Java 中 泛型的限定

package stu.love.v;

import java.util.*;

//泛型限定上限的应用

class Demo12 
{
	public static void main(String[] args) 
	{
		

		Collection<Student> c = new ArrayList<Student>();

		c.add(new Student("zhaosi",23));
		c.add(new Student("lisi",25));
		c.add(new Student("wangwu",20));
     
	   //TreeSet(Collection<? extends E> c)
	   // class TreeSet<E>
	   //{
	   //}
		TreeSet<Person> ts = new TreeSet<Person>(c);

		Iterator<Person> ite = ts.iterator();
		while(ite.hasNext())
		{
			sop(ite.next());
		}
	}
	
	public static void sop(Object obj)
	{
		System.out.println(obj);
	}
}

package stu.love.v;

import java.util.*;

import stu.love.v.Demo11;

/*// 子类 特殊的 比较器  Student
class ComByAge implements Comparator<Student>
{
	public int compare(Student s1,Student s2)
	{
		int num = new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));
		if(num==0)
			return s1.getName().compareTo(s2.getName());
		return num;
	}
}

// 子类 特殊的 比较器 Teacher
class ComByAge2 implements Comparator<Teacher>
{
	public int compare(Teacher s1,Teacher s2)
	{
		int num = new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));
		if(num==0)
			return s1.getName().compareTo(s2.getName());
		return num;
	}
}*/

//父类的比较器   <Person>
class CompareByAge implements Comparator<Person>
{
	public int compare(Person s1,Person s2)
	{
		int num = new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));
		if(num==0)
			return s1.getName().compareTo(s2.getName());
		return num;
	}

}

class Demo13 
{
	//TreeSet<E>(Comparator<? super E> comparator) 定义比较器时，可以是E类型，还可以是E的父类型,E在创建集合对象时确定
	public static void main(String[] args) 
	{
		TreeSet<Student> t1 = new TreeSet<Student>(new CompareByAge());
		t1.add(new Student("zhaosi",23));
		t1.add(new Student("lisi",25));
		t1.add(new Student("wangwu",20));


		TreeSet<Teacher> t2 = new TreeSet<Teacher>(new CompareByAge());
		t2.add(new Teacher("wang",38));
		t2.add(new Teacher("lilaoshi",48));
		t2.add(new Teacher("zhanglaoshi",58));
	}
	

}