在JSON解析时如何检查元素是否存在?

时间:2016-12-28 20:28:38

标签: java json org.json

我有以下json字符串。有时,有多个定义元素,有时只有一个。我是JSON解析的新手,我以某种非常原始的方式设法获得第一个定义元素的值。但是,我无法获得所有定义值,因为我没有可以在线找到的资源。我是否必须检查是否存在第二次出现或有更好的方法吗?

JSON:

ID  CN
1   PHLSERVER01
1   NYCSFAX01
1   KONGRDATA01
1   LAXSERVER01

获取定义值的Java代码段:

{
  "metadata": {
    "provider": "Oxford University Press"
  },
  "results": [
    {
      "id": "edifice",
      "language": "en",
      "lexicalEntries": [
        {
          "entries": [
            {
              "etymologies": [
                "late Middle English: via Old French from Latin aedificium, from aedis dwelling + facere make"
              ],
              "grammaticalFeatures": [
                {
                  "text": "Singular",
                  "type": "Number"
                }
              ],
              "senses": [
                {
                  "definitions": [
                    "a large, imposing building."
                  ],
                  "id": "m_en_gb0256160.001",
                  "registers": [
                    "formal"
                  ]
                },
                {
                  "definitions": [
                    "a complex system of beliefs:"
                  ],
                  "examples": [
                    {
                      "text": "the concepts on which the edifice of capitalism was built"
                    }
                  ],
                  "id": "m_en_gb0256160.002",
                  "registers": [
                    "formal"
                  ]
                }
              ]
            }
          ],
          "language": "en",
          "lexicalCategory": "Noun",
          "pronunciations": [
            {
              "audioFile": "http://audio.oxforddictionaries.com/en/mp3/edifice_gb_1.mp3",
              "dialects": [
                "British English"
              ],
              "phoneticNotation": "IPA",
              "phoneticSpelling": "ˈɛdɪfɪs"
            }
          ],
          "text": "edifice"
        }
      ],
      "type": "headword",
      "word": "edifice"
    }
  ]
}

1 个答案:

答案 0 :(得分:1)

一切看起来都不错,但你应该停在getJSONArray(“感官”)。

应该是

JSONArray senses= .....getJSONArray("senses");

然后你应该循环通过该数组的元素。这样的事情。

ArrayList<String> definitions = new ArrayList<String>();
for(int i =0; i < senses.length(); i++){
    definitions.add(senses.getJSONObject(i).optString("definitions","");
}

但在此之前你应该注意到你的定义json没有很好地形成它应该像

"definitions":"blablabl blablab"

因为它不是数组;。