I am reading a sqlite database into a tableLayout. I wan’t to do this in a seperate thread instead of having a long wait with no ui updates. So I used an AsyncTask to do some of the work and publish the results. However only about 1/4th of the item in my list actually make it on to the TableLayout. It works fine without the AsyncTask. Most of the items on the list throw an error (which I caught) java.util.concurrent.RejectedExecutionException. I’m not sure why this is. Here is my code.
myDB.execSQL("CREATE TABLE IF NOT EXISTS "
+ TableName
+ " (_id INTEGER PRIMARY KEY, filepath TEXT UNIQUE, title TEXT, artist TEXT, album TEXT, time TEXT, playcount NUMERIC);");
Cursor c = myDB.rawQuery("SELECT * FROM " + TableName, null);
c.moveToFirst();
if (c != null) {
int color = 0xFFdfe8ea;
this.startManagingCursor(c);
// Loop through all Results
do {
try{
MyAsyncTask aTask = new MyAsyncTask();
String[]strings= {c.getString(c.getColumnIndex("title")),c.getString(c.getColumnIndex("artist")),c.getString(c.getColumnIndex("time")),c.getString(c.getColumnIndex("album")),""+color};
aTask.execute(strings);
}catch(Exception e){
Log.w("****", e);
}
if (color == 0xFFdfe8ea) {
color = 0xFFf2f8fa;
} else {
color = 0xFFdfe8ea;
}
} while (c.moveToNext());
}
} catch (SQLException e) {
Log.e("****", e.toString());
} finally {
if (myDB != null) {
myDB.close();
}
}
and here is the AsyncTask
class MyAsyncTask extends AsyncTask<String, Void, View> {
@Override
protected View doInBackground(String... params) {
int color = Integer.parseInt(params[4]);
TableRow tr = new TableRow(MainActivity.this);
tr.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
TextView space = new TextView(MainActivity.this);
space.setText("");
space.setBackgroundColor(color); //0xFFf2f8fa alternating
space.setSingleLine();
space.setPadding(2, 2, 2, 2);
space.setGravity(Gravity.LEFT);
space.setTextColor(0xFF000000);
space.setLayoutParams(new LayoutParams(
findViewById(R.id.spaceColumn).getWidth(),
LayoutParams.WRAP_CONTENT));
/* Create a Button to be the row-content. */
TextView title = new TextView(MainActivity.this);
title.setText(params[0]);
title.setBackgroundColor(color); //0xFFf2f8fa alternating
title.setSingleLine();
title.setPadding(2, 2, 2, 2);
title.setGravity(Gravity.LEFT);
title.setTextColor(0xFF000000);
title.setEllipsize(TruncateAt.END);
title.setLayoutParams(new LayoutParams(
0,
LayoutParams.WRAP_CONTENT, 1));
/* Create a Button to be the row-content. */
TextView artist = new TextView(MainActivity.this);
artist.setText(params[1]);
artist.setBackgroundColor(color); //0xFFf2f8fa alternating
artist.setSingleLine();
artist.setPadding(2, 2, 2, 2);
artist.setGravity(Gravity.LEFT);
artist.setTextColor(0xFF000000);
artist.setEllipsize(TruncateAt.END);
artist.setLayoutParams(new LayoutParams(
0,
LayoutParams.WRAP_CONTENT, 1));
/* Create a Button to be the row-content. */
TextView time = new TextView(MainActivity.this);
time.setText(params[2]);
time.setBackgroundColor(color); //0xFFf2f8fa alternating
time.setSingleLine();
time.setPadding(2, 2, 2, 2);
time.setGravity(Gravity.LEFT);
time.setTextColor(0xFF000000);
time.setLayoutParams(new LayoutParams(
findViewById(R.id.timeColumn).getWidth(),
LayoutParams.WRAP_CONTENT));
/* Create a Button to be the row-content. */
TextView album = new TextView(MainActivity.this);
album.setText(params[3]);
album.setBackgroundColor(color); //0xFFf2f8fa alternating
album.setSingleLine();
album.setPadding(2, 2, 2, 2);
album.setGravity(Gravity.LEFT);
album.setTextColor(0xFF000000);
album.setEllipsize(TruncateAt.END);
album.setLayoutParams(new LayoutParams(
0,
LayoutParams.WRAP_CONTENT, 1));
/* Add Button to row. */
tr.addView(space);
tr.addView(title);
tr.addView(artist);
tr.addView(time);
tr.addView(album);
/* Add row to TableLayout. */
return tr;
}
@Override
protected void onPostExecute(View tr) {
((TableLayout) findViewById(R.id.tableLayout)).addView(tr, new TableLayout.LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
}
@Override
protected void onPreExecute() {
}
}
For reference this is how I fixed it.
class MyAsyncTask extends AsyncTask<Void, Song, Void> {
@Override
protected Void doInBackground(Void... params) {
SQLiteDatabase myDB = openOrCreateDatabase("DatabaseName", MODE_PRIVATE, null);
String TableName = "songs";
myDB.execSQL("CREATE TABLE IF NOT EXISTS "
+ TableName
+ " (_id INTEGER PRIMARY KEY, filepath TEXT UNIQUE, title TEXT, artist TEXT, album TEXT, time TEXT, playcount NUMERIC);");
Cursor c = myDB.rawQuery("SELECT * FROM " + TableName, null);
c.moveToFirst();
int filepathIndex=c.getColumnIndex("filepath");
int titleIndex=c.getColumnIndex("title");
int artistIndex=c.getColumnIndex("artist");
int albumIndex=c.getColumnIndex("album");
int timeIndex=c.getColumnIndex("time");
int playcountIndex=c.getColumnIndex("playcount");
if (c != null) {
int color = 0xFFdfe8ea;
// this.startManagingCursor(c);
// Loop through all Results
do {
Song song = new Song(c.getString(filepathIndex),c.getString(titleIndex),c.getString(artistIndex),c.getString(albumIndex),c.getString(timeIndex),c.getInt(playcountIndex),color);
// Add to song the data from your cursor
publishProgress(song);
if (color == 0xFFdfe8ea) {
color = 0xFFf2f8fa;
} else {
color = 0xFFdfe8ea;
}
} while (c.moveToNext());
}
return null;
}
@Override
protected void onPostExecute(Void item) {
}
@Override
protected void onPreExecute() {
}
@Override
protected void onProgressUpdate(Song... items) {
for (Song song : items) {
TableRow tr = new TableRow(MainActivity.this);
tr.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
TextView space = new TextView(MainActivity.this);
space.setText("");
space.setBackgroundColor(song.color); //0xFFf2f8fa alternating
space.setSingleLine();
space.setPadding(2, 2, 2, 2);
space.setGravity(Gravity.LEFT);
space.setTextColor(0xFF000000);
space.setLayoutParams(new LayoutParams(
findViewById(R.id.spaceColumn).getWidth(),
LayoutParams.WRAP_CONTENT));
/* Create a Button to be the row-content. */
TextView title = new TextView(MainActivity.this);
title.setText(song.title);
title.setBackgroundColor(song.color); //0xFFf2f8fa alternating
title.setSingleLine();
title.setPadding(2, 2, 2, 2);
title.setGravity(Gravity.LEFT);
title.setTextColor(0xFF000000);
title.setEllipsize(TruncateAt.END);
title.setLayoutParams(new LayoutParams(
0,
LayoutParams.WRAP_CONTENT, 1));
/* Create a Button to be the row-content. */
TextView artist = new TextView(MainActivity.this);
artist.setText(song.artist);
artist.setBackgroundColor(song.color); //0xFFf2f8fa alternating
artist.setSingleLine();
artist.setPadding(2, 2, 2, 2);
artist.setGravity(Gravity.LEFT);
artist.setTextColor(0xFF000000);
artist.setEllipsize(TruncateAt.END);
artist.setLayoutParams(new LayoutParams(
0,
LayoutParams.WRAP_CONTENT, 1));
/* Create a Button to be the row-content. */
TextView time = new TextView(MainActivity.this);
time.setText(song.time);
time.setBackgroundColor(song.color); //0xFFf2f8fa alternating
time.setSingleLine();
time.setPadding(2, 2, 2, 2);
time.setGravity(Gravity.LEFT);
time.setTextColor(0xFF000000);
time.setLayoutParams(new LayoutParams(
findViewById(R.id.timeColumn).getWidth(),
LayoutParams.WRAP_CONTENT));
/* Create a Button to be the row-content. */
TextView album = new TextView(MainActivity.this);
album.setText(song.album);
album.setBackgroundColor(song.color); //0xFFf2f8fa alternating
album.setSingleLine();
album.setPadding(2, 2, 2, 2);
album.setGravity(Gravity.LEFT);
album.setTextColor(0xFF000000);
album.setEllipsize(TruncateAt.END);
album.setLayoutParams(new LayoutParams(
0,
LayoutParams.WRAP_CONTENT, 1));
/* Add Button to row. */
tr.addView(space);
tr.addView(title);
tr.addView(artist);
tr.addView(time);
tr.addView(album);
// Add the row to the table
((TableLayout) findViewById(R.id.tableLayout)).addView(tr, new TableLayout.LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
}
}
}
If you want to do it using an AsyncTask, consider using
publishProgress(), that way each item will be added as it is fetched from the database. This way:NOTE: Consider that
Songis a class withname,album,artistandtimeattributes.I believe you understood the concept behind AsyncTask wrongly, I strongly suggest you reread its documentation at Android Developers as its concept is a bit tricky to understand but very powerfull when you do so. As Romain Guy commented on your answer you can only execute UI code on the onPreExecute(), onProgressUpdate() and onPostExecute() methods.