package com.coding.basic.week01;
import java.util.Arrays;
public class ArrayList implements List {
private int size = 0;
private Object[] elementData = new Object[100];
public void add(Object o){
ensureCapacity(size + 1);
elementData[size++] = o;
}
public void ensureCapacity(int size) {
if (size > elementData.length) {
grow();
}
}
public void grow() {
elementData = Arrays.copyOf(elementData, size * 2);
}
public void add(int index, Object o){
if (index < 0 || index >= size) {
throw new ArrayIndexOutOfBoundsException();
}
ensureCapacity(size + 1);
System.arraycopy(elementData, index, elementData, index + 1, size - index);
elementData[index] = o;
size++;
}
public Object get(int index){
if (index < 0 || index >= size) {
throw new ArrayIndexOutOfBoundsException();
}
return elementData[index];
}
public Object remove(int index){
if (index < 0 || index >= size) {
throw new ArrayIndexOutOfBoundsException();
}
Object removedItem = elementData[index];
System.arraycopy(elementData, index + 1, elementData, index, size - index - 1);
size--;
return removedItem;
}
public int size(){
return size;
}
public Iterator iterator(){
return new Iterator() {
private int current = 0;
public boolean hasNext() {
return current < size();
}
public Object next() {
if(!hasNext()) {
throw new java.util.NoSuchElementException();
}
return elementData[current++];
}
};
}
}