rxjava2代码实战5--distinct,filter,buffer

向右看齐 2022-06-03 02:54 185阅读 0赞

distinct: 对数据源里的数据去重后输出  
filter:根据过滤规则过滤数据  
buffer:隔m个数取n个数

代码地址：

GitHub - GodisGod/Rxjava2Test
    https://github.com/GodisGod/Rxjava2Test

### distinct: ###

我们这里有一个数据源：  
private Integer\[\] datas = \{1, 1, 1, 2, 2, 2, 3, 3, 4, 4, 5, 5\};

#### 注意这里是Integer对象数组,如果是int\[\]是不行的哦，大家可以试一下 ####

我们对这些数字去重后输出

Observable.fromArray(datas)//注意这里是Integer数组,如果是int[]是不行的哦，大家可以试一下
                                    .distinct()
                                    .subscribe(new Consumer<Integer>() {
                                        @Override
                                        public void accept(Integer value) throws Exception {
                                            Log.i("LHD", "distinct : " + value);
                                            tvResult.append(value + " ");
                                        }
                                    });

结果：  
![distinct][]

再试一下把一个对象list过滤重复数据，这里需要我们自己定义一下根据对象的哪个字段来过滤，如果两个对象这个字段相等就过滤

我们定义了一个学生数据源：

Student student1 = new Student("LHD", 90);
            Student student2 = new Student("LHD1", 80);
            Student student3 = new Student("LHD2", 70);
            Student student4 = new Student("LHD3", 96);
            Student student2 = new Student("LHD4", 80);
            Student student22 = new Student("LHD4", 80);
            Student student23 = new Student("LHD4", 80);
            Student student3 = new Student("LHD5", 70);
            Student student4 = new Student("LHD5", 70);

Observable.fromIterable(students)
                            .distinct(new Function<Student, String>() {
                                @Override
                                public String apply(Student student) throws Exception {
                                    return student.getName();//如果两个学生分数一样就过滤
                                }
                            })
                            .subscribe(new Consumer<Student>() {
                                @Override
                                public void accept(Student student) throws Exception {
                                    Log.i("LHD", "distinct : " + student.getName());
                                    tvResult.append(student.getName() + " ");
                                }
                            });

输出结果：

![distinct][distinct 1]

### filter:使用很简单，大家看代码就会啦(\#^.^\#) ###

Observable.fromIterable(students)
                            .filter(new Predicate<Student>() {
                                @Override
                                public boolean test(Student student) throws Exception {
                                    return student.getScore() > 80;//大于80分的过滤
                                }
                            }).subscribe(new Consumer<Student>() {
                        @Override
                        public void accept(Student student) throws Exception {
                            Log.i("LHD", " filter: " + student.getName());
                            tvResult.append("大于80分的:\n" + student.getName() + "\n");
                        }
                    });

输出结果：

![filter][]

### buffer:每隔m个数据输出n个数据 ###

数据源：每三个里面输出前两个，如下图所示

Student student1 = new Student("LHD", 90);//-----------输出
            Student student2 = new Student("LHD1", 80);//-----------输出
            Student student3 = new Student("LHD2", 70);
    
            Student student4 = new Student("LHD3", 96);//-----------输出
            Student student2 = new Student("LHD4", 80);//-----------输出
            Student student22 = new Student("LHD4", 80);
    
            Student student23 = new Student("LHD4", 80);//-----------输出
            Student student3 = new Student("LHD5", 70);//-----------输出
            Student student4 = new Student("LHD5", 70);

Observable.fromIterable(students)
                            .buffer(2, 3)//先取2个,每三个再取2个
                            .subscribe(new Consumer<List<Student>>() {
                                @Override
                                public void accept(List<Student> students) throws Exception {
                                    for (Student s : students) {
                                        Log.i("LHD", " buffer: " + s.getName());
                                        tvResult.append(s.getName() + " " + s.getScore() + "\n");
                                    }
    
                                }
                            });

输出结果：

![buffer][]

[distinct]: /images/20220603/488f1342bac54102a1af32d6ea4a46c4.png
[distinct 1]: /images/20220603/cfe92f06a4bb4a3b81229c9286d2504b.png
[filter]: /images/20220603/52c6d746df3841f1b1307a98449c74e0.png
[buffer]: /images/20220603/4f67bb1c14524fce8daca0332808e549.png