自己实现一个ArrayList，模仿ArrayList类的底层结构

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/** * 自己实现一个ArrayList，模仿ArrayList类的底层结构！ */public class MyArrayList{    private Object[] elementData;    private int size;    public MyArrayList() {        this(10);    }    public MyArrayList(int initialCapacity) {        if (initialCapacity < 0) {            try {                if (initialCapacity < 0)                    throw new IllegalArgumentException("错错错，容量不能小于0");            } catch (Exception e) {                e.printStackTrace();            }        }        // 初始化数组        elementData = new Object[initialCapacity];    }    public void add(Object obj) {        // 数组扩容和数据的拷贝        if (size == elementData.length) {            Object[] newArray = new Object[size * 2 + 1];            // 数组拷贝            // arraycopy(Object src, int srcPos, Object dest, int destPos, int            // length)            // System.arraycopy(elementData, 0, newArray, 0,            // elementData.length);            for (int i = 0; i < elementData.length; i++) {                newArray[i] = elementData[i];            }            elementData = newArray;        }        elementData[size++] = obj;    }    public void add(int index, Object obj) {        rangeCheck(index);        ensureCapacity(); // 数组扩容        System.arraycopy(elementData, index, elementData, index + 1, size                - index);        elementData[index] = obj;        size++;    }    public Object get(int index) {        rangeCheck(index);        return elementData[index];    }    public void remove(int index) {        rangeCheck(index);        // 删除指定位置的对象        // a b d e        int numMoved = size - index - 1;        if (numMoved > 0) {            System.arraycopy(elementData, index + 1, elementData, index,                    numMoved);        }        elementData[--size] = null; // Let gc do its work    }    public void remove(Object obj) {        for (int i = 0; i < size; i++) {            if (get(i).equals(obj)) { // 注意：底层调用的equals方法而不是==.                remove(i);            }        }    }    public Object set(int index, Object obj) {        rangeCheck(index);        Object oldValue = elementData[index];        elementData[index] = obj;        return oldValue;    }    private void ensureCapacity() {        // 数组扩容和数据的拷贝        if (size == elementData.length) {            Object[] newArray = new Object[size * 2 + 1];            System.arraycopy(elementData, 0, newArray, 0, elementData.length);            // for(int i=0;i<elementData.length;i++){            // newArray[i] = elementData[i];            // }            elementData = newArray;        }    }    private void rangeCheck(int index) {        if (index < 0 || index >= size) {            try {                throw new IndexOutOfBoundsException("数组下标越界啦！");            } catch (Exception e) {                e.printStackTrace();            }        }    }    public int size() {        return size;    }    public boolean isEmpty() {        return size == 0;    }    public static void main(String[] args) {        MyArrayList list = new MyArrayList(3);        list.add("333");        list.add("444");        list.add("5");        list.add("344433");        list.add("333");        list.add("333");        System.out.println(list.size());        list.remove("444");        System.out.println(list.size());    }}
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