java map嵌套遍历

如果嵌套的Map的层数比较少，可以使用多重循环来实现遍历。如果嵌套的层数比较多，可以使用递归来实现遍历。

以下是使用多重循环实现遍历的示例代码：

Map<String, Map<String, String>> map = new HashMap<>();
map.put("key1", new HashMap<>());
map.get("key1").put("subkey1", "value1");
map.get("key1").put("subkey2", "value2");
map.put("key2", new HashMap<>());
map.get("key2").put("subkey1", "value3");
map.get("key2").put("subkey2", "value4");

for (Map.Entry<String, Map<String, String>> entry : map.entrySet()) {
    String key = entry.getKey();
    Map<String, String> submap = entry.getValue();
    for (Map.Entry<String, String> subentry : submap.entrySet()) {
        String subkey = subentry.getKey();
        String value = subentry.getValue();
        System.out.println("key: " + key + ", subkey: " + subkey + ", value: " + value);
    }
}

以下是使用递归实现遍历的示例代码：

Map<String, Object> map = new HashMap<>();
map.put("key1", new HashMap<>());
((Map<String, Object>) map.get("key1")).put("subkey1", "value1");
((Map<String, Object>) map.get("key1")).put("subkey2", "value2");
map.put("key2", new HashMap<>());
((Map<String, Object>) map.get("key2")).put("subkey1", "value3");
((Map<String, Object>) map.get("key2")).put("subkey2", "value4");

public void traverse(Map<String, Object> map) {
    for (Map.Entry<String, Object> entry : map.entrySet()) {
        String key = entry.getKey();
        Object value = entry.getValue();
        if (value instanceof Map) {
            traverse((Map<String, Object>) value);
        } else {
            System.out.println("key: " + key + ", value: " + value);
        }
    }
}

traverse(map);