重读JDK1.8

 

集合排序：Collections.sort

 

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class Test {
    public static void main(String[] args) {
        ArrayList<UserInfo> list = new ArrayList<UserInfo>();
        UserInfo info1 = new UserInfo("A","男",14);
        UserInfo info2 = new UserInfo("B","女",13);
        UserInfo info3 = new UserInfo("C","男",12);
        UserInfo info4 = new UserInfo("F","女",16);
        UserInfo info5 = new UserInfo("D","女",19);
        UserInfo info6 = new UserInfo("E","男",23);
        list.add(info1);list.add(info2);list.add(info3);list.add(info4);list.add(info5);list.add(info6);
        System.out.println("===============排序前===================");
        list.stream().forEach(l->{
            System.out.println(l.toString());
        });
        Collections.sort(list, new Comparator<UserInfo>() {
            @Override
            public int compare(UserInfo o1, UserInfo o2) {
                if(o1.age-o2.age>0){
                    return -1;
                }
                if(o1.age-o2.age<0){
                    return 1;
                }
                return 0;

            }
        });
        System.out.println("===============排序后===================");
        list.stream().forEach(l->{
            System.out.println(l.toString());
        });
    }
}
  class UserInfo{
    String username;
    String sex;
    Integer age;

      public String getUsername() {
          return username;
      }

      public void setUsername(String username) {
          this.username = username;
      }

      public String getSex() {
          return sex;
      }

      public void setSex(String sex) {
          this.sex = sex;
      }

      public Integer getAge() {
          return age;
      }

      public void setAge(Integer age) {
          this.age = age;
      }

      public UserInfo(String username, String sex, Integer age) {
          this.username = username;
          this.sex = sex;
          this.age = age;
      }
      public UserInfo() {
      }

      @Override
      public String toString() {
          return "UserInfo{" +
                  "username='" + username + '\'' +
                  ", sex='" + sex + '\'' +
                  ", age=" + age +
                  '}';
      }

  }

===============排序前===================
UserInfo{username='A', sex='男', age=14}
UserInfo{username='B', sex='女', age=13}
UserInfo{username='C', sex='男', age=12}
UserInfo{username='F', sex='女', age=16}
UserInfo{username='D', sex='女', age=19}
UserInfo{username='E', sex='男', age=23}
===============排序后===================
UserInfo{username='E', sex='男', age=23}
UserInfo{username='D', sex='女', age=19}
UserInfo{username='F', sex='女', age=16}
UserInfo{username='A', sex='男', age=14}
UserInfo{username='B', sex='女', age=13}
UserInfo{username='C', sex='男', age=12}