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@ekumachidi
Last active October 8, 2015 08:22
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import java.util.Iterator;
import java.util.NoSuchElementException;
public class ResizingArrayBag<Item> implements Iterable<Item> {
private Item[] a; // array of items
private int N = 0; // number of elements on stack
public ResizingArrayBag() {//initialize an empty array
a = (Item[]) new Object[2];
}
/*Is this bag empty?*/
public boolean isEmpty() {
return N == 0;
}
/*Size*/
public int size() {
return N;
}
// resize the underlying array holding the elements
private void resize(int capacity) {
assert capacity >= N;
Item[] temp = (Item[]) new Object[capacity];
for (int i = 0; i < N; i++)
temp[i] = a[i];
a = temp;
}
/* Adds the item to this bag.
* @param item the item to add to this bag
*/
public void add(Item item) {
if (N == a.length) resize(2*a.length); // double size of array if necessary
a[N++] = item; // add item
}
/**
* Returns an iterator that iterates over the items in the bag in arbitrary order.
* @return an iterator that iterates over the items in the bag in arbitrary order
*/
public Iterator<Item> iterator() {
return new ArrayIterator();
}
// an iterator, doesn't implement remove() since it's optional
private class ArrayIterator implements Iterator<Item> {
private int i = 0;
public boolean hasNext() { return i < N; }
public void remove() { throw new UnsupportedOperationException(); }
public Item next() {
if (!hasNext()) throw new NoSuchElementException();
return a[i++];
}
}
/**
* Unit tests the <tt>ResizingArrayBag</tt> data type.
*/
public static void main(String[] args) {
ResizingArrayBag<String> bag = new ResizingArrayBag<String>();
bag.add("Hello");
bag.add("World");
bag.add("how");
bag.add("are");
bag.add("you");
for (String s : bag)
StdOut.println(s);
}
}
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