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package ch03;

import java.lang.Iterable;

import java.util.Iterator;

import java.util.NoSuchElementException;

/**

* Created by cookfront on 2017/2/20.

*/

public class MyArrayList<AnyType> implements Iterable<AnyType> {

private static final int DEFAULT_CAPACITY = 10;

private int theSize;

private AnyType[] theItems;

public MyArrayList() {

doClear();

}

public void clean() {

doClear();

}

private void doClear() {

theSize = 0;

ensureCapacity(DEFAULT_CAPACITY);

}

public int size() {

return theSize;

}

public boolean isEmpty() {

return size() == 0;

}

public void trimToSize() {

ensureCapacity(size());

}

public AnyType get(int index) {

if (index < 0 || index >= size()) {

throw new ArrayIndexOutOfBoundsException();

}

return theItems[index];

}

public AnyType set(int index, AnyType newVal) {

if (index < 0 || index >= size()) {

throw new ArrayIndexOutOfBoundsException();

}

AnyType old = theItems[index];

theItems[index] = newVal;

return old;

}

public void ensureCapacity(int newCapacity) {

if (newCapacity < theSize) {

return;

}

AnyType[] old = theItems;

theItems = (AnyType []) new Object[newCapacity];

for (int i = 0; i < size(); i++) {

theItems[i] = old[i];

}

}

public boolean add(AnyType val) {

add(size(), val);

return true;

}

public void add(int index, AnyType val) {

if (theItems.length == size()) {

ensureCapacity(size() * 2 + 1);

}

for (int i = theSize; i > index; i--) {

theItems[i] = theItems[i - 1];

}

theItems[index] = val;

theSize++;

}

public AnyType remove(int index) {

AnyType removedItem = theItems[index];

for (int i = index; i < size() - 1; i++) {

theItems[i] = theItems[i + 1];

}

return removedItem;

}

public Iterator<AnyType> iterator() {

return new ArrayListIterator();

}

private class ArrayListIterator implements Iterator<AnyType> {

private int current = 0;

public boolean hasNext() {

return current < size();

}

public AnyType next() {

if (!hasNext()) {

throw new NoSuchElementException();

}

return theItems[current++];

}

public void remove() {

MyArrayList.this.remove(--current);

}

}

}