java8 lambda集合排序

java8 lambda集合排序 1.对实体对象排序

使用Comparator.comparing按照动物年龄升序/降序排序

public class Demo {
    public static void main(String[] args) {

        ArrayList listAnimals = new ArrayList<>();
        listAnimals.add(new Animal().setName("狗").setAge(2));
        listAnimals.add(new Animal().setName("猫").setAge(3));
        listAnimals.add(new Animal().setName("老鼠").setAge(1));
        listAnimals.sort(Comparator.comparing(Animal::getAge));
        listAnimals.forEach(System.out::println);
//        降序排序
//        listAnimals.sort(Comparator.comparing(Animal::getAge).reversed());
    }
}

2. 对数字排序

public class Demo {
    public static void main(String[] args) {

        List listIntegers = Arrays.asList(3, 1, 2);
        listIntegers.sort((k, v) -> k.compareTo(v.intValue()));
        listIntegers.forEach(System.out::println);
        // 降序排序
        // listIntegers.sort((k,v)->v.compareTo(k.intValue()));
        // listIntegers.forEach(System.out::println);
    }
}

3. 对字符串排序

public class Demo {
    public static void main(String[] args) {

        List listStrings = Arrays.asList("abandon","dog","cat","banana");
        listStrings.sort(String::compareTo);
        System.out.println(listStrings); // 控制台打印 [abandon, banana, cat, dog]
        // 降序排序
        Collections.reverse(listStrings);
        System.out.println(listStrings); // 控制台打印 [dog, cat, banana, abandon]
    }
}