1 package day16;
  2 
  3 import java.util.ArrayList;
  4 import java.util.Collections;
  5 import java.util.Comparator;
  6 import java.util.List;
  7 import java.util.function.Function;
  8 import java.util.function.ToDoubleFunction;
  9 import java.util.function.ToIntFunction;
 10 import java.util.function.ToLongFunction;
 11 
 12 public class Test7 {
 13     public static void main(String[] args){
 14         List<String> list = new ArrayList<String>();
 15         list.add("b");
 16         list.add("cd");
 17         list.add("ca");
 18         list.add("a");
 19         list.add("a");
 20         list.add("1");
 21         
 22         System.out.println(list);
 23         
 24         Collections.reverse(list);//反转List中元素的顺序。
 25         System.out.println(list);
 26         
 27         Collections.shuffle(list);//对List集合元素进行随机排序。
 28         System.out.println(list);
 29         
 30         Collections.sort(list);//list集合字典升序排序
 31         System.out.println(list);
 32         
 33         System.out.println(Collections.frequency(list, "a"));//返回指定集合中指定元素的出现次数。
 34         
 35         Collections.replaceAll(list, "b", "bb");
 36         System.out.println(list);
 37         
 38         Collections.swap(list, 0, 4);//将指定list集合中的i处元素进行交换。
 39         System.out.println(list);
 40         
 41         System.out.println(Collections.max(list));//根据元素的自然顺序，返回给定集合中的最大元素。
 42         System.out.println(Collections.min(list));
 43         
 44         
 45         
 46         Student s1 = new Student(14,"张三");
 47         Student s2 = new Student(12,"李四");
 48         Student s3 = new Student(13,"王五");
 49         Student s4 = new Student(11,"马六");
 50         
 51         List<Student> stus = new ArrayList<Student>();
 52         stus.add(s1);
 53         stus.add(s2);
 54         stus.add(s3);
 55         stus.add(s4);
 56         
 57         Student s = Collections.max(stus,new Student());//根据Commparator指定的顺序，返回给定集合中的最大元素。
 58         System.out.println(s.name + "," +s.age);
 59         
 60         Student ss = Collections.min(stus,new Student());
 61         System.out.println(ss.name + "," +ss.age);
 62         
 63 //        for(Student stu:stus){
 64 //            System.out.println(stu.name + "," + stu.age);
 65 //        }
 66 //        
 67 //        System.out.println("-----------------");
 68 //        
 69 //        Collections.sort(stus,new Student());
 70 //        for(Student stu:stus){
 71 //            System.out.println(stu.name + "," + stu.age);
 72 //        }
 73     }
 74 }
 75 
 76 class Student implements Comparator<Student>{
 77     int age;
 78     String name;
 79     public Student(){
 80         
 81     }
 82     
 83     public Student(int age,String name){
 84         this.age = age;
 85         this.name = name;
 86     }
 87     
 88 
 89     public int compare(Student o1, Student o2) {//根据年龄升序排列对象
 90         // TODO Auto-generated method stub
 91         if(o1.age > o2.age){
 92             return 1;
 93         }else if(o1.age < o2.age){
 94             return -1;
 95         }else{
 96             return 0;
 97         }
 98 
 99     }
100 
101 }