android - 为什么这个 URL-JSON 解析代码在我提取标签时不起作用，但在我提取整个数组时有效？

Question

当我尝试解析整个数组时，它可以正常工作，但是当我尝试从 URL 中解析数组元素(如 ID、t、l 等)时，代码不起作用。

请详细说明，我是菜鸟:)

PS:我相信整个数据都是Strings形式的。喜欢:“l”:“219.20”。

网址如下: http://finance.google.com/finance/info?q=BSE:SBIN

其他资源如下:

MainActivity.java

public class MainActivity extends AppCompatActivity {

    public String theUrl;
    public String stockName;

    ListView lvStock;

    HttpURLConnection connection;
    URL url;
    InputStream inputStream;
    BufferedReader bufferedReader;
    StringBuffer stringBuffer;

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

        lvStock = (ListView) findViewById(R.id.lvStocks);

        stockName = "SBIN";
        theUrl = "http://finance.google.com/finance/info?q=BSE:" + stockName;
        Toast.makeText(MainActivity.this, "You have selected : " + stockName, Toast.LENGTH_SHORT).show();

    }

    public class RefreshStock extends AsyncTask<String, String, List<StockModel>> {

        @Override
        protected List<StockModel> doInBackground(String... params) {

            try {
                url = new URL(params[0]);

                connection = (HttpURLConnection) url.openConnection();
                connection.connect();

                inputStream = connection.getInputStream();

                bufferedReader = new BufferedReader(new InputStreamReader(inputStream));

                stringBuffer = new StringBuffer();

                String line = "";

                while ((line = bufferedReader.readLine()) != null)
                    stringBuffer.append(line + "\n");

                String data = stringBuffer.toString();

                return parseJSON(data);

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (connection != null)
                    connection.disconnect();
                try {
                    if (bufferedReader != null)
                        bufferedReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return null;
        }

        private List<StockModel> parseJSON(String json) {

            List<StockModel> stockModelList = new ArrayList<>();

            //Using it to remove the two forward slashes in the json online.
            json = json.substring(2);

            try {

                StockModel stockModel = new StockModel();
                JSONObject parentObject = new JSONObject();
                JSONArray jsonArray = parentObject.getJSONArray(json);

                    JSONObject childObject = jsonArray.getJSONObject(0);
                    String stockId = childObject.getString("id");
                    String stockName = childObject.getString("t");
                    String stockRate = childObject.getString("l");
                    String stockChange = childObject.getString("c");
                    String stockChangePercent = childObject.getString("cp");

                    stockModel.setId(stockId);
                    stockModel.setT(stockName);
                    stockModel.setL(stockRate);
                    stockModel.setC(stockChange);
                    stockModel.setCp(stockChangePercent);

                    stockModelList.add(stockModel);
                return stockModelList;
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return stockModelList;
        }

        protected void onPostExecute(List<StockModel> result) {
            super.onPostExecute(result);

            //Toast.makeText(getApplicationContext(), new StringBuilder().append("").append(result.toString()).toString(), Toast.LENGTH_LONG).show();
            StockAdapter adapter = new StockAdapter(getApplicationContext(), R.layout.listrow, result);
            lvStock.setAdapter(adapter);
        }
    }

    public class StockAdapter extends ArrayAdapter {

        private List<StockModel> stockModelList;
        private int resource;
        private LayoutInflater inflater;

        private StockAdapter(Context context, int resource, List<StockModel> objects) {
            super(context, resource, objects);

            stockModelList = objects;
            this.resource = resource;
            inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            ViewHolder holder = null;

            if (convertView == null) {

                holder = new ViewHolder();

                convertView = inflater.inflate(R.layout.listrow, null);

                holder.stockID = (TextView) convertView.findViewById(R.id.txtStockID);
                holder.stockName = (TextView) convertView.findViewById(R.id.txtStockName);
                holder.stockRate = (TextView) convertView.findViewById(R.id.txtStockRate);
                holder.stockChange = (TextView) convertView.findViewById(R.id.txtStockChange);
                holder.stockChangePercent = (TextView) convertView.findViewById(R.id.txtStockChangePercent);

                convertView.setTag(holder);
            } else {
                holder = (ViewHolder) convertView.getTag();
            }

            holder.stockID.setText(stockModelList.get(position).getId());
            holder.stockName.setText(stockModelList.get(position).getT());
            holder.stockRate.setText(stockModelList.get(position).getL());
            holder.stockChange.setText(stockModelList.get(position).getC());
            holder.stockChangePercent.setText(stockModelList.get(position).getCp());

            return convertView;
        }

    }

    private class ViewHolder {

        private TextView stockRate;
        private TextView stockChangePercent;
        private TextView stockChange;
        private TextView stockName;
        private TextView stockID;
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_refresh) {

            new RefreshStock().execute(theUrl);
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

}

另一个类如下:

package org.example.km.http2json.Models;

public class StockModel {

    private String id;
    private String t;
    //private String e;
    private String l;
    //private String l_fix;
    //private String l_cur;
    //private String s;
    //private String ltt;
    //private String lt;
    //private String llt_dts;
    private String c;
    //private String c_fix;
    private String cp;
    //private String cp_fix;
    //private String ccol;
    //private String pcls_fix;


    public String getId(){

        return id;
    }

    public void setId(String id){
        this.id = id;
    }

    public String getT(){

        return t;
    }

    public void setT(String t){
        this.t = t;
    }


    public String getL(){

        return l;
    }

    public void setL(String l){
        this.l = l;
    }


    public String getC(){

        return c;
    }

    public void setC(String c){
        this.c = c;
    }

    public String getCp(){

        return cp;
    }

    public void setCp(String cp){
        this.cp = cp;
    }


}
/*

// [
{
"id": "13564339"
,"t" : "SBIN"
,"e" : "NSE"
,"l" : "219.20"                             // Last Value
,"l_fix" : "219.20"
,"l_cur" : "Rs.219.20"
,"s": "0"
,"ltt":"3:56PM GMT+5:30"
,"lt" : "Jul 1, 3:56PM GMT+5:30"
,"lt_dts" : "2016-07-01T15:56:11Z"
,"c" : "+0.40"                              //Change
,"c_fix" : "0.40"
,"cp" : "0.18"                              //Change Percent
,"cp_fix" : "0.18"
,"ccol" : "chg"
,"pcls_fix" : "218.8"                       // Previous Closing
}
]

*/

Answer 1

 // there is no data your parsing.. please check
JSONArray jsonArray = parentObject.getJSONArray("");

            JSONObject childObject = jsonArray.getJSONObject(0);
            String stockId = childObject.getString("id");
            String stockName = childObject.getString("t");
            String stockRate = childObject.getString("l");
            String stockChange = childObject.getString("c");
            String stockChangePercent = childObject.getString("cp");

注意:下面的数据将抛出解析器异常，删除前两个斜杠字符

// [ { "id": "13564339" ,"t" : "SBIN" ,"e" : "NSE" ,"l" : "219.20" ,"l_fix" : "219.20" ,"l_cur" : "Rs.219.20" ,"s": "0" ,"ltt":"3:56PM GMT+5:30" ,"lt" : "Jul 1, 3:56PM GMT+5:30" ,"lt_dts" : "2016-07-01T15:56:11Z" ,"c" : "+0.40" ,"c_fix" : "0.40" ,"cp" : "0.18" ,"cp_fix" : "0.18" ,"ccol" : "chg" ,"pcls_fix" : "218.8" } ]