1.遍历List并输出
List list = Arrays.asList(“apple”, “banana”, “orange”);
list.stream().forEach(System.out::println);
2.过滤List中的元素
List list = Arrays.asList(“apple”, “banana”, “orange”);
List filteredList = list.stream().filter(s -> s.startsWith(“a”)).collect(Collectors.toList());
3.对List中的元素进行排序
List list = Arrays.asList(“apple”, “banana”, “orange”);
List sortedList = list.stream().sorted().collect(Collectors.toList());
4.对List中的元素进行去重
List list = Arrays.asList(“apple”, “banana”, “orange”, “apple”, “banana”);
List distinctList = list.stream().distinct().collect(Collectors.toList());
5.对List中的元素进行分组
List list = Arrays.asList(“apple”, “banana”, “orange”, “avocado”, “apricot”);
Map<Integer, List> groupedMap = list.stream().collect(Collectors.groupingBy(String::length));
Map的例子
1.遍历Map并输出
Map<String, Integer> map = new HashMap<>();
map.put(“apple”, 1);
map.put(“banana”, 2);
map.put(“orange”, 3);
map.entrySet().stream().forEach(System.out::println);
2.获取Map中所有的key
Map<String, Integer> map = new HashMap<>();
map.put(“apple”, 1);
map.put(“banana”, 2);
map.put(“orange”, 3);
List keyList = map.entrySet().stream().map(Map.Entry::getKey).collect(Collectors.toList());
3.获取Map中所有的value
Map<String, Integer> map = new HashMap<>();
map.put(“apple”, 1);
map.put(“banana”, 2);
map.put(“orange”, 3);
List valueList = map.entrySet().stream().map(Map.Entry::getValue).collect(Collectors.toList());
4.过滤Map中的元素
Map<String, Integer> map = new HashMap<>();
map.put(“apple”, 1);
map.put(“banana”, 2);
map.put(“orange”, 3);
Map<String, Integer> filteredMap = map.entrySet().stream().filter(e -> e.getValue() > 1).collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
5.对Map中的元素进行排序
Map<String, Integer> map = new HashMap<>();
map.put(“apple”, 1);
map.put(“banana”, 2);
map.put(“orange”, 3);
Map<String, Integer> sortedMap = map.entrySet().stream().sorted(Map.Entry.comparingByValue()).collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new));