模拟java.util.Collection一些简单的用法

/*
需求：模拟java.util.Collection一些简单的用法！

注意：java虚拟机中并没有泛型类型的对象。泛型是通过编译器执行一个被称为类型擦除的前段转换来实现的。
1）用泛型的原生类型替代泛型。
原生类型是泛型中去掉尖括号及其中的类型参数的类或接口。泛型中所有对类型变量的引用都替换为类型变量的最近上限类型，
如对于Cage<T extends Animal>, T的引用将用Animal替换，而对于Cage<T>, T 的引用将用Object替换。

2）
*/
interface Collection<T>{
    public abstract void add(T o);
	public abstract Object getElement(int index);
	public abstract void setElement(int index, T o);
	public abstract Object[] toArray();
	public abstract boolean isNext();
	public abstract Object nextElemenst();
}

class Array<T> implements Collection<T>{
	 int buildNum = 10;
	 int maxSize = 10;
	 int size = 0;
	 int flag = 0;
	 int xIndex;
     Object[] elementsData = new Object[maxSize];
	 /*
	    判断时候数组大小不够
	 */
	 public void isFullSize(){
	    if(maxSize == size){
		   Object[] tmp = new Object[maxSize += buildNum];
		   for(int i=0; i<size; ++i)
		       tmp[i] = elementsData[i];
		   elementsData = tmp;
		}
	 }
	 //添加元素
     public void add(T o){
	     isFullSize();
         elementsData[size++] = o;
	 }

	 //得到某一个下标的元素
	 public Object getElement(int index){
	      if(index < size){
			    System.out.println(elementsData[index].getClass().getName());
			    return elementsData[index];
		  }
		  else return null;
	 }
	 //获取某一个元素的下标
	 public int getIndex(T o){
	      for(int i=0; i<size; ++i)
		     if(o.equals(elementsData[i]))
			    return i;
		  return -1;
	 }
	 //设置某个元素为一新值
	 public void setElement(int index, T o){
	     if(index < size)
		     elementsData[index] = o;
	 }
	 //放回对象数组
	 public Object[] toArray(){
	      return elementsData;
	 }
	 //是否有下一个元素
	 public boolean isNext(){
	     if(flag == 0){
		     flag =1;
			 xIndex=0;
		 }
		 if(xIndex == size){
			     flag = 0;
				 return false;
		 }

		 return true;
	 }
	 //返回下一个元素
	 public Object nextElemenst(){
	     return elementsData[xIndex++];
	 }

	 public static void qsort(Object arr[], int from, int to){
	    //@SuppressWarnings("unchecked")
		if(from >= to) return;
		int mid = (from+to)/2;
        Object pivotkey = arr[from];
		if(arr[from] instanceof Comparable){
		   System.out.println("dfsdfsdf");
		   Comparable pp = (Comparable)arr[from];
		}
		if( ((Comparable)arr[mid]).compareTo(arr[from]) * ((Comparable)arr[mid]).compareTo(arr[to])<0){
		    arr[from] = arr[mid];
			arr[mid] = pivotkey;
		}
		else if( ((Comparable<Object>)arr[to]).compareTo(arr[from]) * ((Comparable<Object>)arr[to]).compareTo(arr[mid])<0){
		    arr[from] = arr[to];
			arr[to] = pivotkey;
		}
		pivotkey = arr[from];
		int low = from, high = to;
		while(low < high){
		    while(low < high && ((Comparable<Object>)arr[low]).compareTo(pivotkey)>0)  ++low;
		    while(low < high && ((Comparable<Object>)arr[high]).compareTo(pivotkey)<0)  --high;

			if(low < high){
			   Object tmp = arr[low];
			   arr[low] = arr[high];
			   arr[high] = tmp;
			}
		}
		 arr[low] = pivotkey;
		 qsort(arr, from, low-1);
		 qsort(arr, low+1, to);
     }
}

class Person implements Comparable<Person>{
   String name;
   int age;
   Person(){
       name = "";
	   age = 0;
   }
   Person(String name, int age){
       this.name = name;
	   this.age = age;
   }
   public String toString(){
       return name + "...." + age;
   }

   public boolean equals(Object o){
       Person x = (Person)o;
	   return name.equals(x.name) && age==x.age;
   }

   public int compareTo(Person o){
       if(name.compareTo(o.name)==0)
	      return age - o.age;
	   return name.compareTo(o.name);
   }
}

class ArrayList<T>{
     Object elementsData[] = null;
	 int size = 0;
     ArrayList(Collection<T> x){
	     elementsData = x.toArray();
		 for(int i=0; i<elementsData.length; ++i){
		    if(elementsData[i]==null)
			    break;
			++size;//不计入空引用
		 }
	 }
	 public void MaxToMinSort(){//从大到小排序
	      Array.qsort(elementsData, 0, size-1);
	 }

	 public void output(){
	     for(int i=0; i<size; ++i)
		    System.out.println(elementsData[i]);
	 }
}
public class Test{
   public static void main(String[] args){
		Array<Person>arr = new Array<Person>();
		for(int i=0; i<15; ++i)
		   arr.add(new Person("h" + i + 1, i+1));

		System.out.println("Array 中的数据。。。。。");
		while(arr.isNext()){
		    System.out.println( ((Person)arr.nextElemenst()) );
		}
		System.out.println(arr.getIndex(new Person("h101", 11)));
		System.out.println(arr.getElement(5));
		System.out.println("*******************************************************\nArrayList中排好序的数据！");

		ArrayList<Person> arrT = new ArrayList<Person>(arr);
		arrT.MaxToMinSort();
		arrT.output();
    }
}

模拟java.util.Collection一些简单的用法