Collections 排序
1.Collections排序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; }}
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