ArrayBag Class

import java.util.Arrays; import java.util.ArrayList; public class ArrayBag<T> implements BagInterface<T> { /** * The bag which holds all the items added to it. * * @var array * @access private **/ private T[] bag; /** * The default capacity. This value is a constant, it cannot be * altered. To change the value of DEFAULT_CAPACITY, simply instantiate * this object by passing an integer parameter to it. * * @var final integer * @access private **/ private int DEFAULT_CAPACITY; /** * The number of entries contain in the bag. * * @var integer * @access private **/ private int numberOfEntries = 0; /** * Constructor method. This method initialize DEFAULT_CAPACITY to 10. * When the capacity is full, we'll never add a new item to it. * **/ public ArrayBag(){ DEFAULT_CAPACITY = 10; bag = init(); } /** * Another constructor method that accepts a parameter. We'll then set the * value to it. * * @param c */ public ArrayBag(int c){ DEFAULT_CAPACITY = c; bag = init(); } public final T[] init(){ return (T[]) new Object[DEFAULT_CAPACITY]; } @Override public int getCurrentSize(){ return numberOfEntries; } @Override public boolean isFull() { int capacity = DEFAULT_CAPACITY; return (getCurrentSize() >= capacity || getCurrentSize() == capacity); } @Override public boolean isEmpty() { return ( getCurrentSize() <= 0 ); } @Override public boolean add(T newEntry) { if ( isFull() || newEntry == null ) return false; bag[ numberOfEntries ] = newEntry; numberOfEntries++; return true; } @Override public boolean add_distinct(T newEntry){ if ( isFull() || newEntry == null || this.contains(newEntry) ) return false; bag[ numberOfEntries ] = newEntry; numberOfEntries++; return true; } @Override public boolean add(T... newEntries){ T[] original_bag = bag; boolean flag = false; for ( T entry : newEntries ){ flag = add(entry); // one of the entry cannot be added, reverse to the original bag. if ( ! flag ){ bag = original_bag; return flag; } } return flag; } @Override public T remove() { int n = numberOfEntries; T target = bag[n-1]; T[] new_bag = init(); System.arraycopy(bag, 0, new_bag, 0, numberOfEntries-1); if ( new_bag.length >= 0 ){ bag = new_bag; numberOfEntries--; } return numberOfEntries < n ? target : null; } @Override public boolean remove(T anEntry) { if ( !contains(anEntry) ) return false; T[] new_bag = init(); int j = 0; for ( int i=0; i<getCurrentSize(); i++ ){ if ( ! anEntry.equals(bag[i]) ){ new_bag[j] = bag[i]; j++; } } if ( new_bag.length >= 0 ){ bag = new_bag; numberOfEntries--; } return true; } @Override public void clear() { bag = init(); numberOfEntries = 0; } @Override public int getFrequencyOf(T anEntry) { int fq = 0; for ( T x : bag ) if ( anEntry.equals(x) ) fq++; return fq; } @Override public boolean contains(T anEntry) { for ( int i = 0; i<numberOfEntries; i++ ) if ( anEntry.equals(bag[i]) ) return true; return false; } @Override public T[] toArray() { T[] return_bag = init(); for ( int i=0, j=0; i < getCurrentSize(); i++, j++ ) if ( get(i) != null ) return_bag[j] = bag[i]; else break; return return_bag; } @Override public BagInterface<T> union(BagInterface<T> object){ BagInterface<T> bags = new ArrayBag(DEFAULT_CAPACITY + object.toArray().length); bags.add(bag); bags.add(object.toArray()); return bags; } @Override public BagInterface<T> intersect(BagInterface<T> object){ T[] bag1 = bag, bag2 = object.toArray(); int size = DEFAULT_CAPACITY + bag1.length; BagInterface<T> bags = new ArrayBag(DEFAULT_CAPACITY + bag1.length); ArrayList<T> c1 = new ArrayList<T>( Arrays.asList(bag1) ); ArrayList<T> c2 = new ArrayList<T>( Arrays.asList(bag2) ); c1.retainAll(c2); for ( int i=0; i < c1.size(); i++ ) bags.add( c1.get(i) ); return bags; } @Override public BagInterface<T> difference(BagInterface<T> object){ T[] bag1 = bag, bag2 = object.toArray(); BagInterface<T> bags = new ArrayBag(DEFAULT_CAPACITY + object.getCurrentSize()); for ( int i=0; i<getCurrentSize(); i++ ) for ( int j=0; j<object.getCurrentSize(); j++ ){ if ( ! bag1[i].equals(bag2[j]) ){ bags.add(bag1[i]); break; } } return bags; } @Override public T get(int index){ return bag[index]; } }