使用Stream api打印HashMap值

Question

HashMap<String, Double> missions = new HashMap<>();
missions.put("name", 1.0);
missions.put("name1", 2.0);
missions.keySet().stream().forEach(el-> System.out.println(el));

仅打印关键字

Answer 1

使用entrySet()（或values()，如果您需要的话）而不是keySet()：

Map<String, Double> missions = new HashMap<>();
missions.put("name", 1.0);
missions.put("name1", 2.0);
missions.entrySet().stream().forEach(e-> System.out.println(e));

Answer 2

HashMap<String, Double> missions = new HashMap<>();
missions.put("name", 1.0);
missions.put("name1", 2.0);
missions.entrySet().forEach(System.out::println);

输出：

name=1.0
name1=2.0

Answer 3

// Stores the values in a list which can later used

missions.values().stream().collect(Collectors.toList());

或

//print it to standard op

missions.values().forEach(val -> System.out.println(val));