Java 8 Stream API :如何在Map中处理空值

Map<String, Integer> map = new HashMap<>();
map.put("key1", 1);
map.put("key2", null);
map.put("key3", 3);

Map<String, Integer> filteredMap = map.entrySet()
        .stream()
        .filter(entry -> entry.getValue() != null)
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

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

Map<String, String> processedMap = map.entrySet()
        .stream()
        .map(entry -> {
            if (entry.getValue() == null) {
                entry.setValue("default");
            }
            return entry;
        })
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

Map<String, Integer> map = new HashMap<>();
map.put("key1", 1);
map.put("key2", null);
map.put("key3", 3);

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