java中list<Object[]>、list<Student>、list<Map<String,String>>排序

1：list<Object[]>的排序

public static void main(String[] args) {
// TODO Auto-generated method stub
Object[] o1=new Object[4];
o1[0]="5";
o1[1]="o1";
o1[2]="o11";
o1[3]="o111";
Object[] o2=new Object[4];
o2[0]="3";
o2[1]="o2";
o2[2]="o22";
o2[3]="o222";
List<Object[]> list=new ArrayList<>();
list.add(o1);
list.add(o2);

//很明显我们先添加的对象o1，所以先打印o1，

for(inti=0;i<list.size();i++){
for(intj=0;j<4;j++){
System.out.print(list.get(i)[j]+" ");
}
}
System.out.println("\n排序后-------");
sortList(list);

//排序后：

for(inti=0;i<list.size();i++){
for(intj=0;j<4;j++){
System.out.print(list.get(i)[j]+" ");
}
}

写一个方法

public staticvoid sortList(List<Object[]>ls){
Collections.sort(ls,new Comparator<Object[]>() {
@Override
public int compare(Object[] o1, Object[] o2) {
if(Integer.valueOf(o1[0].toString())>Integer.valueOf(o2[0].toString()))
{
return 1;
}
return -1;
}
});
}

2：//list<Student>排序，主要是正对汉族的排序，按照拼音排序，

首先写一个Student类：

package com.model;

public class Student {
public Stringname;
publicintage;
public Student(Stringname,intage){
this.name=name;
this.age=age;
}
public void setName(String name){
this.name=name;
}
public String getName(){
returnname;
}
public void setAge(int age){
this.age=age;
}
public int getAge(){
returnage;
}
}

然后在main方法中调用，（这里写的是一个java文件）

Student stu1=new Student("张三",23);
Student stu2=new Student("李四",25);
List<Student> listStudent=new ArrayList<>();
listStudent.add(stu1);
listStudent.add(stu2);

System.out.println();
for(int i=0;i<listStudent.size();i++){
System.out.print(listStudent.get(i).getName()+"---"+listStudent.get(i).getAge());
}
System.out.println("\n排序后");
sortListStudent(listStudent);
for(int i=0;i<listStudent.size();i++){
System.out.print(listStudent.get(i).getName()+"---"+listStudent.get(i).getAge());
}

写一个排序方法

public staticvoid sortListStudent(List<Student>ls){
Collections.sort(ls,new Comparator<Student>() {

@Override
public int compare(Student o1, Student o2) {
String s1=o1.getName();
String s2=o2.getName();
if(s1.compareTo(s2)>0){
return -1;
}
return 1;
}
});

}

}

结果图：



3：list<Map<String,String>>排序问题：

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MapListSort {

public static void main(String[] args) {
// TODO Auto-generated method stub
List<Map<String,String>> listMap=new ArrayList<>();
Map<String, String> map1=new HashMap<String, String>();
map1.put("map001", "001");
map1.put("map003", "map003");
map1.put("map002", "map002");
Map<String, String> map2=new HashMap<String, String>();
map2.put("map001", "101");
map2.put("map003", "map303");
map2.put("map002", "map202");
//先添加的map2，但是map2中map001的值大于map1中的map001的值。
listMap.add(map2);
listMap.add(map1);

for(int i=0;i<listMap.size();i++){
System.out.print(listMap.get(i).get("map001")+","+listMap.get(i).get("map002")+","+listMap.get(i).get("map003")+"\n");

}

mapSorts(listMap);

System.out.println("\n排序后：");
for(int i=0;i<listMap.size();i++){
System.out.print(listMap.get(i).get("map001")+","+listMap.get(i).get("map002")+","+listMap.get(i).get("map003")+"\n");
}
}

public static void mapSorts(List<Map<String,String>> map){
Collections.sort(map,new Comparator<Map<String,String>>() {

@Override
public int compare(Map<String, String> o1, Map<String, String> o2) {
// TODO Auto-generated method stub
if(o1.get("map001").compareTo(o2.get("map001"))>0){
return 1;
}
return -1;
}
});
}
}