Java8 用Lambda表达式给List集合排序的实现

Java8 用Lambda表达式给List集合排序的实现

Lambda用到了JDK8自带的一个函数式接口Comparator。

准备一个Apple类

pubhttp://lic 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 {

@Override

public int compare(Apple o1, Apple o2) {

return o1.getWeight() - o2.getWeight();

}

}

步骤二：准备一个List集合

ArrayList 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() {

@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 comparing = comparing((Apple a) -> a.getWeight());

inventory.sort(comparinhttp://g((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》

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。