Java版Lambda表达式，开发效率直线飙升！

曾经终败给现在 2024-04-26 04:43 5阅读 0赞

### Java版Lambda表达式，开发效率直线飙升！ ###

//集合变量
    List<String> lines= Arrays.asList("Apple","BananA","Pear","Car","Bird","DOG","egg","chicKEN");

### 1. 遍历输出 ###

list.forEach(System.out::println);

输出结果

Apple
    tiger
    Lion
    BananA
    Pear
    Car
    Bird
    DOG
    egg
    chicKEN

### 2. 全部小写输出 ###

List<String> lowerList = list.stream().map(String::toLowerCase).collect(Collectors.toList());

输出结果

[apple, tiger, lion, banana, pear, car, bird, dog, egg, chicken]

### 3. 全部大写输出 ###

List<String> upperList = list.stream().map(String::toUpperCase).collect(Collectors.toList());

输出结果

[APPLE, TIGER, LION, BANANA, PEAR, CAR, BIRD, DOG, EGG, CHICKEN]

### 4. 数组升序输出 ###

List<String> sortList = list.stream().map(String::toLowerCase)
      							.sorted(String::compareToIgnoreCase).collect(Collectors.toList());

输出结果

[apple, banana, bird, car, chicken, dog, egg, lion, pear, tiger]

### 5. 数组降序输出 ###

List<String> oderList = list.stream().map(String::toLowerCase)
    						.sorted((a,b)->b.compareToIgnoreCase(a)).collect(Collectors.toList());

输出结果

[tiger, pear, lion, egg, dog, chicken, car, bird, banana, apple]

### 6. 过滤含a字母的变量输出 ###

List<String> filterList = list.stream().filter(s->s.contains("a")).collect(Collectors.toList());

输出结果

[BananA, Pear, Car]

### 7.输出各变量的字段长度 ###

List<Integer> lenList = list.stream().map(String::length).collect(Collectors.toList());

输出结果

[5, 5, 4, 6, 4, 3, 4, 3, 3, 7]

### 8. 按照字段长度分组 ###

Map<Integer, List<String>> groupList = list.stream().collect(Collectors.groupingBy(String::length));

输出结果

{
        
    	3=[Car, DOG, egg], 
    	4=[Lion, Pear, Bird], 
    	5=[Apple, tiger], 
    	6=[BananA], 
    	7=[chicKEN]
    }

### 9.获取数组的总字段长度 ###

Integer reduce = list.stream().map(String::length).reduce(0, Integer::sum);

输出结果

### 9.分页输出集合 ###

//1、当前页
            int pageNum = 1;
            //2、每页条数
            int pageSize = 3;
            //3、总条数
            int totalNum = list.size();
            //4、总页数
            int totalPage = totalNum % pageSize == 0 ? totalNum / pageSize : totalNum / pageSize + 1;
            for (int i = 1; i <= totalPage; i++) {
        
                pageNum = i <= 1 ? 0 : (i - 1) * pageSize;
                List<String> collect = list.stream().skip(pageNum).limit(pageSize).collect(Collectors.toList());
                System.out.println("第" + i + "页数据：" + collect);
            }

输出结果

第1页数据：[Apple, tiger, Lion]
    第2页数据：[BananA, Pear, Car]
    第3页数据：[Bird, DOG, egg]
    第4页数据：[chicKEN]