Java8 Comparator 排序方法

Java8 中 Comparator 接口提供了一些静态方法，可以方便于我们进行排序操作，下面通过例子讲解下如何使用

对整数列表排序(升序)

List list = Arrays.asList(1, 4, 2, 6, 2, 8);

list.sort(Comparator.naturalOrder());

System.out.println(list);

对整数列表排序(降序)

List list = Arrays.asList(1, 4, 2, 6, 2, 8);

list.sort(Comparator.reverseOrder());

System.out.println(list);

根据对象属性(年龄)进行排序

public class Test {

public static void main(String[] args) {

List personList = new ArrayList<>();

personList.add(new Person("a", 2));

personList.add(new Person("b", 4));

personList.add(new Person("c", 7));

// 升序

personList.sort(Comparator.comparingInt(Person::getAge));

// 降序

personList.sort(Comparator.comparingInt(Person::getAge).reversed());

System.out.println(personList);

}

public static class Person {

private String name;

private Integer age;

public Person(String name, Integer age) {

this.name = name;

this.age = age;

}

public Integer getAge() {

return age;

}

// ... toString 方法

}

}

根据对象属性(价格、速度)进行排序，需要注意的是，排序有先后之分，不同的顺序会导致不同的结果

public class Test {

public static void main(String[] args) {

List list = new ArrayList<>();

list.add(new Computer("xiaomi",4000,6));

list.add(new Computer("sony",5000,4));

list.add(new Computer("dell",4000,5));

list.add(new Computer("mac",6000,8));

list.add(new Computer("micro",5000,6));

// 先以价格(升序)、后再速度(升序)

list.sort(Comparator.comparingInt(Computer::getPrice).thenComparingInt(Computer::getSpeed));

// 先以速度(降序)、后再价格(升序)

list.sort(Comparator.comparingInt(Computer::getSpeed).reversed().thenComparingInt(Computer::getPrice));

// 先以价格(降序)、后再速度(降序)

list.sort(Comparator.comparingInt(Computer::getPrice).thenComparingInt(Computer::getSpeed).reversed());

System.out.println(list);

}

public static class Computer {

private String name;

private Integer price;

private Integer speed;

public Computer(String name, Integer price, Integer speed) {

this.name = name;

this.price = price;

this.speed = speed;

}

public Integer getPrice() {

return price;

}

public void setPrice(Integer price) {

this.price = price;

}

public Integer getSpeed() {

return speed;

}

public void setSpeed(Integer speed) {

this.speed = speed;

}

// ... toString 方法

}

}