The problem is as follows. I have a login activity (in Android Studio) which worked fine a few days before. I don't remember changing anything but when I run this one the previous time the app closed right after I clicked the login button. The last thing indicated was the toast about pre-execution of AsyncTask. And I can't understand why there could be a NullPointerException. I have almost the same code for my signup activity and it works fine.
Here is the log:
EDIT 1
I had my eyes opened, the problem is not with LoginActivity, but with HomepageActivity. Here is the code:
import ... public class HomepageActivity extends Activity implements AdapterView.OnItemSelectedListener { protected EditText mAddTaskText; protected Spinner mPrioritySpinner; protected Button mAddTaskButton; protected int intPriority = 0; protected String taskText; protected Timestamp taskTimestamp; protected Task userTask; protected JsonGenerator taskJSON; @Override protected void onCreate(Bundle savedInstanceState) { // Starts activity. The state can be restored from savedInstanceState super.onCreate(savedInstanceState); // Calls the superclass method (IMPORTANT) setContentView(R.layout.activity_homepage); // Sets layout from activity_homepage.xml mPrioritySpinner = (Spinner) findViewById(R.id.prioritySpinner); // Creates an ArrayAdapter using the string array and a default spinner layout ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.priorityList, android.R.layout.simple_spinner_item); // Specifies the layout to use when the list of choices appears adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); // Applies the adapter to the spinner mPrioritySpinner.setAdapter(adapter); mPrioritySpinner.setOnItemSelectedListener(this); mAddTaskText = (EditText) findViewById(R.id.addTaskEditText); // Finds View by its id in .xml file mAddTaskButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Toast.makeText(HomepageActivity.this, "Done!", Toast.LENGTH_LONG).show(); Calendar taskCalendar = Calendar.getInstance(); // Creates new calendar long taskTime = taskCalendar.getTimeInMillis(); // Gets time in milliseconds taskTimestamp = new Timestamp(taskTime); // Creates new Timestamp taskText = mAddTaskText.getText().toString(); // Gets description of the task userTask.setDate(taskTimestamp); // Sets date userTask.setText(taskText); // Sets text /* Creating JsonGenerator */ ObjectMapper mapper = new ObjectMapper(); try { mapper.writeValue(taskJSON, userTask); } catch (IOException e) { Toast.makeText(HomepageActivity.this, "Could not create JSON", Toast.LENGTH_LONG).show(); } /* Getting out email and password */ String userPassword = ((EmailPassword) HomepageActivity.this.getApplication()).getPassword(); String userEmail = ((EmailPassword) HomepageActivity.this.getApplication()).getUserEmail(); Toast.makeText(HomepageActivity.this, userEmail + " " + userPassword, Toast.LENGTH_LONG).show(); /* HTTP stuff */ HttpPoster get = new HttpPoster(); get.execute(userEmail, userPassword, taskJSON.toString()); } }); } public int getData (String username, String password, String taskJSON) { try { HttpPost httpPost = new HttpPost("http://something.com/" + username + "/tasks"); String dataToEncode = username + ":" + password; String encodedData = Base64.encodeToString(dataToEncode.getBytes(), Base64.NO_WRAP); httpPost.setHeader("Authorization", encodedData); try { StringEntity taskEntity = new StringEntity(taskJSON, "UTF-8"); httpPost.setEntity(taskEntity); } catch (UnsupportedEncodingException e) { Toast.makeText(HomepageActivity.this, "Unsupported encoding", Toast.LENGTH_LONG).show(); } HttpClient client = new DefaultHttpClient(); HttpResponse response = client.execute(httpPost); StatusLine statusLine = response.getStatusLine(); int statusCode = statusLine.getStatusCode(); if (statusCode == 200) { return 1; } else if (statusCode == 404) { return 2; } else if (statusCode == 500) { return 3; } else if (statusCode == 409) { return 4; } else { return statusCode; } } catch (IOException e) { e.printStackTrace(); } return 0; } public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) { String priority = parent.getItemAtPosition(pos).toString(); // Gets chosen priority Toast.makeText(HomepageActivity.this, priority, Toast.LENGTH_LONG).show(); while (!((priority.equals("Low")) || (priority.equals("Medium")) || (priority.equals("High")))) { Toast.makeText(HomepageActivity.this, "Something bad happened. Try to choose again", Toast.LENGTH_LONG).show(); } if (priority.equals("Low")) { intPriority = 0; } else if (priority.equals("Medium")) { intPriority = 1; } else if (priority.equals("High")) { intPriority = 2; } userTask.setPriority(intPriority); // Sets chosen priority } public void onNothingSelected(AdapterView<?> parent) { userTask.setPriority(intPriority); // Sets default priority ("0") } public class HttpPoster extends AsyncTask<String, Void, Integer> { @Override protected void onPreExecute() { super.onPreExecute(); } @Override protected Integer doInBackground(String... params) { return getData(params[0], params[1], params[3]); } @Override protected void onPostExecute(Integer result) { super.onPostExecute(result); if (result == 1) { Toast.makeText(HomepageActivity.this, "Login successful", Toast.LENGTH_LONG).show(); Intent takeUserHome = new Intent(HomepageActivity.this, HomepageActivity.class); startActivity(takeUserHome); } else if (result == 2) { Toast.makeText(HomepageActivity.this, "No such user", Toast.LENGTH_LONG).show(); } else if (result == 3) { Toast.makeText(HomepageActivity.this, "Internal server error: unable to send email", Toast.LENGTH_LONG).show(); } else if (result == 4) { Toast.makeText(HomepageActivity.this, "Task already exists", Toast.LENGTH_LONG).show(); } else { Toast.makeText(HomepageActivity.this, result.toString(), Toast.LENGTH_LONG).show(); } } } } And XML file:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" android:paddingBottom="@dimen/activity_vertical_margin" tools:context="utanashati.testapp.HomepageActivity"> <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="Add a new task..." android:id="@+id/addTaskEditText" android:nestedScrollingEnabled="false" android:minLines="1" android:maxLines="1" /> <Spinner android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/prioritySpinner" android:layout_alignRight="@+id/addTaskButton" android:layout_alignEnd="@+id/addTaskButton" android:layout_below="@+id/addTaskEditText" /> <Button android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Add task" android:id="@+id/addTaskButton" android:layout_below="@+id/prioritySpinner" android:layout_centerHorizontal="true" /> </RelativeLayout>