Java8从HashMap中提取非空值和非空值

HashMap<String, String> hashMap = new HashMap<>();
hashMap.put("key1", "value1");
hashMap.put("key2", null);
hashMap.put("key3", "value3");
hashMap.put("key4", null);

hashMap.entrySet().stream()
        .filter(entry -> entry.getValue() != null)
        .forEach(entry -> System.out.println(entry.getKey() + " - " + entry.getValue()));

key1 - value1
key3 - value3

Iterator<Map.Entry<String, String>> iterator = hashMap.entrySet().iterator();
while (iterator.hasNext()) {
    Map.Entry<String, String> entry = iterator.next();
    if (entry.getValue() != null) {
        System.out.println(entry.getKey() + " - " + entry.getValue());
    }
}

key1 - value1
key3 - value3