Question

我正在关注使用PHP脚本和JSON将Android应用程序连接到MYSQL的教程从这个链接 http://www.mybringback.com/tutorial-series/13193/android-mysql-php-json-part-5-developing-the-android-application/

但每次我尝试登录时应用程序都会崩溃。我尝试使用错误的凭据登录，但它会得到相同的结果

我知道这个问题已被问过几次，但没有帮助

这是报告

09-25 16:32:53.762: E/AndroidRuntime(2616): FATAL EXCEPTION: AsyncTask #2
09-25 16:32:53.762: E/AndroidRuntime(2616): Process: com.learn2crack.tab, PID: 2616
09-25 16:32:53.762: E/AndroidRuntime(2616): java.lang.RuntimeException: An error occured while executing doInBackground()
09-25 16:32:53.762: E/AndroidRuntime(2616):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at java.lang.Thread.run(Thread.java:841)
09-25 16:32:53.762: E/AndroidRuntime(2616): Caused by: java.lang.NullPointerException
09-25 16:32:53.762: E/AndroidRuntime(2616):     at com.learn2crack.tab.Login$AttemptLogin.doInBackground(Login.java:129)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at com.learn2crack.tab.Login$AttemptLogin.doInBackground(Login.java:1)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
09-25 16:32:53.762: E/AndroidRuntime(2616):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
09-25 16:32:53.762: E/AndroidRuntime(2616):     ... 4 more

async

的codesnippet

class AttemptLogin extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(Login.this);
            pDialog.setMessage("Attempting login...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();

        }

        @Override
        protected String doInBackground(String... args) {
            // TODO Auto-generated method stub
            // Check for success tag
            int success;
            String username = user.getText().toString();
            String password = pass.getText().toString();
            try {
                // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                params.add(new BasicNameValuePair("username", username));
                params.add(new BasicNameValuePair("password", password));

                Log.d("request!", "starting");
                // getting product details by making HTTP request
                JSONObject json = jsonParser.makeHttpRequest(LOGIN_URL, "POST",
                        params);

                // check your log for json response
                Log.d("Login attempt", json.toString());

                // json success tag
                success = json.getInt(TAG_SUCCESS);
                if (success == 1) {
                    Log.d("Login Successful!", json.toString());
                    // save user data
                    SharedPreferences sp = PreferenceManager
                            .getDefaultSharedPreferences(Login.this);
                    Editor edit = sp.edit();
                    edit.putString("username", username);
                    edit.commit();

                    Intent i = new Intent(Login.this, MainActivity.class);
                    finish();
                    startActivity(i);
                    return json.getString(TAG_MESSAGE);
                } else {
                    Log.d("Login Failure!", json.getString(TAG_MESSAGE));
                    return json.getString(TAG_MESSAGE);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;

        }

        protected void onPostExecute(String file_url) {
            // dismiss the dialog once product deleted
            pDialog.dismiss();
            if (file_url != null) {
                Toast.makeText(Login.this, file_url, Toast.LENGTH_LONG).show();
            }

        }

Answer 1

使用android排球，它更快，有响应回调，运行并行线程，它使用缓存！ http://developer.android.com/training/volley/index.html

致命异常AsyncTask＃2？

1 个答案: