Collectionsソート
1.Collectionsソート
import java.util.*;
public class ArrayListTest {
public static void printElements(Collection c){
Iterator it=c.iterator();
while(it.hasNext()){
System.out.println(it.next());
}
}
public static void main(String[] args){
ArrayList a1=new ArrayList();
Student s1=new Student(4,"zhangsan");
Student s2=new Student(2,"lisi");
Student s3=new Student(3,"wangwu");
Student s4=new Student(4,"mybole");
a1.add(s1);
a1.add(s2);
a1.add(s3);
a1.add(s4);
Collections.sort(a1);
// Collections.sort(a1,new Student.StudentComparator());
printElements(a1);
System.out.println(Collections.max(a1));
}
}
class Point{
int x, y;
Point(int x,int y){
this.x=x;
this.y=y;
}
public String toString(){
return ("x="+x+","+"y="+y);
}
}
class Student implements Comparable{
int num;
String name;
Student(int num,String name){
this.num=num;
this.name=name;
}
static class StudentComparator implements Comparator{
public int compare(Object o1,Object o2){
Student s1=(Student) o1;
Student s2=(Student) o2;
int result=s1.num>s2.num?1:(s1.num==s2.num?0:-1);
if (result==0){
result=s1.name.compareTo(s2.name);
}
return result;
}
}
public int compareTo(Object arg0) {
Student s=(Student) arg0;
return num>s.num?1:(num==s.num?0:-1);
}
public String toString(){
return "num:"+num+","+"name:"+name;
}
}