DynamicArray.java

package prove;

import java.util.Iterator;
import java.util.NoSuchElementException;

import edu.princeton.cs.introcs.In;
import edu.princeton.cs.introcs.StdOut;

public class DynamicArray<Item> implements Iterable<Item>, IterableCollection<Item> {
    Item[] A;
    int N; // Size of the array each moment. Different from capacity.

    @SuppressWarnings("unchecked")
    DynamicArray() {
        A = (Item[]) new Object[0];
        N = 0;
    }

    public void add(Item s) { // adds to the back

        if (A.length == 0)
            resize(1);

        if (N == A.length) {
            resize(2*A.length);
            StdOut.println("Resized for " + s);
        }
        A[N++] = s;
    }

    public void push_back(Item s) {
        add(s);
    }

    public Item get(int index) throws IndexOutOfBoundsException {
        if (index < 0 || index > N)
            throw new IndexOutOfBoundsException("Index out of bounds!");
        return A[index];
    }

    public void set(int index, Item value) throws IndexOutOfBoundsException {
        if (index < 0 || index > N)
            throw new IndexOutOfBoundsException("Index out of bounds!");
        A[index] = value;
    }

    public int capacity() {
        return A.length;
    }

    public int size() {
        return N;
    }

    public boolean isEmpty() {
        return N == 0;
    }

    public Item pop() {
        Item s = A[--N];
        A[N] = null; // Avoids loitering
        if (N > 0 && N == A.length / 4)
            resize(A.length / 2);
        return s;
    }

    private void resize(int capacity) {
            @SuppressWarnings("unchecked")
            Item[] newArray = (Item[]) new Object[capacity];
            for (int i=0; i < N; ++i) {
                newArray[i] = A[i];
            }
            A = newArray;
    }

    @Override
    public Iterator<Item> iterator() {
        return new DynamicArrayIterator();
    }

    private class DynamicArrayIterator implements Iterator<Item> {
        private int index;

        @Override
        public boolean hasNext() {
            if (index < size() - 1 ) return true;
            return false;
        }

        @Override
        public Item next() {
            if (!hasNext() ) throw new NoSuchElementException();
            return A[++index];

        }

        @Override
        public void remove() {
            throw new UnsupportedOperationException();
        }

    }

    public static void main(String args[]) throws Exception {
        In in = new In("input.txt");
        DynamicArray<String> v = new DynamicArray<String>();
        while (!in.isEmpty()) {
            String s = in.readString();
            v.push_back(s);
        }
        for (String str : v)
            StdOut.print(str);
    }



}