I’m making a simple task list app, and I’m using a database to hold everything. I wrote up a custom CursorAdapter, extending ResourceCursorAdapter, to handle the data. Everything displays fine, but once you start going beyond that, things get sketchy. First, my implementation:
import android.app.AlertDialog;
import android.content.Context;
import android.database.Cursor;
import android.support.v4.widget.ResourceCursorAdapter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.Filterable;
import android.widget.LinearLayout;
import android.widget.TextView;
/**
* @author Dave Smith
*
*/
public class TaskCursorAdapter extends ResourceCursorAdapter {
/**
* @param context
* @param layout
* @param c
* @param from
* @param to
* @param flags
*/
private Context context;
private int layout, isCheckedFromDb, IdFromDb;
private Cursor cursor;
public TaskCursorAdapter(Context context, int layout, Cursor c,
int flags) {
super(context, layout, c, flags);
this.context = context;
this.layout = layout;
}
public TaskCursorAdapter(Context context, int layout){
super(context, layout, null, 0);
this.context = context;
this.layout = layout;
}
public TaskCursorAdapter(Context context, int layout, Cursor c){
super(context, layout, c, 0);
this.context = context;
this.layout = layout;
}
public TaskCursorAdapter(Context context, int layout, Cursor cursor, boolean autoRequery)
{
super(context, layout, cursor, autoRequery);
this.context = context;
this.layout = layout;
}
public View newView(Context context, Cursor cursor, ViewGroup parent){
final LayoutInflater inflater = LayoutInflater.from(context);
View v = inflater.inflate(layout, parent, false);
return v;
}
public void bindView(View v, Context context, Cursor c){
CheckBox taskCheckBox = (CheckBox)v.findViewById(R.id.taskCheckBox);
TextView taskText = (TextView)v.findViewById(R.id.taskTitle);
TextView taskNote = (TextView)v.findViewById(R.id.taskNote);
final long assignedID = v.getID();
//v.setClickable(true);
//LinearLayout holder = (LinearLayout)v.findViewById(R.id.container);
//holder.setClickable(true);
//IdFromDb = c.getInt(c.getColumnIndex(NagTasksDatabaseHelper.ID));
taskText.setText(c.getString(c.getColumnIndex(NagTasksDatabaseHelper.TASK)));
taskNote.setText(c.getString(c.getColumnIndex(NagTasksDatabaseHelper.NOTE)));
//isCheckedFromDb = c.getInt(c.getColumnIndex(NagTasksDatabaseHelper.CHECKED));
taskCheckBox.setChecked(c.getInt(c.getColumnIndex(NagTasksDatabaseHelper.CHECKED))==1);
//cursor = c;
taskCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
//Really Old method:
/*NagTasksDatabaseHelper helper = new NagTasksDatabaseHelper(null);
int idCol = cursor.getColumnIndex(NagTasksDatabaseHelper.ID);
int taskID = helper.getNewTaskId();
if (idCol!=-1)
{
taskID= cursor.getInt(idCol);
if (isChecked){
helper.checkOffTask(taskID);
} else {
helper.uncheckTask(taskID);
}
}
//TODO Solve how to use helper to change ISCHECKED in database
helper.close();
//Old method:
NagTasksDatabaseHelper helper = new NagTasksDatabaseHelper(null);
if (isChecked) {
helper.checkOffTask(IdFromDb);
} else {
helper.uncheckTask(IdFromDb);
}
helper.close();*/
//Current method:
if (assignedID!=View.NO_ID) {
NagTasksDatabaseHelper helper = new NagTasksDatabaseHelper(buttonView.getContext());
if (isChecked) {
helper.checkOffTask(assignedID);
} else {
helper.uncheckTask(assignedID);
}
helper.close();
} else {
AlertDialog.Builder builder = new AlertDialog.Builder(buttonView.getContext());
builder.setMessage("No ID found. Try something else.");
builder.setCancelable(true);
builder.create().show();
}
}
});
}
}
Issue 1
EDIT: Issue has been resolved, though I do not know how.
In it’s current state, I get an error in Eclipse’s console when I hit run. It doesn’t effect how well it runs at all, but in a previous implementation where I used a layout that only had a CheckBox and just changed the CheckBox’s text, this error didn’t appear:
[2012-06-18 16:10:15 - ddms] null
java.lang.NullPointerException
at com.android.ddmlib.JdwpPacket.writeAndConsume(JdwpPacket.java:213)
at com.android.ddmlib.Client.sendAndConsume(Client.java:575)
at com.android.ddmlib.HandleHello.sendHELO(HandleHello.java:142)
at com.android.ddmlib.HandleHello.sendHelloCommands(HandleHello.java:65)
at com.android.ddmlib.Client.getJdwpPacket(Client.java:672)
at com.android.ddmlib.MonitorThread.processClientActivity(MonitorThread.java:317)
at com.android.ddmlib.MonitorThread.run(MonitorThread.java:263)
[2012-06-18 16:10:15 - ddms] null
java.lang.NullPointerException
at com.android.ddmlib.JdwpPacket.writeAndConsume(JdwpPacket.java:213)
at com.android.ddmlib.Client.sendAndConsume(Client.java:575)
at com.android.ddmlib.HandleHello.sendHELO(HandleHello.java:142)
at com.android.ddmlib.HandleHello.sendHelloCommands(HandleHello.java:65)
at com.android.ddmlib.Client.getJdwpPacket(Client.java:672)
at com.android.ddmlib.MonitorThread.processClientActivity(MonitorThread.java:317)
at com.android.ddmlib.MonitorThread.run(MonitorThread.java:263)
Issue 2
The ListFragment that is using this CursorAdapter is not performing its OnListItemClick() method. Similarly, I have registered the ListFragment’s ListView to use a ContextMenu (with registerForContextMenu()), but long-press does not bring up the context menu.
Issue 3
Uncommenting taskCheckBox.setOnCheckedChangeListener generally causes bad things to happen when the checkBox is checked. Typically, it’ll throw a null pointer exception and crash, because it doesn’t know for what _id to call checkOffTask() or uncheckTask(). (EDIT: The changes made in the most recent edit… still don’t do what I want it to do, but at least it doesn’t crash. Also annoying that getItemId() asks for a position and I don’t know how to retrieve that for a given item in a ListView from the cursor, or I’d use that.)
Could anyone help me solve these issues? I’m still mostly unclear of how CursorAdapters work, in spite of asking for help on this subject before.
EDIT: I should note that my app has another list that uses a very lightly tweaked ResourceCursorAdapter (see linked question), and none of these issues have popped up there. (Although issue 3 has no reason to pop up, as it’s a simple list of strings.)
ISSUE 1:
Will skip, as it’s been resolved.
ISSUE 2:
As noted in this previous question, if a view has a focusable object, it’ll be impossible to make the whole view clickable due to a bug in the SDK. So, I went into the inflated XML and added the attribute
android:focusable="false"to each item. List Items are now clickable and long-clickable.ISSUE 3:
As noted by a nice fellow on reddit, I was on the right track with the "Old Method" but needed to use a local
final longinstead of a parameter.