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;
	}
	
}