我想使用数组列出 JSON 字符串中的数据，但为啥我的应用程序崩溃了？

Posted 2023-04-19

【中文标题】我想使用数组列出 JSON 字符串中的数据，但为啥我的应用程序崩溃了？

【英文标题】：I want to list data from JSON string using an array, but why my app crashes?我想使用数组列出 JSON 字符串中的数据，但为什么我的应用程序崩溃了？

【发布时间】：2020-03-08 15:35:20

【问题描述】：

我想在 ListView 中列出来自 JSON 字符串的数据。 我将字符串存储在一个数组中。 当我在JSONObject day = jsonArray.getJSONObject(0); 行中写i 时，应用程序崩溃了。

我做错了什么？

String json_string1 = "\"list\":[\"dt\":1471255200,\"temp\":\"day\":30.04,\"min\":17.35,\"max\":30.04,\"pressure\":1018.83,\"humidity\":35,\"weather\":[\"id\":802,\"main\":\"Clouds\",\"de scription\":\"scattered clouds\",\"icon\":\"03d\"],\"speed\":2.66,\"deg\":314,\"clouds\":48,\"dt\":1471341600,\"temp\":\"day\":29.48,\"min\":19.3,\"max\":29.95,\"pressure\":1018.63,\"humidity\":100,\"weather\":[\"id\":501,\"main\":\"Rain\",\"des cription\":\"moderate rain\",\"icon\":\"10d\"],\"speed\":2.46,\"deg\":28,\"clouds\":92,\"rain\":8.5,\"dt\":1471428000,\"temp\":\"day\":28.96,\"min\":17.84,\"m ax\":297.54,\"pressure\":1012.1,\"humidity\":95,\"weather\":[\"id\":501,\"main\":\"Ra in\",\"description\":\"moderate rain\",\"icon\":\"10d\"],\"speed\":2.27,\"deg\":118,\"clouds\":88,\"rain\":5.55,\"dt\":1471514400,\"temp\":\"day\":26.89,\"min\":17.84,\" max\":28.95,\"pressure\":1014.27,\"humidity\":83,\"weather\":[\"id\":500,\"main\":\"R ain\",\"description\":\"light rain\",\"icon\":\"10d\"],\"speed\":1.98,\"deg\":93,\"clouds\":20,\"dt\":1471600800,\"temp\":\"day\":30.04,\"min\":21.87,\"max\":30.04,\"pressure\":1014.65,\"humidity\":0,\"weather\":[\"id\":500,\"main\":\"Rain\",\"descrip tion\":\"light rain\",\"icon\":\"10d\"],\"speed\":1.66,\"deg\":194,\"clouds\":11,\"rain\":0.22,\"dt\":1471687200,\"temp\":\"day\":31.3,\"min\":22.56,\"max\":32.3,\"p ressure\":1018.6,\"humidity\":0,\"weather\":[\"id\":500,\"main\":\"Rain\",\"descriptio n\":\"light rain\",\"icon\":\"10d\"],\"speed\":1.69,\"deg\":180,\"clouds\":16,\"rain\":0.77,\"dt\":1471773600,\"temp\":\"day\":31.77,\"min\":21.67,\"max\":30.77,\"pressure\":1016.93,\"humidity\":0,\"weather\":[\"id\":500,\"main\":\"Rain\",\"description\":\"light rain\",\"icon\":\"10d\"],\"speed\":2.49,\"deg\":227,\"clouds\":14,\"rain\":2.2]";

JSONObject jsonObject;

String[] days_array = new String[7];

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    try 
        jsonObject = new JSONObject(json_string1);
        JSONArray jsonArray = jsonObject.optJSONArray("list");
        int lengthJsonArr = jsonArray.length();

        for (int i = 0; i < lengthJsonArr; i++) 

            JSONObject day = jsonArray.getJSONObject(0);

            JSONObject temp = day.getJSONObject("temp");
            int min = temp.getInt("min");
            int max = temp.getInt("max");

            JSONArray weather = day.getJSONArray("weather");

            JSONObject zero = weather.getJSONObject(0);
            String main = zero.getString("main");

            double speed = day.getDouble("speed");

            days_array[i] = max + "/" + min + ", " + main + ", Wind=" + speed;
        
     catch (JSONException e) 
        e.printStackTrace();
    

    ListView ListView = (ListView) findViewById(R.id.list_view);

    ArrayAdapter adapter = new ArrayAdapter<String>(this, R.layout.list_layout, R.id.item_name, days_array);

    ListView.setAdapter(adapter);

【参考方案1】：

您有两个错误的属性名称："m ax" 和 " max"。这个固定的 json 可以工作：

String json_string1 = "\"list\":[\"dt\":1471255200,\"temp\":\"day\":30.04,\"min\":17.35,\"max\":30.04,\"pressure\":1018.83,\"humidity\":35,\"weather\":[\"id\":802,\"main\":\"Clouds\",\"de scription\":\"scattered clouds\",\"icon\":\"03d\"],\"speed\":2.66,\"deg\":314,\"clouds\":48,\"dt\":1471341600,\"temp\":\"day\":29.48,\"min\":19.3,\"max\":29.95,\"pressure\":1018.63,\"humidity\":100,\"weather\":[\"id\":501,\"main\":\"Rain\",\"des cription\":\"moderate rain\",\"icon\":\"10d\"],\"speed\":2.46,\"deg\":28,\"clouds\":92,\"rain\":8.5,\"dt\":1471428000,\"temp\":\"day\":28.96,\"min\":17.84,\"max\":297.54,\"pressure\":1012.1,\"humidity\":95,\"weather\":[\"id\":501,\"main\":\"Ra in\",\"description\":\"moderate rain\",\"icon\":\"10d\"],\"speed\":2.27,\"deg\":118,\"clouds\":88,\"rain\":5.55,\"dt\":1471514400,\"temp\":\"day\":26.89,\"min\":17.84,\"max\":28.95,\"pressure\":1014.27,\"humidity\":83,\"weather\":[\"id\":500,\"main\":\"R ain\",\"description\":\"light rain\",\"icon\":\"10d\"],\"speed\":1.98,\"deg\":93,\"clouds\":20,\"dt\":1471600800,\"temp\":\"day\":30.04,\"min\":21.87,\"max\":30.04,\"pressure\":1014.65,\"humidity\":0,\"weather\":[\"id\":500,\"main\":\"Rain\",\"descrip tion\":\"light rain\",\"icon\":\"10d\"],\"speed\":1.66,\"deg\":194,\"clouds\":11,\"rain\":0.22,\"dt\":1471687200,\"temp\":\"day\":31.3,\"min\":22.56,\"max\":32.3,\"p ressure\":1018.6,\"humidity\":0,\"weather\":[\"id\":500,\"main\":\"Rain\",\"descriptio n\":\"light rain\",\"icon\":\"10d\"],\"speed\":1.69,\"deg\":180,\"clouds\":16,\"rain\":0.77,\"dt\":1471773600,\"temp\":\"day\":31.77,\"min\":21.67,\"max\":30.77,\"pressure\":1016.93,\"humidity\":0,\"weather\":[\"id\":500,\"main\":\"Rain\",\"description\":\"light rain\",\"icon\":\"10d\"],\"speed\":2.49,\"deg\":227,\"clouds\":14,\"rain\":2.2]";

为确保不再发生这种情况，您可以使用在线工具（例如下一个https://jsoneditoronline.org/）来验证您未来的 json，然后再认为您的代码有任何错误。

还有一件事，您还可以通过String jsonString1 改进变量String json_string1 的名称以保持java 的驼峰式大小写约定