小伙伴来自己实现一个ArrayList

想来去年实习面试的时候，有公司发来面试题，要求自己实现一个List，当时觉得好难好难，现工作了，有空回来补习一下数据结构，在此与各位小伙伴共勉，望大家多多指教。

代码如下：

package com.david.duan;import java.util.Iterator;import java.util.NoSuchElementException;public class MyArrayList implements Iterable<Student>{//给List设定默认大小private static final int DEFAULT_SIZE = 10;//用于存储list的大小private int size;//原生数组private Student [] students;//构造函数public MyArrayList () {clear ();}private void clear() {size = 0;ensureCapacity(DEFAULT_SIZE);}public int size () {return size;}public boolean isEmplty () {return size() == 0;}public void trimToSize () {ensureCapacity (size());}//返回固定下标的元素public Student get (int idx) {if ( idx < 0 || idx >= size()  )throw new ArrayIndexOutOfBoundsException();return students[idx];}//在固定位置插入元素，并返回之前的元素public Student set (int idx, Student news) {if ( idx < 0 || idx >= size()  )throw new ArrayIndexOutOfBoundsException();Student oldStudent  = students[idx];students[idx] = news;return oldStudent;}//当增加元素到list时，如果数组长度不够，用此扩充大小public void ensureCapacity (int newCapacity) {if (newCapacity < size)return;Student [] oldStudents = students;students = (Student []) new Object[newCapacity];for (int i = 0; i < size(); i++) {students[i] = oldStudents[i];}}public boolean add(Student student) {add(size(), student);return true;}public void add (int idx, Student student) {if (students.length == size())ensureCapacity(size() * 2 +1);for (int i = size; i > idx; i--)students[i] = students [i -1];students [idx] = student;size ++;}//删除元素public Student remove(int idx) {Student removeStudent = students[idx];for (int i = idx; i < size; i++) {students [i] = students[i+1];}size --;return removeStudent;}//实现迭代器接口@Overridepublic Iterator<Student> iterator() {return new ArrayListIterator();}    private class ArrayListIterator implements java.util.Iterator<Student> {    private int current = 0;    @Overridepublic boolean hasNext() {return current < size();}@Overridepublic Student next() {if (!hasNext()) {throw new NoSuchElementException();}return students[current +1];}@Overridepublic void remove() {MyArrayList.this.remove( --current);}        }}

以上的实现基本仿造ArrayList的源码实现，但由于水平有限，很多细节考虑不周，望小伙伴们多多包涵。Collection的API存在某种错误检测以保证合理的限界，为了把精力放在编写迭代器的基本方面，小鸟并没有检测可能使得迭代器结构无效的修改，也没有检测非法的迭代器remove方法。如果有机会，我会在接下来的LinkedList实现中把他完善，谢谢小伙伴们的继续支持。