Lambda用到了JDK8自带的一个函数式接口Comparator<T>。
准备一个Apple类
public class Apple {
private int weight;
private String color;
public Apple(){}
public Apple(int weight) {
this.weight = weight;
}
public Apple(int weight, String color) {
this.weight = weight;
this.color = color;
}
setters();getters();toString();
}
步骤一：
public class AppleComparator implements Comparator<Apple> {
@Override
public int compare(Apple o1, Apple o2) {
return o1.getWeight() - o2.getWeight();
}
}
步骤二：准备一个List集合
ArrayList<Apple> inventory = Lists.newArrayList(
new Apple(10, "red"),
new Apple(5, "red"),
new Apple(1, "green"),
new Apple(15, "green"),
new Apple(2, "red"));
步骤三：顺序排序，三种方式
/**
* 顺序排序
*/
// 1、传递代码，函数式编程
inventory.sort(new AppleComparator());
System.out.println(inventory);
// 2、匿名内部类
inventory.sort(new Comparator<Apple>() {
@Override
public int compare(Apple o1, Apple o2) {
return o1.getWeight() - o2.getWeight();
}
});
// 3、使用Lambda表达式
inventory.sort((a, b) -> a.getWeight() - b.getWeight());
// 4、使用Comparator的comparing
Comparator<Apple> comparing = comparing((Apple a) -> a.getWeight());
inventory.sort(comparing((Apple a) -> a.getWeight()));
//或者等价于
inventory.sort(comparing(Apple::getWeight));
步骤四：逆序排序
/** * 逆序排序 */ // 1、 根据重量逆序排序 inventory.sort(comparing(Apple::getWeight).reversed());
步骤五：如果两个苹果一样重，就得再找一个条件来进行排序
// 2、如果两个苹果的重量一样重，怎么办？那就再找一个条件进行排序呗 inventory.sort(comparing(Apple::getWeight).reversed().thenComparing(Apple::getColor));
https://gitee.com/play-happy/base-project
参考：
【1】《Java8实战》
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。
