Compareable接口

重写 compareTo方法如下：

public int compareTo(Object o) {
		Name n = (Name) o;
		int lastCmp = 
				secondName.compareTo(n.secondName);
		return
					(lastCmp!=0 ? lastCmp:firstName.compareTo(n.firstName));
	}

 

完整代码如下

import java.util.List;
import java.util.LinkedList;
import java.util.Collections;
public class Test {
	public static void main(String[] args) {
		List l1 = new LinkedList();
		l1.add(new Name("Karl","M"));
		l1.add(new Name("Steven","Lee"));
		l1.add(new Name("John","O"));
		l1.add(new Name("Tom","M"));
		System.out.println(l1);
		Collections.sort(l1);
		System.out.println(l1);
		
		
		
		
		
		
		
		
		
		/*
		Set s = new HashSet();
		s.add("hello");
		s.add("world");
		s.add(new Name("f1","11"));
		s.add(new Integer(100));
		*/
		
		/*
		
		s.add("hello");
		s.add("hello");
		*/
		//Set 
		/*
		Set s1 = new HashSet();
		Set s2 = new HashSet();
		s1.add("a");s1.add("b");s1.add("c");
		s2.add("d");s2.add("a");s2.add("b");
		Set sn = new HashSet(s1);
		sn.retainAll(s2);
		Set su = new HashSet(s1);
		su.addAll(s2);
		
		System.out.println(sn);
		
		System.out.println(su);
		*/
		
		
		
		
		
		
		
		
		/*
		Collection c = new HashSet();
		c.add("hello");
		c.add(new Name("f1","11"));
		c.add(new Name("f2","12"));
		c.add(new Name("f3","13"));
		c.add(new Integer(100));
		c.remove("hello");
		c.remove(new Integer(100));
		
		Iterator i = c.iterator();
		while(i.hasNext()) {
			Name n = (Name)i.next();
			System.out.print(n.getfirstName()+" ");
		}*/
		/*System.out.println(c.remove(new Name("f1","11")));
		System.out.println(c);*/
	}
}
class Name implements Comparable {
	private String firstName,secondName;
	public Name(String firstName,String secondName) {
		this.firstName = firstName;
		this.secondName = secondName;
	}
	public String getfirstName() {return firstName;}
	public String getsecondName() {return secondName;}
	public String toString() {
		return firstName+" "+secondName;
	}
	
	public boolean equals(Object obj) {
		if(obj instanceof Name) {
			Name name = (Name) obj;
			return (firstName.equals(name.firstName))&&(secondName.equals(name.secondName));
		}
		return super.equals(obj);
	}
	
	public int hashCode() {
		return firstName.hashCode();
	}
	
	public int compareTo(Object o) {
		Name n = (Name) o;
		int lastCmp = 
				secondName.compareTo(n.secondName);
		return
					(lastCmp!=0 ? lastCmp:firstName.compareTo(n.firstName));
	}
}