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java教程之二個arraylist排序的示例分享

更新時間：2014年03月07日 14:07:53 作者：

常常遇到數(shù)組排序的問題，下面提供二個java的arraylist排序示例,需要的朋友可以參考下

示例1

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("丁曉宇", 21);
  Student dxy = new Student("趙四", 22);
  Student cjc = new Student("張三", 11);
  Student lgc = new Student("劉武", 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

常常遇到數(shù)組排序的問題.比如我有一個Person類,它的實(shí)例對象存儲在ArrayList數(shù)組中,現(xiàn)在要把ArrayList數(shù)組中的Person對象按照年齡排序.
其實(shí)這種情況經(jīng)常遇到.
下面給出源代碼:

1:Person.java文件:

復(fù)制代碼代碼如下:

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

復(fù)制代碼代碼如下:

// 實(shí)現(xiàn)Comparator接口,也就是定義排序規(guī)則,你幾乎可以定義任何規(guī)則
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

復(fù)制代碼代碼如下:

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());
         }

     }

}

當(dāng)然，如果你的List包裝的是基本類型或者String，則只要 Collections.sort(list);即可

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