1.13 设计一个泛型类Collection

要求：设计一个泛型类Collection，它存储object对象的集合（在数组中），
以及该集合当前的大小。提供public方法isEmtpy，makeEmpty,insert,remove,isPresent.方法isPresent(x)当且仅当在集合中存在（由equals定义） 等于x的一个object时返回true

import java.util.Arrays; /** * 可以用 * @author 疯狂龅牙酥 * */ public class One_thirteen {  public static void main(String[] args) {  // TODO Auto-generated method stub Object[] obj = new Object[] { "9"}; Collection<String> cool = new Collection<String>(obj); System.out.println(Arrays.toString(cool.getCollection())); System.out.println(cool.getSize()); System.out.println(cool.isEmpty()); System.out.println(cool.getSize()); cool.makeEmpty(); System.out.println(cool.isEmpty()); System.out.println(cool.getSize()); cool.insert("1"); cool.insert("2"); cool.insert("3"); System.out.println(Arrays.toString(cool.getCollection())); System.out.println(cool.getSize()); cool.remove(2); System.out.println(Arrays.toString(cool.getCollection())); System.out.println(cool.getSize()); System.out.println(cool.isPresent("3")); } } class Collection<Value> {  private Object[] arr; private int size = 0; // 0为空 public Collection(Object[] arr) {  this.size = arr.length; this.arr = arr; } public int getSize() {  return this.size; } public Object[] getCollection() {  return this.arr; } public boolean isEmpty() {  return this.size == 0; } public void makeEmpty() {  this.size = 0; // 这里应该把数组清空 this.arr = new Object[] { }; } public void insert(Value insertedValue) {  if (this.size > this.arr.length + 1) {  // 还能装 this.arr[this.size++] = insertedValue; } else {  // 装不下了，需要开辟空间 // 先开辟一块更大的，然后替换掉原来的，原来的系统会自动回收垃圾空间 Object[] tmp = new Object[this.size + 1]; System.arraycopy(this.arr, 0, tmp, 0, this.size++); tmp[this.size - 1] = insertedValue; this.arr = tmp; } } public void remove(int index) {  if(index < 0 || index > this.size-1) {  return; } if(index < this.size-1) {  for(int i=index; i<this.size-1; i++) {  this.arr[i] = this.arr[i+1]; } } Object[] tmp = new Object[this.size-1]; System.arraycopy(this.arr, 0, tmp, 0, index); System.arraycopy(this.arr, index+1, tmp, index, this.size-1-index); this.arr = tmp; this.size--; } public boolean isPresent(Value v) {  for(Object vi:this.arr) {  if(vi.equals(v)) {  return true; } } return false; } }