看了一下，好像有两种方法，第一个是实例化一个比较器，例子如下
public class Student {
private int studentId;
private String studentName;
private int age;
public Student(int studentId , String studentName, int age){
this.studentId=studentId;
this.studentName=studentName;
this.age=age;
}
public int getStudentId() {
return studentId;
}
public void setStudentId(int studentId) {
this.studentId = studentId;
}
public String getStudentName() {
return studentName;
}
public void setStudentName(String studentName) {
this.studentName = studentName;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class test {
/**
* @param args
*/
public static void main(String[] args) {
Comparator<Student> comparator = new Comparator<Student>() {
public int compare(Student s1, Student s2) {
// 先排年龄
if (s1.getAge() != s2.getAge()) {
return s1.getAge() - s2.getAge();
} else if (!s1.getStudentName().equals(s2.getStudentName())) {
// 年龄相同则按姓名排序
return s1.getStudentName().compareTo(s2.getStudentName());
} else {
// 姓名也相同则按学号排序
return s1.getStudentId() - s2.getStudentId();
}
}
};
Student stu1 = new Student (1,"zhangsan",28);
Student stu2 = new Student (2,"zhagnsan",19);
Student stu3 = new Student (3,"wangwu",19);
Student stu4 = new Student (4,"wangwu",19);
Student stu5 = new Student (5,"zhaoliu",18);
ArrayList<Student> list = new ArrayList<Student>();
list.add(stu1);
list.add(stu2);
list.add(stu3);
list.add(stu4);
list.add(stu5);
//这里就会自动根据规则进行排序
Collections.sort(list,comparator);
for(int i=0;i<list.size();i++){
Student stu=list.get(i);
System.out.println("年龄:"+stu.getAge()+" 姓名:"+stu.getStudentName()+" 学号:"+stu.getStudentId());
}
}
}
第二个是实现Comparable接口
public class Student2 implements Comparable<Student2>{
private int studentId;
private String studentName;
private int age;
public Student2(int studentId , String studentName, int age){
this.studentId=studentId;
this.studentName=studentName;
this.age=age;
}
public int getStudentId() {
return studentId;
}
public void setStudentId(int studentId) {
this.studentId = studentId;
}
public String getStudentName() {
return studentName;
}
public void setStudentName(String studentName) {
this.studentName = studentName;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public int compareTo(Student2 o) {
if(age!=o.getAge()){
return age-o.getAge();
}else if(!studentName.equals(o.getStudentName())){
return studentName.compareTo(o.getStudentName());
}else {
return studentId-o.getStudentId();
}
}
@Override
public boolean equals(Object obj) {
if(obj instanceof Student2){
Student2 stu=(Student2)obj;
if((age==stu.getAge())&&(studentName.equals(stu.getStudentName()))&&(studentId==stu.getStudentId())){
return true;
}else
return true;
}else{
return false;
}
}
}
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class test2 {
/**
* @param args
*/
public static void main(String[] args) {
Student2 stu1 = new Student2 (1,"zhangsan",28);
Student2 stu2 = new Student2 (2,"zhagnsan",19);
Student2 stu3 = new Student2 (3,"wangwu",19);
Student2 stu4 = new Student2 (4,"wangwu",19);
Student2 stu5 = new Student2 (5,"zhaoliu",18);
ArrayList<Student2> list = new ArrayList<Student2>();
list.add(stu1);
list.add(stu2);
list.add(stu3);
list.add(stu4);
list.add(stu5);
//这里就会自动根据规则进行排序
Collections.sort(list);
for(int i=0;i<list.size();i++){
Student2 stu=list.get(i);
System.out.println("年龄:"+stu.getAge()+" 姓名:"+stu.getStudentName()+" 学号:"+stu.getStudentId());
}
}
}
结果：
年龄:18
姓名:zhaoliu
学号:5
年龄:19
姓名:wangwu
学号:3
年龄:19
姓名:wangwu
学号:4
年龄:19
姓名:zhagnsan
学号:2
年龄:28 姓名:zhangsan
学号:1
注：大家可以看下api文档里对接口 Comparable<T>接口的介绍，里面说是建议重写equals方法，否则可能出现怪异的表现