Databases
StackOverflow2013
Postsdbo
PONull pointer exception error : database in android
Body
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PONull pointer exception error : database in android
    text
    copied!<p>Im having troubles with displaying one Event information from my database. After clicking on my Event from event list in DayPlan.java it should show me some informations about this event but it simply crashes whole application with error : Nullpointer exception :( I used thiscodeasa base: <a href="http://vimaltuts.com/android-tutorial-for-beginners/android-sqlite-database-example" rel="nofollow">Database example</a></p> <p>error is somewhere in OnPostExecute from ViewEvent, could anyone please help me? </p> <p>my database connector: </p> <pre><code> package com.examples.android.calendar; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; public class DatabaseConnector { private static final String DB_NAME = "watchaday"; private SQLiteDatabase database; private DatabaseOpenHelper dbOpenHelper; public DatabaseConnector(Context context) { dbOpenHelper = new DatabaseOpenHelper(context, DB_NAME, null, 1); } public void open() throws SQLException { //open database in reading/writing mode database = dbOpenHelper.getWritableDatabase(); } public void close() { if (database != null) database.close(); } public void insertContact(String date, String hour_from, String hour_to, String event, String colour) { ContentValues newCon = new ContentValues(); newCon.put("date", date); newCon.put("hour_from", hour_from); newCon.put("hour_to", hour_to); newCon.put("event", event); newCon.put("colour", colour); open(); database.insert("calendar_events", null, newCon); close(); } public void updateContact(long id, String date, String hour_from, String hour_to, String event, String colour) { ContentValues editCon = new ContentValues(); ; editCon.put("date", date); editCon.put("hour_from", hour_from); editCon.put("hour_to", hour_to); editCon.put("event", event); editCon.put("colour", colour); open(); database.update("calendar_events", editCon, "_id=" + id, null); close(); } public Cursor getAllContacts() { return database.query("calendar_events", new String[] {"_id", "event"}, null, null, null, null, "date"); } public Cursor getOneContact(long id) { return database.query("calendar_events", null, "_id=" + id, null, null, null, null); } public void deleteContact(long id) { open(); database.delete("calendar_events", "_id=" + id, null); close(); } } </code></pre> <p>my database Helper:</p> <pre><code> package com.examples.android.calendar; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteDatabase.CursorFactory; import android.database.sqlite.SQLiteOpenHelper; public class DatabaseOpenHelper extends SQLiteOpenHelper { public DatabaseOpenHelper(Context context, String name, CursorFactory factory, int version) { super(context, name, factory, version); } @Override public void onCreate(SQLiteDatabase db) { String createQuery = "CREATE TABLE calendar_events (_id integer primary key autoincrement,date, hour_from, hour_to, event, colour);"; db.execSQL(createQuery); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { } } </code></pre> <p>my Event List code : </p> <pre><code> package com.examples.android.calendar; import android.os.AsyncTask; import android.os.Bundle; import android.app.ListActivity; import android.content.Intent; import android.database.Cursor; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView; import android.widget.CursorAdapter; import android.widget.ListView; import android.widget.SimpleCursorAdapter; import android.widget.AdapterView.OnItemClickListener; public class DayPlan extends ListActivity { public static final String ROW_ID = "row_id"; private ListView conListView; private CursorAdapter conAdapter; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); conListView=getListView(); conListView.setOnItemClickListener(viewConListener); // map each name to a TextView String[] from = new String[] { "event" }; int[] to = new int[] { R.id.countryTextView }; conAdapter = new SimpleCursorAdapter(DayPlan.this, R.layout.day_plan, null, from, to); setListAdapter(conAdapter); // set adapter } @Override protected void onResume() { super.onResume(); new GetContacts().execute((Object[]) null); } @Override protected void onStop() { Cursor cursor = conAdapter.getCursor(); if (cursor != null) cursor.deactivate(); conAdapter.changeCursor(null); super.onStop(); } private class GetContacts extends AsyncTask&lt;Object, Object, Cursor&gt; { DatabaseConnector dbConnector = new DatabaseConnector(DayPlan.this); @Override protected Cursor doInBackground(Object... params) { dbConnector.open(); return dbConnector.getAllContacts(); } @Override protected void onPostExecute(Cursor result) { conAdapter.changeCursor(result); // set the adapter's Cursor dbConnector.close(); } } @Override public boolean onCreateOptionsMenu(Menu menu) { super.onCreateOptionsMenu(menu); MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.dayplan_menu, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { Intent addContact = new Intent(DayPlan.this, AddEvent.class); startActivity(addContact); return super.onOptionsItemSelected(item); } OnItemClickListener viewConListener = new OnItemClickListener() { public void onItemClick(AdapterView&lt;?&gt; arg0, View arg1, int arg2,long arg3) { Intent viewCon = new Intent(DayPlan.this, ViewEvent.class); viewCon.putExtra(ROW_ID, arg3); startActivity(viewCon); } }; } </code></pre> <p>my View event code which crashes application in OnPostExecute part:</p> <p>ViewEvent.java : </p> <pre><code>public class ViewEvent extends Activity { private long rowID; private TextView dateTv; private TextView hourfromTv; private TextView hourtoTv; private TextView eventTv; private TextView colourTv; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.view_event); setUpViews(); Bundle extras = getIntent().getExtras(); rowID = extras.getLong(DayPlan.ROW_ID); } private void setUpViews() { dateTv = (TextView) findViewById(R.id.date); hourfromTv = (TextView) findViewById(R.id.hour_fromText); hourtoTv = (TextView) findViewById(R.id.hour_toText); eventTv = (TextView) findViewById(R.id.eventText); colourTv = (TextView) findViewById(R.id.colourText); } @Override protected void onResume() { super.onResume(); new LoadContacts().execute(rowID); } private class LoadContacts extends AsyncTask&lt;Long, Object, Cursor&gt; { DatabaseConnector dbConnector = new DatabaseConnector(ViewEvent.this); @Override protected Cursor doInBackground(Long... params) { dbConnector.open(); return dbConnector.getOneContact(params[0]); } @Override protected void onPostExecute(Cursor result) { super.onPostExecute(result); result.moveToFirst(); // get the column index for each data item int dateindex = result.getColumnIndex("date"); int hourfromIndex = result.getColumnIndex("hour_from"); int hourtoIndex = result.getColumnIndex("hour_to"); int eventIndex = result.getColumnIndex("event"); int colourIndex = result.getColumnIndex("colour"); dateTv.setText(result.getString(dateindex)); hourfromTv.setText(result.getString(hourfromIndex)); hourtoTv.setText(result.getString(hourtoIndex)); eventTv.setText(result.getString(eventIndex)); colourTv.setText(result.getString(colourIndex)); result.close(); dbConnector.close(); } } @Override public boolean onCreateOptionsMenu(Menu menu) { super.onCreateOptionsMenu(menu); MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.view_event_menu, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.editItem: Intent addEditContact = new Intent(this, AddEvent.class); addEditContact.putExtra(DayPlan.ROW_ID, rowID); startActivity(addEditContact); return true; case R.id.deleteItem: deleteContact(); return true; default: return super.onOptionsItemSelected(item); } } private void deleteContact() { AlertDialog.Builder alert = new AlertDialog.Builder(ViewEvent.this); alert.setTitle(R.string.confirmTitle); alert.setMessage(R.string.confirmMessage); alert.setPositiveButton(R.string.delete_btn, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int button) { final DatabaseConnector dbConnector = new DatabaseConnector(ViewEvent.this); AsyncTask&lt;Long, Object, Object&gt; deleteTask = new AsyncTask&lt;Long, Object, Object&gt;() { @Override protected Object doInBackground(Long... params) { dbConnector.deleteContact(params[0]); return null; } @Override protected void onPostExecute(Object result) { finish(); } }; deleteTask.execute(new Long[] { rowID }); } } ); alert.setNegativeButton(R.string.cancel_btn, null).show(); } } </code></pre> <p>Error : </p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): FATAL EXCEPTION: main</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): java.lang.NullPointerException</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at com.examples.android.calendar.ViewEvent$LoadContacts.onPostExecute(ViewEvent.java:76)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at com.examples.android.calendar.ViewEvent$LoadContacts.onPostExecute(ViewEvent.java:1)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at android.os.AsyncTask.finish(AsyncTask.java:631)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at android.os.AsyncTask.access$600(AsyncTask.java:177)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at android.os.Handler.dispatchMessage(Handler.java:99)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at android.os.Looper.loop(Looper.java:137)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at android.app.ActivityThread.main(ActivityThread.java:4745)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at java.lang.reflect.Method.invokeNative(Native Method)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at java.lang.reflect.Method.invoke(Method.java:511)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)</p> <p>12-30 17:52:29.334: E/AndroidRuntime(1173): at dalvik.system.NativeStart.main(Native Method) 12-30 17:52:31.463: I/Process(1173): Sending signal. PID: 1173 SIG: 9 12-30 17:52:32.305: E/Trace(1191): error opening trace file: No such file or directory (2)</p>
 

Querying!

 
Guidance
An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload