Java基础之泛型限定的使用示例：

import java.util.*;
class GenericDemo
{
    public static void main(String[] args)
    {
        TreeSet<Person> ts = new TreeSet<Person>(new MyComparator());
        
        ts.add(new Person("张三","男",28,175));
        ts.add(new Person("李四","女",28,160));
        ts.add(new Person("王五","女",27,185));
        ts.add(new Person("麻六","男",38,174));
        
        PrintSet(ts);
        
        TreeSet<Student> stu = new TreeSet<Student>(new MyComparator());
        
        stu.add(new Student("张三","男",28,175,8.9));
        stu.add(new Student("李四","女",28,160,8.8));
        stu.add(new Student("王五","女",27,185,8.8));
        stu.add(new Student("麻六","男",38,174,9.0));
        
        PrintSet(stu);
        
        TreeSet<Worker> wk = new TreeSet<Worker>(new MyComparator());
        
        wk.add(new Worker("张三","男",28,175,8.92));
        wk.add(new Worker("李四","女",28,160,8.83));
        wk.add(new Worker("王五","女",27,185,8.84));
        wk.add(new Worker("麻六","男",38,174,9.05));
        
        PrintSet(wk);
    }
    
    public static void PrintSet(TreeSet<? extends Person> set)
    {
        for(Iterator<? extends Person> it = set.iterator();it.hasNext();)
        {
            Person p = it.next();
            System.out.println(p.getName()+"\t"+p.getSex()+"\t"+p.getAge()+"\t"+p.getHeight());
        }
    }
    
    /*
    public static void PrintSet(TreeSet<? super Student> set)
    {
        for(Iterator<? super Student> it = set.iterator();it.hasNext();)
        {
            Person p = (Person)it.next();
            System.out.println(p.getName()+"\t"+p.getSex()+"\t"+p.getAge()+"\t"+p.getHeight());
        }
    }
    */
}

class MyComparator implements Comparator<Person> 
{
    public int compare(Person p1,Person p2)
    {
        if(p2.getName().equals(p1.getName()))
        {
            if(p2.getAge()==p1.getAge())
            {
                return 0;
            }
        }
        
        return p2.getName().compareTo(p1.getName());
    }
}

class Person implements Comparable
{
    private String name;
    private String sex;
    private int age;
    private int height;
    
    public Person(String name,String sex,int age,int height)
    {
        this.name = name;
        this.sex = sex;
        this.age = age;
        this.height = height;
    }
    
    public void setName(String name)
    {
        this.name = name;
    }
    
    public String getName()
    {
        return this.name;
    }
    
    public void setSex(String sex)
    {
        this.sex = sex;
    }
    
    public String getSex()
    {
        return this.sex;
    }
    
    public void setAge(int age)
    {
        this.age = age;
    }
    
    public int getAge()
    {
        return this.age;
    }
    
    public void setHeight(int height)
    {
        this.height = height;
    }
    
    public int getHeight()
    {
        return this.height;
    }
    
    public int compareTo(Object obj)
    {
        if(!(obj instanceof Person))
            return -1;
            
        Person p = (Person)obj;
        int number = this.getName().compareTo(p.getName());
        if(number==0)
        {
            return this.getAge() - p.getAge();
        }
        
        return number;
    }
    
    public int hashCode()
    {
        return this.getName().hashCode()+this.getAge()*21;
    }
    
    public boolean equals(Object obj)
    {
        if(!(obj instanceof Person))
            return false;
            
        Person p = (Person)obj;
        
        return (p.getName().equals(this.getName()) && p.getAge()==this.getAge());
    }
}

class Student extends Person
{
    private double score;
    public Student(String name,String sex,int age,int height,double score)
    {
        super(name,sex,age,height);
        this.score = score;
    }
    
    public void setScore(double score)
    {
        this.score = score;
    }
    
    public double getScore()
    {
        return this.score;
    }
}

class Worker extends Person
{
    private double pay;
    public Worker(String name,String sex,int age,int height,double pay){
        super(name,sex,age,height);
        this.pay = pay;
    }
    
    public void setPay(double pay)
    {
        this.pay = pay;
    }
    
    public double getPay()
    {
        return this.pay;
    }
}