集合框架--Map集合之TreeMap存储自定义对象

用TreeMap按姓名进行排序：

import java.util.TreeMap;
import java.util.Iterator;
import java.util.Set;
import java.util.Comparator;
import java.util.Map;

class Student {  
	String name;
	int age;

	public Student(String name,int age){
		super();
		this.name=name;
		this.age=age;
	}
	public String getName(){
		return name;
	}
	public void setName(String name){
		this.name=name;
	}
	public int getAge(){
		return age;
	}
	public void setAge(int age){
		this.age=age;
	}
	public int hashCode(){  //复写hashCode()
		return name.hashCode()+age;
	}

	public boolean equals(Object obj){  //复写equals

		if(this==obj) return true;

		if(!(obj instanceof Student))  throw new ClassCastException("类型错误");  //输入类型错误

		Student s = (Student)obj;//强制转换
		return this.name.equals(s.name) && this.age==s.age;  //说明姓名和年龄相同则为同一元素
	}
 
}

class  ComparatorByName implements Comparator{  //按姓名比较,继承Comparator接口
	public int compare(Object o1,Object o2){
		Student s1=(Student)o1;
		Student s2=(Student)o2;
	
		int temp=s1.getName().compareTo(s2.getName());
		return temp==0?s1.getAge()-s2.getAge():temp;
	}
}
public class TreeMapDemo{
	public static void main(String[] args){
		TreeMap<Student,String> tm=new TreeMap<Student,String>(new ComparatorByName());

		tm.put(new Student("lisi",38),"北京");
		tm.put(new Student("zhaosi",34),"上海");
		tm.put(new Student("xiaoqiang",31),"沈阳");
		tm.put(new Student("wangcai",28),"大连");
		tm.put(new Student("zhaosi",34),"铁岭");
	
		Iterator<Map.Entry<Student,String>> it=tm.entrySet().iterator();

		while(it.hasNext()){
			Map.Entry<Student,String> me=it.next();
			Student key=me.getKey();
			String value=me.getValue();
			System.out.println(key.getName()+":"+key.getAge()+"..."+value);
		}
	}

}

运行结果：