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();
}
}