java实现ArrayList顺序表

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import java.util.Arrays;/** * 模拟ArrayList实现自己的顺序表 *@author 莱格 */public class MyArrayList {    private Object[] elementData;    private int size;//容器的大小    //返回容器的大小    public int size() {        return size;    }    //判断list是否为空    public boolean isEmpty() {        return size == 0;    }    //初始化容器的大小    public MyArrayList(int initialCapacity) {        if(initialCapacity < 0) {            try {                throw new Exception();            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        elementData = new Object[initialCapacity];    }    public MyArrayList() {        this(10);    }    //添加元素    public void add(Object obj) {        //数组扩容        if (size == elementData.length) {            Object[] newArray = new Object[2*size+1];            //System.arraycopy(src, srcPos, dest, destPos, 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);//检查索引        ensureCapacity();//数组扩容        System.arraycopy(elementData, index, elementData, index+1, size-index);        elementData[index] = obj;        size++;    }    //获得指定位置的元素    public Object get(int index) {        rangeCheck(index);        System.out.println(elementData[index]);        return elementData[index];    }    //删除指定位置的对象    public void remove(int index) {        rangeCheck(index);//      if(index < 0 || index >= size) {//          try {//              throw new Exception();//          } catch (Exception e) {//              // TODO Auto-generated catch block//              e.printStackTrace();//          }            int numMoved = size-index-1;            if(numMoved>0) {                System.arraycopy(elementData, index+1, elementData, index, numMoved);            }            elementData[--size] = null;//垃圾回收        }    //删除指定元素    public void remove(Object obj) {        for (int i = 0; i < size; i++) {            if (get(i).equals(obj)) {                remove(i);            }        }    }    public Object set(int index,Object obj) {        rangeCheck(index);        Object oldValue = elementData[index];        elementData[index] = obj;        return oldValue;    }    /**     * 数组扩容     */    private void ensureCapacity() {        if(size == elementData.length) {            Object[] newArray = new Object[size*2+1];            System.arraycopy(elementData, 0, newArray, 0, elementData.length);            elementData = newArray;        }    }    /**     * @param index     */    private void rangeCheck(int index) {        if (index<0 || index >= size) {            try {                throw new Exception();            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }    }    //打印数组    public String toString() {        //System.out.println(elementData.toString());        return Arrays.toString(elementData);    }    //测试    public static void main(String[] args) {        MyArrayList slist = new MyArrayList(3);        slist.add(132);        slist.add(132);        slist.add("444");        slist.add(5);        slist.add("333");        slist.add("333");        slist.add("abc");        slist.add("ccc");        slist.toString();        System.out.println(slist.size);        System.out.println(slist.get(6));        slist.remove(3);        System.out.println(slist.size);    }}
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