本篇文章為大家展示了List集合中的對象如何實現按屬性大小排序，內容簡明扼要并且容易理解，絕對能使你眼前一亮，通過這篇文章的詳細介紹希望你能有所收獲。
實例如下：
package com.huad.luck;
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) {
Person p = new Person();
p.setName("tom");
p.setAge(11);
Person p1 = new Person();
p1.setName("lilei");
p1.setAge(19);
Person p2 = new Person();
p2.setName("json");
p2.setAge(15);
List<Person> list =new ArrayList<Person>();
list.add(p);
list.add(p1);
list.add(p2);
Collections.sort(list,new Comparator<Person>() {
//這里可以再Person中實現 Comparator<T>接口，重寫compare方法
@Override
public int compare(Person o1, Person o2) {
//這里按照名字排序
return o1.getName().compareTo(o2.getName());
//這里按照age排序
//return (o1.getAge()+"").compareTo(o2.getAge()+"");
//。。。根據不同屬性值排序
}
});
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i).getName());
}
}
}
//Person類
package com.huad.luck;
public class Person{
private String name ;
private int age;
public Person(String name , int age) {
this.name = name;
this.age = age;
}
public Person( ) {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
<p ><span >用collection.sort（）方法對list集合排序</span><br /></p><p ><span ><span ></span></span></p><p >第一種是list中的對象實現Comparable接口，如下：<span > </span></p><pre class="java" >/**
* 根據order對User排序
*/
public class User implements Comparable<User>{
private String name;
private Integer order;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getOrder() {
return order;
}
public void setOrder(Integer order) {
this.order = order;
}
public int compareTo(User arg0) {
return this.getOrder().compareTo(arg0.getOrder());
}
}測試一下：
public class Test{
public static void main(String[] args) {
User user1 = new User();
user1.setName("a");
user1.setOrder(1);
User user2 = new User();
user2.setName("b");
user2.setOrder(2);
List<User> list = new ArrayList<User>();
//此處add user2再add user1
list.add(user2);
list.add(user1);
Collections.sort(list);
for(User u : list){
System.out.println(u.getName());
}
}
}輸出結果如下
a
b
第二種方法是根據Collections.sort重載方法來實現，例如：
/**
* 根據order對User排序
*/
public class User { //此處無需實現Comparable接口
private String name;
private Integer order;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getOrder() {
return order;
}
public void setOrder(Integer order) {
this.order = order;
}
}主類中這樣寫即可：
public class Test{
public static void main(String[] args) {
User user1 = new User();
user1.setName("a");
user1.setOrder(1);
User user2 = new User();
user2.setName("b");
user2.setOrder(2);
List<User> list = new ArrayList<User>();
list.add(user2);
list.add(user1);
Collections.sort(list,new Comparator<User>(){
public int compare(User arg0, User arg1) {
return arg0.getOrder().compareTo(arg1.getOrder());
}
});
for(User u : list){
System.out.println(u.getName());
}
}
}輸出結果如下
a
b
前者代碼結構簡單，但是只能根據固定的屬性排序，后者靈活，可以臨時指定排序項，但是代碼不夠簡潔
多字段的場合：
Collections.sort(list,new Comparator<User>(){
public int compare(User arg0, User arg1) {
// 第一次比較專業
int i = arg0.getOrder().compareTo(arg1.getOrder());
// 如果專業相同則進行第二次比較
if(i==0){
// 第二次比較
int j=arg0.getXXX().compareTo(arg1.getXXX());
// 如果學制相同則返回按年齡排序
if(j==0){
return arg0.getCCC().compareTo(arg1.getCCC());
}
return j;
}
return i;
}
});以下是另外一個例子
package test;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class ArrayListTest {
public static void main(String[] args) {
ArrayList<Exmployee> arrayList = new ArrayList<Exmployee>() ;
arrayList.add(new Exmployee("zengqiang",new Integer(5000))) ;
arrayList.add(new Exmployee("zengmin",new Integer(4000))) ;
arrayList.add(new Exmployee("liuxiaojuan",new Integer(4200))) ;
arrayList.add(new Exmployee("giuming",new Integer(2200))) ;
Collections.sort(arrayList, new Comparator<Exmployee>(){
public int compare(Exmployee arg0, Exmployee arg1) {
return arg1.getSalary()-arg0.getSalary() ; //按照工資升序
//return arg0.getSalary()-arg1.getSalary() ; 按照工資降序
//return arg0.getName().compareTo(arg1.getName()) ; 按照姓名升序
}
});
for(Exmployee e:arrayList)
System.out.println(e.getName()+"'s salary is "+e.getSalary()) ;
}
}
class Exmployee {
public Exmployee(String name, int salary) {
this.name = name ;
this.salary = salary ;
}
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getSalary() {
return salary;
}
public void setSalary(int salary) {
this.salary = salary;
}
private int salary;
}上述內容就是List集合中的對象如何實現按屬性大小排序，你們學到知識或技能了嗎？如果還想學到更多技能或者豐富自己的知識儲備，歡迎關注億速云行業資訊頻道。
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