示例1
复制代码 代码如下:
package com.yonyou.test;
import java.util.arraylist;
import java.util.collections;
import java.util.comparator;
import java.util.list;
public class test {
public static void main(string[] args) {
student zlj = new student("丁晓宇", 21);
student dxy = new student("赵四", 22);
student cjc = new student("张三", 11);
student lgc = new student("刘武", 19);
list<student> studentlist = new arraylist<student>();
studentlist.add(zlj);
studentlist.add(dxy);
studentlist.add(cjc);
studentlist.add(lgc);
system.out.println("按照年齡排序：");
collections.sort(studentlist, new sortbyage());
for (student student : studentlist) {
system.out.println(student.getname() + " / " + student.getage());
}
system.out.println(" ========= ");
system.out.println("按照姓名排序");
collections.sort(studentlist, new sortbyname());
for (student student : studentlist) {
system.out.println(student.getname() + " / " + student.getage());
}
}
}
class sortbyage implements comparator {
public int compare(object o1, object o2) {
student s1 = (student) o1;
student s2 = (student) o2;
if (s1.getage() > s2.getage())
return 1;
else if (s1.getage() == s2.getage()) {
return 0;
}
return -1;
}
}
class sortbyname implements comparator {
public int compare(object o1, object o2) {
student s1 = (student) o1;
student s2 = (student) o2;
if(s1.getname().compareto(s2.getname()) < 0)
return -1;
else if (s1.getname().compareto(s2.getname()) > 0) {
return 1;
}
return 0;
}
}
class student{
private int age;
private string name;
public int getage() {
return age;
}
public void setage(int age) {
this.age = age;
}
public string getname() {
return name;
}
public void setname(string name) {
this.name = name;
}
public student(string name,int age) {
this.age = age;
this.name = name;
}
}
示例2
常常遇到数组排序的问题.比如我有一个person类,它的实例对象存储在arraylist数组中,现在要把arraylist数组中 的person对象按照年龄排序.
其实这种情况经常遇到.
下面给出源代码:
1:person.java文 件:
复制代码 代码如下:
public class person{
string name;
int age;
public person(string name,int age){
this.name = name;
this.age = age;
}
public int getage() {
return age;
}
public void setage(int age) {
this.age = age;
}
public string getname() {
return name;
}
public void setname(string name) {
this.name = name;
}
}
2:mycomparator.java
复制代码 代码如下:
// 实现comparator接口,也就是定义排序规则,你几乎可以定义任何规则
package com.infoearth;
import java.util.*;
public class mycomparator implements comparator{
public int compare(object o1,object o2) {
person p1=(person)o1;
person p2=(person)o2;
if(p1.age<p2.age)
return 1;
else
return 0;
}
}
3:listsort.java
复制代码 代码如下:
package com.infoearth;
import java.util.arraylist;
import java.util.collections;
import java.util.comparator;
public class listsort {
public static void main(string[] args){
arraylist list = new arraylist();
list.add(new person("lcl",28));
list.add(new person("fx",23));
list.add(new person("wqx",29));
comparator comp = new mycomparator();
collections.sort(list,comp);
for(int i = 0;i<list.size();i++){
person p = (person)list.get(i);
system.out.println(p.getname());
}
}
}
当然，如果你的list包装的是基本类型或者string，则只要 collections.sort(list);即可
