常用的Lambda操作

1、打印集合中的数据

List<String> list = Arrays.asList("zhangsan", "lisi", "wangwu");//打印集合内的数据for(String s : list){System.out.println(s);}list.forEach(System.out::println);

2、列表排序

List<String> list = Arrays.asList("zhangsan", "lisi", "wangwu");list.sort(new Comparator<String>() {@Overridepublic int compare(String o1, String o2) {return o1.compareTo(o2);}});list.sort((s1, s2) -> s1.compareTo(s2));

3、过滤列表

List<String> list = Arrays.asList("zhangsan", "lisi", "wangwu");List<String> list2 = list.stream().filter(s -> s.startsWith("z")).collect(Collectors.toList());

4、映射：获取列表中的每个元素的长度

List<String> list = Arrays.asList("zhangsan", "lisi", "wangwu");List<Integer>list3 = new ArrayList<>();for(String s : list){list3.add(s.length());}List<Integer>list4 = list.stream().map(s -> s.length()).collect(Collectors.toList());

5、对列表中的数据进行求和操作

List<Integer> list5 = Arrays.asList(1,2,3,4,5);Integer sum1 = 0;for(Integer i : list5){sum1 += i;}int sum2 = list5.stream().reduce(0, (a, b) -> a + b);

6、分组操作

List<String> list = Arrays.asList("zhangsan", "lisi", "wangwu");Map<Integer, List<String>> group = new HashMap<>();for(String s : list){if(!group.containsKey(s.length())){group.put(s.length(), new ArrayList<>());}group.get(s.length()).add(s);}Map<Integer, List<String>>group2 = list.stream().collect(Collectors.groupingBy(String::length));Map<Integer, List<String>>group3 = list.stream().collect(Collectors.groupingBy(s -> s.length()));

7、实现接口

MyInterFace myInterFace = new MyInterFace() {@Overridepublic void doSomeThing(String s) {System.out.println(s);}};MyInterFace myInterFace1 = s -> System.out.println(s);public interface MyInterFace{void doSomeThing(String s);}

8、创建线程

Thread thread = new Thread(new Runnable() {@Overridepublic void run() {System.out.println("hello world");}});thread.start();Thread thread1 = new Thread(() -> System.out.println("hello word"));thread1.start();

9、进行判空操作

String str = "hello word";if(str != null) str.toUpperCase(); Optional.ofNullable(str).map(String::toUpperCase).ifPresent(System.out::println);

10、流水线操作

List<String> list6 = new ArrayList<>();for(String s : list){if(s.startsWith("a")){list6.add(s.toUpperCase());}}Collections.sort(list6);List<String> list7 = list.stream().filter(s -> s.startsWith("a")).map(String::toUpperCase).sorted().collect(Collectors.toList());