Lambda Expressions(Sort)

最新推荐文章于 2021-09-03 11:29:14 发布

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本文介绍如何使用Lambda表达式简化Java中对象数组的排序过程。通过不同的Lambda表达式实现，包括直接比较年龄、按年龄和姓名多重排序以及自定义比较器等，展示了Lambda表达式的灵活性与强大功能。

Lambda Expressions

Use lambda expression to implement sort directly,no need to use new function.

    @Test(dataProvider = "persons")
    public void testSortPersons4(Person[] persons) {
        List<Person> personCollection = Arrays.asList(persons);
        personCollection.sort(Comparator.comparing((person) -> person.getAge()));
        assertSortedPersons(personCollection.toArray(persons));
    }

    @Test(dataProvider = "persons")
    public void testSortPersons5(Person[] persons) {
        List<Person> personCollection = Arrays.asList(persons);
        personCollection.sort(Comparator.comparing(Person::getAge));
        assertSortedPersons(personCollection.toArray(persons));
    }

    @Test(dataProvider = "persons")
    public void testSortPersons6(Person[] persons) {
        List<Person> personCollection = Arrays.asList(persons);
        personCollection.sort(Comparator.comparing(Person::getAge).thenComparing(Person::getName));
        assertSortedPersons(personCollection.toArray(persons));
    }

Use multi sort condition

    @Test(dataProvider = "persons")
    public void testSortPersons7(Person[] persons) {
        List<Person> personCollection = Arrays.asList(persons);
        personCollection
                .sort(Comparator.comparing(Person::getAge).reversed().reversed().thenComparing(Person::getName));
        assertSortedPersons(personCollection.toArray(persons));
    }

    @Test(dataProvider = "persons")
    public void testSortPersons8(Person[] persons) {
        List<Person> personCollection = Arrays.asList(persons);
        personCollection.sort((person1, person2) -> {
            int ageCompare = person1.getAge() - person2.getAge();
            return ageCompare != 0 ? ageCompare : person1.getName().compareTo(person2.getName());
        });
        assertSortedPersons(personCollection.toArray(persons));
    }