hashSet

package hashSet;
import java.util.*;

public class CollectionsTest
{
	 public static void main(String[] args)
	 {
	    ArrayList hs=new ArrayList();
		hs.add(new Student(3,"main",23));
		hs.add(new Student(4,"lili",21));
		hs.add(new Student(2,"lucy",25));
		hs.add(new Student(1,"mali",23));
		hs.add(new Student(5,"xuanzi",22));
		Object o=Collections.max(hs);
		System.out.println("最大值:"+o);
		
		Collections.reverse(hs);
		System.out.println("反序:"+hs);
		System.out.println("自然排序：(Comparable)");
		System.out.println(hs);
		Collections.sort(hs,new MyComparator());
		System.out.println("比较器排序:(Comparator)");
		System.out.println(hs);
		Comparator reverse=Collections.reverseOrder(new MyComparator());
		System.out.println("反转比较器排序(Comparator):");
		System.out.println(hs);
		
	 }
}

 

package hashSet;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import a1.Book;
public class HashSetTest
{
	public static void main(String[] args)
	{
		HashSet hs=new HashSet();
		ArrayList l=new ArrayList();
		hs.add(1);
		hs.add(1);
		hs.add(new Book(1,"apple"));
		hs.add(new Book(1,"apple"));
		l.add(new Book(1,"apple"));
		l.add(new Book(1,"apple"));
	    Iterator it=hs.iterator();	//声明迭代器
	    while(it.hasNext())
	    {
	    	Object o=it.next();
	    	if(o instanceof Book)
	    	{
	    	  ((Book) o).setId(100);//修改id的值
	    	  ((Book) o).setName("Java");//修改id的值
	    	}
	    	 
	    }
	    System.out.println(hs);
	    it.remove();
	   // it.remove();
	
	    System.out.println(hs);
	    System.out.println("调用通用迭代器:");
	    foreach(hs);
	    foreach(l);
	}
	//通用迭代器
	public static void foreach(Collection s)
	{
		Iterator it=s.iterator();
		while(it.hasNext())
		{
			Object o=it.next();
		}
		System.out.println(s);
	}
}

 

package hashSet;

import java.lang.reflect.Method;
import java.util.Comparator;

public class MyComparator implements Comparator
{
	@Override
	public int compare(Object o1, Object o2)
	{
		//获取类的自描述对象
        Class c1=o1.getClass();
        Class c2=o2.getClass();
        //Field f1,f2;
        Method m1,m2;
        Integer id1=null,id2=null;
        try
		{
        //获取字段的自描述对象
		 //f1=c1.getDeclaredField("id");
		 //f2=c2.getDeclaredField("id");
		 //id1=f1.getInt(o1);
		 //id2=f2.getInt(o2);
		 //返回get方法的描述对象
		 m1=c1.getDeclaredMethod("getId");
		 m2=c2.getDeclaredMethod("getId");
		 id1=(Integer) m1.invoke(o1);
		 id2=(Integer) m2.invoke(o2);
		 //从对象中得到字段值
		 
		} catch (Exception e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
		return id1.compareTo(id2);
		
	}

}

 

package hashSet;

public class Student implements Comparable
{
  private int id;
  private String name;
  private int age;
public Student(int id,String name, int age)
{
	super();
	this.id=id;
	this.name = name;
	this.age = age;
}

public int getId()
{
	return id;
}

public void setId(int id)
{
	this.id = id;
}

@Override
public String toString()
{
	// TODO Auto-generated method stub
	return "编号:"+id+"姓名:"+name+"年龄:"+age;
}
@Override
public int compareTo(Object o)
{
	// TODO Auto-generated method stub
	Student s=(Student) o;
	return ((Integer)this.age).compareTo(s.age);
}

}

 

package hashSet;

import java.util.HashSet;
import java.util.TreeSet;

import a1.Book;

public class TreeSetTest
{
public static void main(String [] args)
	{
		HashSet hs=new HashSet();
		//hs.add(1);
		Book b1=new Book(1,"apple",100);
		Book b2=new Book(3,"pear",100);
		Book b3=new Book(2,"pear",200);
		Book b4=new Book(4,"pear",300);
		Book b5=new Book(5,"pear",50);
		hs.add(b1);
		hs.add(b2);
		hs.add(b3);
		hs.add(b4);
		hs.add(b5);
		TreeSet ts=new TreeSet(hs);
		System.out.println(ts);
		System.out.println("hs:"+hs);
	
	}
}