Question

I’m a bit lost on this one. How can I get an OutOfBounds? Is there a size limit (besides sizeof (int))?

Maybe because multiple threads can come here? The UI thread and a Service thread?

java.lang.ArrayIndexOutOfBoundsException at
kenyu73.realsignal.DatabaseWrapper.getSignalValues(DatabaseWrapper.java:137) at
kenyu73.realsignal.DatabaseWrapper.getSignalValues(DatabaseWrapper.java:116) at
kenyu73.realsignal.BarScaleGraph$buildGraphThread.drawGraph(BarScaleGraph.java:128)
at
kenyu73.realsignal.BarScaleGraph$buildGraphThread.execute(BarScaleGraph.java:94)
at
kenyu73.realsignal.BarScaleGraph$buildGraphThread.run(BarScaleGraph.java:74)

Also, I’m calling this classes methods with a static instance. I’m thinking threads are competing for the same variables??? Thoughts?

BarScaleGraph class

ContentValues[] values = DatabaseWrapper.getInstance().getSignalValues(getContentResolver(), signal_type, false);

DatabaseWrapper class

private static final DatabaseWrapper    instance    = new DatabaseWrapper();

// grab static instance so we only have one db wrapper
public static DatabaseWrapper getInstance() {
    return instance;
}

. . . .

public ContentValues[] getSignalValues(ContentResolver cr, int signal_type_id, boolean bGroupByLatLon) {

    String sWhere = "signal_type_id=" + signal_type_id;

    Cursor cursor;

    if (bGroupByLatLon) {
        cursor = cr.query(CONSTS.CONTENT_URI_GRP_LATLNG, null, sWhere, null, null);
    } else {
        cursor = cr.query(CONSTS.CONTENT_URI_LOGGER, null, sWhere, null, null);
    }

    ContentValues[] values = new ContentValues[cursor.getCount()];

    int count = 0;
    if (cursor.getCount() > 0) {
        cursor.moveToFirst();
        do {
            values[count] = new ContentValues(); // <--- LINE 137
            values[count].put("signal_value", cursor.getInt(cursor.getColumnIndex("signal_value")));
            values[count].put("latitude", cursor.getInt(cursor.getColumnIndex("latitude")));
            values[count].put("longitude", cursor.getInt(cursor.getColumnIndex("longitude")));
            values[count].put("timestamp", cursor.getLong(cursor.getColumnIndex("timestamp")));
            values[count].put("network", cursor.getString(cursor.getColumnIndex("network")));

            count++;

        } while (cursor.moveToNext());
    }
    cursor.close();

    return values;
}

EDIT: Going to try this – add synchronized to the instance

// grab static instance so we only have one db wrapper
public static synchronized DatabaseWrapper getInstance() {
    return instance;
}

Answer 1

I would guess this is a race condition, where the count is change between threads… try to synchronize the method:

public synchronized ContentValues[] getSignalValues(...){
    ...
}

If the previous does not fit you, there is always this:

public ContentValues[] method1(...){
    synchronized (monitor1) {
        ...
    }
}

public ContentValues[] method2(...){
    synchronized (monitor2) {
        ...
    }
}

This would solve the issue, but I would try to prevented this sort of methodology using different architecture.