package thread1;/*** 实现一个简单的ArrayList** @Title: uminton*/
public class SimpleArrayList<T> {//数组中元素的大小private Integer elementSize = 0;//创建SimpleArrayList时，数组的容量，默认为16private Integer arrayCapacity = 16;//当数组容量不够时，默认每次扩容的大小private static final Integer DEFUALT_EXPAND_SIZE = 16;//元素容器Object[] array = null;//无参数构造，设置默认容量public SimpleArrayList(){this(DEFUALT_EXPAND_SIZE);}/*** 有参数构造，创建容器，设置数组大小* @param arrayCapacity*/public SimpleArrayList(Integer arrayCapacity){super();if(arrayCapacity < 0){throw new IllegalArgumentException("数组空间越界");}array = new Object[arrayCapacity];this.arrayCapacity = arrayCapacity;}/*** 插入一个新元素，如果数组可以放下，直接添加* 如果数组中放不下，扩容* @param v*/public void add(T v){//如果数组可以放下，直接添加if(elementSize < arrayCapacity){array[elementSize++] = v;}else { //如果数组放不下，扩容后再添加arrayCapacity += DEFUALT_EXPAND_SIZE; //扩容System.out.println("数组放不下扩容:"+arrayCapacity);Object[] newArray = new Object[arrayCapacity];//创建新的数组System.arraycopy(array,0,newArray,0,array.length);//拷贝数据到新的数组array = newArray;//从新的数组赋值到原数组array[elementSize++] = v;//添加}}/*** 根据指定下标查找元素* @param index* @return*/public T get(int index){if(index > elementSize-1 || index < 0){throw new ArrayIndexOutOfBoundsException(index);}return (T) array[index];}/*** 删除指定位置的元素，所有之后的元素需要前移* @param index*/public void remove(int index){if(index > elementSize-1 || index < 0){throw new ArrayIndexOutOfBoundsException(index);}for (int i = index; i < elementSize-1; i++) {array[i] = array[i+1];  //覆盖前一个数据}elementSize--;}/*** 更新指定位置上的元素* @param index* @param t*/public void update(int index,T t){if(index > elementSize-1 || index < 0){throw new ArrayIndexOutOfBoundsException(index);}array[index] = t;}/*** 返回array中元素的大小* @return*/public Integer size(){return elementSize;}public Integer capacity(){return arrayCapacity;}public static void main(String[] args) {SimpleArrayList<Integer> list = new SimpleArrayList<>();//添加for (int i = 0; i < 20; i++) {list.add(i);}//遍历for (int i = 0; i < list.size(); i++) {System.out.print(list.get(i)+" ");}//删除index为10的元素list.remove(10);for (int i = 0; i < list.size(); i++) {System.out.println("index:"+i+";value:"+list.get(i));}System.out.println("size:" + list.size() + ",capacity:" + list.capacity());}}