Java List中通过对象属性排序，可实现多条件排序

**Java List 中通过对象属性排序**

在 Java 中，List 是一个非常常用的集合类，它可以存储一组元素。然而，在实际开发中，我们经常需要对这些元素进行排序，而不是简单地使用 Collections.sort() 方法，因为我们可能需要根据多个条件来排序。

本文将介绍如何在 Java List 中通过对象属性排序，并实现多条件排序。

###1. 使用 Comparator 接口首先，我们可以使用 Comparator 接口来实现排序。Comparator 接口提供了一个 compare() 方法，用于比较两个元素的大小。

javaimport java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

class Person {
 private String name;
 private int age;

 public Person(String name, int age) {
 this.name = name;
 this.age = age;
 }

 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;
 }
}

public class Main {
 public static void main(String[] args) {
 List persons = new ArrayList<>();
 persons.add(new Person("John",25));
 persons.add(new Person("Alice",30));
 persons.add(new Person("Bob",20));

 // 使用 Comparator 接口实现排序 Collections.sort(persons, new Comparator() {
 @Override public int compare(Person p1, Person p2) {
 if (p1.getAge() > p2.getAge()) return -1;
 else if (p1.getAge() < p2.getAge()) return1;
 else return0;
 }
 });

 // 输出排序后的结果 for (Person person : persons) {
 System.out.println(person.getName() + " " + person.getAge());
 }
 }
}

javaimport java.util.ArrayList;
import java.util.Collections;
import java.util.List;

class Person {
 private String name;
 private int age;

 public Person(String name, int age) {
 this.name = name;
 this.age = age;
 }

 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;
 }
}

public class Main {
 public static void main(String[] args) {
 List persons = new ArrayList<>();
 persons.add(new Person("John",25));
 persons.add(new Person("Alice",30));
 persons.add(new Person("Bob",20));

 // 使用 Lambda 表达式实现排序 Collections.sort(persons, (p1, p2) -> Integer.compare(p1.getAge(), p2.getAge()));

 // 输出排序后的结果 for (Person person : persons) {
 System.out.println(person.getName() + " " + person.getAge());
 }
 }
}

javaimport java.util.ArrayList;
import java.util.Collections;
import java.util.List;

class Person {
 private String name;
 private int age;

 public Person(String name, int age) {
 this.name = name;
 this.age = age;
 }

 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;
 }
}

public class Main {
 public static void main(String[] args) {
 List persons = new ArrayList<>();
 persons.add(new Person("John",25));
 persons.add(new Person("Alice",30));
 persons.add(new Person("Bob",20));

 // 使用方法引用实现排序 Collections.sort(persons, (p1, p2) -> Integer.compare(p1.getAge(), p2.getAge()));

 // 输出排序后的结果 for (Person person : persons) {
 System.out.println(person.getName() + " " + person.getAge());
 }
 }
}

javaimport java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

class Person {
 private String name;
 private int age;
 private double height;

 public Person(String name, int age, double height) {
 this.name = name;
 this.age = age;
 this.height = height;
 }

 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;
 }

 public double getHeight() {
 return height;
 }

 public void setHeight(double height) {
 this.height = height;
 }
}

public class Main {
 public static void main(String[] args) {
 List persons = new ArrayList<>();
 persons.add(new Person("John",25,175.5));
 persons.add(new Person("Alice",30,165.2));
 persons.add(new Person("Bob",20,180.1));

 // 使用多条件排序 Collections.sort(persons, (p1, p2) -> {
 if (p1.getAge() > p2.getAge()) return -1;
 else if (p1.getAge() < p2.getAge()) return1;
 else {
 if (p1.getHeight() > p2.getHeight()) return -1;
 else if (p1.getHeight() < p2.getHeight()) return1;
 else return0;
 }
 });

 // 输出排序后的结果 for (Person person : persons) {
 System.out.println(person.getName() + " " + person.getAge() + " " + person.getHeight());
 }
 }
}