参考 

 Using entrySet()

public void iterateUsingEntrySet(Map<String, Integer> map) {
    for (Map.Entry<String, Integer> entry : map.entrySet()) {
        System.out.println(entry.getKey() + ":" + entry.getValue());
    }
}

    Iterator<Map.Entry<String, Integer>> iterator = map.entrySet().iterator();
    while (iterator.hasNext()) {
        Map.Entry<String, Integer> entry = iterator.next();
        System.out.println(entry.getKey() + ":" + entry.getValue());
    }

 Using keySet()

public void iterateUsingKeySetAndForeach(Map<String, Integer> map) {
    for (String key : map.keySet()) {
        System.out.println(key + ":" + map.get(key));
    }
}

Iterator<String> iterator = map.keySet().iterator();
   while (iterator.hasNext()) {
       String key = iterator.next();
       System.out.println(key + ":" + map.get(key));
}

 

 Using values()

public void iterateValues(Map<String, Integer> map) {
    for (Integer value : map.values()) {
        System.out.println(value);
    }
}

    Iterator<Integer> iterator = map.values().iterator();
    while (iterator.hasNext()) {
        Integer value = iterator.next();
        System.out.println("value :" + value);
    }

Using forEach() and Lambda

  map.forEach((k, v) -> System.out.println((k + ":" + v)));

map.keySet().foreach(k -> System.out.println((k + ":" + map.get(k))));

map.values().forEach(v -> System.out.println(("value: " + v)));

Using Stream API

    map.entrySet().stream()
      // ... some other Stream processings
      .forEach(e -> System.out.println(e.getKey() + ":" + e.getValue()));