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POCustom SimpleCursorAdapter, database query and NullPointerException
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copied!<p>I'm trying to make ListView populated from database, and spice each row with fancy delete button. So I made list Activity and custom SimpleCursorAdapter.</p> <p>This is main ListView activity:</p> <pre><code> public class EditEntries extends ListActivity { Cursor cursor; DBAdapter db = new DBAdapter(this); private static String[] FROM = { _ID, SCORE_COLUMN, "date(time, 'localtime')", }; private static int[] TO = { R.id.rowid, R.id.title, R.id.time, }; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.entries_list); try { cursor = getEvents(); showEvents(cursor); } finally { db.close(); } } private void showEvents(Cursor cursor) { // Set up data binding SMSimpleCursorAdapter adapter = new SMSimpleCursorAdapter(this, R.layout.entries_list_item, cursor, FROM, TO); setListAdapter(adapter); } private Cursor getEvents() { db.open(); cursor = db.getAllScores(); startManagingCursor(cursor); return cursor; } void delRow() { // this is method for deleting row by _id db.open(); db.deleteScore(3); // here will be TAG with _id from adapter, db.close(); // for now I just use hardcoded _id } } </code></pre> <p>And this is custom SimpleCursorAdapter:</p> <pre><code> public class SMSimpleCursorAdapter extends SimpleCursorAdapter{ Cursor c; Context context; Activity activity; public SMSimpleCursorAdapter(Context context, int layout, Cursor c, String[] from, int[] to) { super(context, layout, c, from, to); this.c = c; this.context=context; this.activity=(Activity) context; } EditEntries dbDel = new EditEntries(); //from previous code sample @Override public View getView(int position, View convertView, ViewGroup parent) { if(convertView == null) convertView = View.inflate(context, R.layout.entries_list_item, null); View row = convertView; c.moveToPosition(position); TextView score = (TextView) convertView.findViewById(R.id.title); TextView time = (TextView) convertView.findViewById(R.id.time); TextView id = (TextView) convertView.findViewById(R.id.rowid); id.setText(c.getString(0)); time.setText(c.getString(2)); score.setText(c.getString(1)); String daTag = c.getString(1); ImageButton delButton = (ImageButton) convertView.findViewById(R.id.delButton); delButton.setFocusable(true); delButton.setClickable(true); //delButton.setTag(daTag); delButton.setOnClickListener(new OnClickListener() { //Click listener fro delete button @Override public void onClick(View view) { dbDel.delRow(); //this is "delete row" method from previos code sample } }); return(row); } } </code></pre> <p>And all this stuff gives me NullPointerException when I click delete button. I'm new to android, and suppose that I just missed something obvious.</p> <p>LogCat:</p> <blockquote> <p>ERROR/AndroidRuntime(14027): FATAL EXCEPTION: main</p> <p>ERROR/AndroidRuntime(14027): java.lang.NullPointerException</p> <p>ERROR/AndroidRuntime(14027): at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203)</p> <p>ERROR/AndroidRuntime(14027): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:98)</p> <p>ERROR/AndroidRuntime(14027): at namespace.DBAdapter.open(DBAdapter.java:66)</p> <p>ERROR/AndroidRuntime(14027): at namespace.EditEntries.delRow(EditEntries.java:50)</p> <p>ERROR/AndroidRuntime(14027): at namespace.SMSimpleCursorAdapter$1.onClick(SMSimpleCursorAdapter.java:64)</p> <p>ERROR/AndroidRuntime(14027): at android.view.View.performClick(View.java:2414)</p> <p>ERROR/AndroidRuntime(14027): at android.view.View$PerformClick.run(View.java:8838)</p> <p>ERROR/AndroidRuntime(14027): at android.os.Handler.handleCallback(Handler.java:587)</p> <p>ERROR/AndroidRuntime(14027): at android.os.Handler.dispatchMessage(Handler.java:92)</p> <p>ERROR/AndroidRuntime(14027): at android.os.Looper.loop(Looper.java:123)</p> <p>ERROR/AndroidRuntime(14027): at android.app.ActivityThread.main(ActivityThread.java:4680)</p> <p>ERROR/AndroidRuntime(14027): at java.lang.reflect.Method.invokeNative(Native Method)</p> <p>ERROR/AndroidRuntime(14027): at java.lang.reflect.Method.invoke(Method.java:521)</p> <p>ERROR/AndroidRuntime(14027): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)</p> <p>ERROR/AndroidRuntime(14027): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)</p> <p>ERROR/AndroidRuntime(14027): at dalvik.system.NativeStart.main(Native Method)</p> </blockquote>

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