如何遍历Java中的json对象

Question

我正在尝试遍历json文件并获取所需的详细信息，这是我的json

{
"000": {
    "component": "c",
    "determinantType": "dt",
    "determinant": "d",
    "header": "h",
    "determinantvalue": "null"
},
"001": {
    "component": "t",
    "determinantType": "i",
    "determinant":"ld",
    "header": "D",
    "determinantvalue": "null"
},
"002": {
    "component": "x",
    "determinantType": "id",
    "determinant": "pld",
    "header": "P",
    "determinantValue": "null"
}}

我的java代码

FileReader file = new FileReader("test.json");
Object obj = parser.parse(file);
System.out.println(obj);
JSONObject jsonObject = (JSONObject) obj;            
JSONArray msg = (JSONArray) jsonObject.get(key);          
Iterator<String> iterator = msg.iterator();         
while (iterator.hasNext()) {
System.out.println(iterator.next());            
String component = (String) jsonObject.get("component");           
System.out.println("component: " + component);

如您在代码中所看到的，我正在导入json文件并尝试获取下一个元素并从中打印组件，我还应该同时打印标头，行列式和行列式值。谢谢

Answer 1

您没有数组-您拥有名称为“ 000”等的 属性 。数组如下所示：

"array": [ {
    "foo": "bar1",
    "baz": "qux1"
  }, {
    "foo": "bar2",
    "baz": "qux2"
  }
]

请注意，[ ... ]-表示JSON数组。

您可以遍历JSONObjectusing
的属性keys()：

// Unfortunately keys() just returns a raw Iterator...
Iterator keys = jsonObject.keys();
while (keys.hasNext()) {
    Object key = keys.next();
    JSONObject value = jsonObject.getJSONObject((String) key);
    String component = value.getString("component");
    System.out.println(component);
}

要么：

@SuppressWarnings("unchecked")
Iterator<String> keys = (Iterator<String>) jsonObject.keys();
while (keys.hasNext()) {
    String key = keys.next();
    JSONObject value = jsonObject.getJSONObject(key);
    String component = value.getString("component");
    System.out.println(component);
}