刚学到Comparable 接口 , 出现了点小问题 求指点
程序代码：import java.util.*;
public class TestComparable{
public static void main(String args[]){
List l = new ArrayList();
l.add(new testname("Giggs","wong") );
l.add(new testname("beckham","li") );
l.add(new testname("jack","chen") );
l.add(new testname("suki","xu") );
Collections.reverse(l);
System.out.println(l);
Collections.sort(l); // 排序testname 类 // 怎么老出现异常
System.out.println(l);
}
}
class testname{
public String firstname;
public String lastname;
testname(String f,String l){
firstname = f;
lastname = l;
}
public int compareTo(Object o){
testname t = (testname) o;
int bo = (t.lastname);
return ( bo !=0 ? bo : (t.firstname) );
}
public String toString(){
return lastname+" "+firstname;
}
}
