Question

我有一个只有JSON解析器的旧代码，这在2.3及更低版本中运行良好。现在，我正在尝试添加Async逻辑，以便它也适用于Android 3.0及更高版本。

“货币转换器”是我的JSON解析器类。

这是JSON的代码片段

    private void currencySave() {
    // TODO Auto-generated method stub
    AsyncTaskExample asyncTask = new AsyncTaskExample();
    asyncTask.execute();
}

private class AsyncTaskExample extends AsyncTask<String, Void, String> {
    // private String Content;
    private ProgressDialog Dialog;
    String response = "";

    protected void onPreExecute() {
        Dialog = new ProgressDialog(MoneyLoginActivity.this);
        Dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
        Dialog.setMessage("Loading Convertors. Please Wait ...");
        Dialog.setCancelable(false);
        Dialog.show();
    }

    protected String doInBackground(String... urls) {
        try {

            CurrencyConvertor jParser = new CurrencyConvertor();
            JSONObject json = jParser.getJSONFromUrl(url);
            try {
                // Getting Array of Contacts
                // getting JSON string from URL
                JSONObject rates = json.getJSONObject(TAG_RATES);
                dUSD = rates.getString(TAG_USD);
                dINR = rates.getString(TAG_INR);
                dEURO = rates.getString(TAG_EUR);
                dGBP = rates.getString(TAG_GBP);
                response = "Success";

            } catch (JSONException e) {
                e.printStackTrace();
                response = "Failed";
            }

        } catch (Exception e) {
            response = "Failed";
        }
        return response;
    }

    protected void onPostExecute(String result) {
        Dialog.dismiss();
        Dialog = null;
        if (response.equalsIgnoreCase("Success")) {
            //do nothing

        } else {
            Toast.makeText(MoneyLoginActivity.this,
                    "Sorry Unable to retrive data. Please try again later",
                    Toast.LENGTH_LONG).show();
        }

    }

}

我得到空指针异常。这是日志

03-09 15：43：08.364：E / AndroidRuntime（1073）：引起： java.lang.NullPointerException 03-09 15：43：08.364： E / AndroidRuntime（1073）：at com.android.internal.os.LoggingPrintStream.println（LoggingPrintStream.java:298） 03-09 15：43：08.364：E / AndroidRuntime（1073）：at com.jasmasuri.moneysheet.MoneyLoginActivity.decidePage（MoneyLoginActivity.java:128）

我在这段代码中得到它

CurrencyConvertor jParser = new CurrencyConvertor();
            JSONObject json = jParser.getJSONFromUrl(url);

Android - 使用Async的JSON解析器

0 个答案: