
   * Tests if an element is present
   * 
   * @param t
   * @return <code>true</code> if t is present, <code>false</code> otherwise
   */
  public boolean contains(T t) {
    return this.indexOf(t) != -1;
  }

  /**
   * Finds the index of an element
   * 
   * @param t
   * @return the index of t, or -1 if not found
   */
  public int indexOf(T t) {
    for (int i = 0; i < size; i++) {
      if (data[i] == t) {
        return i;
      }
    }
    return -1;
  }

  /**
   * Tries to shrink the internal array. If your {@link Bag} holds a lot of
   * elements temporarily and you're concerned with memory usage, it might be
   * worthwhile to call this after a sequence of {@link #take(int)} calls
   */
  @SuppressWarnings("unchecked")
  public void shrink() {
    if (this.data.length > 8) {
      int factor = 4;

      if (this.size < this.data.length / factor) {
        int newSize = Math.max(4, this.size);
        T[] newData = (T[]) new Object[newSize];
        System.arraycopy(this.data, 0, newData, 0, this.size);
        this.data = newData;
      }
    }
  }

  /**
   * Removes all elements
   */
  public void clear() {
    for (int i = 0; i < size; i++) {
      data[i] = null;
    }
    this.size = 0;
  }

  /**
   * The maximum number of elements allowed before the internal array will be
   * grown
   * 
   * @return The size of the internal array
   */
  public int capacity() {
    return this.data.length;
  }

  /**
   * @return The number of held elements
   */
  public int size() {
    return size;
  }

  @SuppressWarnings("unchecked")
  private static final <T> T[] ensure(T[] src, int minCapacity, float factor) {
    if (src.length >= minCapacity) {
      return src;
    }
    int newCapacity = src.length + 1;
    do {
      newCapacity *= factor;
    } while (newCapacity < minCapacity);

    T[] dst = (T[]) new Object[newCapacity];
    System.arraycopy(src, 0, dst, 0, src.length);
    return dst;
  }
}








Related examples in the same category

1.Set, HashSet and TreeSet
2.Things you can do with SetsThings you can do with Sets
3.Set operations: union, intersection, difference, symmetric difference, is subset, is superset
4.Set implementation that use == instead of equals()
5.Set that compares object by identity rather than equality
6.Set union and intersection
7.Set with values iterated in insertion order.
8.Putting your own type in a SetPutting your own type in a Set
9.Use setUse set
10.Another Set demo
11.Set subtractionSet subtraction
12.Working with HashSet and TreeSetWorking with HashSet and TreeSet
13.TreeSet DemoTreeSet Demo
14.Show the union and intersection of two sets
15.Demonstrate the Set interface
16.Array Set extends AbstractSetArray Set extends AbstractSet
17.Sync Test
18.Set Copy
19.Set and TreeSet
20.Tail
21.What you can do with a TreeSetWhat you can do with a TreeSet
22.Remove all elements from a set
23.Copy all the elements from set2 to set1 (set1 += set2), set1 becomes the union of set1 and set2
24.Remove all the elements in set1 from set2 (set1 -= set2), set1 becomes the asymmetric difference of set1 and set2
25.Get the intersection of set1 and set2, set1 becomes the intersection of set1 and set2
26.Extend AbstractSet to Create Simple Set
27.Int Set
28.One Item Set
29.Small sets whose elements are known to be unique by construction
30.List Set implements Set
31.Converts a char array to a Set
32.Converts a string to a Set
33.Implements the Set interface, backed by a ConcurrentHashMap instance
34.An IdentitySet that uses reference-equality instead of object-equality
35.An implementation of the java.util.Stack based on an ArrayList instead of a Vector, so it is not synchronized to protect against multi-threaded access.
36.A thin wrapper around a List transforming it into a modifiable Set.
37.A thread-safe Set that manages canonical objects
38.This program uses a set to print all unique words in System.in
39.Indexed Set
40.An ObjectToSet provides a java.util.Map from arbitrary objects to objects of class java.util.Set.
41.Sorted Multi Set
42.Fixed Size Sorted Set
43.Set operations
44.A NumberedSet is a generic container of Objects where each element is identified by an integer id.
45.Set which counts the number of times a values are added to it.
46.Set which counts the number of times a values are added to it and assigns them a unique positive index.
47.Indexed Set
48.A set acts like array.
49.Implements a Bloom filter. Which, as you may not know, is a space-efficient structure for storing a set.
50.Implementation of disjoint-set data structure