Android - Displaying Cursor Results from DB in ListView

Question

I have been trying to get my Cursor to display correctly in listview. it displays correctly when using a toast so the cursor is retrieving the data correctly but i'm having trouble making it display in list format.

Should be 6 columns in each row.

It only displays one row with no data. I'm sure it is a very basic problem. Maybe somebody could tell me where I'm going wrong, I would be grateful.

DisplayCursor.Java

public class DisplayCursor extends ListActivity 
{
MyDBManager db = new MyDBManager(this);

@Override
public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display_cursor);

    db.open();
    Cursor cursor = db.getAllRows();
    startManagingCursor(cursor);

    String[] columns = new String[] { MyDBManager.KEY_DESCRIPTION, MyDBManager.KEY_PERCENTAGE, MyDBManager.KEY_PRICE, 
            MyDBManager.KEY_VOLUME, MyDBManager.KEY_VFM, MyDBManager.KEY_QUANTITY };

    int[] to = new int[] { R.id.description,R.id.perc,R.id.price,R.id.units,R.id.vol, R.id.vfm };
    SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this, R.layout.row, cursor, columns, to);
    this.setListAdapter(mAdapter);
    db.close();
}   
}

row.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >

<TextView
    android:id="@+id/description"
    android:layout_width="140dp"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="27dp" />

<TextView
    android:id="@+id/vol"
    android:layout_width="30dp"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/description"
    android:layout_alignBottom="@+id/description"
    android:layout_toRightOf="@+id/description" />

<TextView
    android:id="@+id/perc"
    android:layout_width="30dp"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/vol"
    android:layout_alignBottom="@+id/vol"
    android:layout_toRightOf="@+id/vol" />

<TextView
    android:id="@+id/price"
    android:layout_width="30dp"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/perc"
    android:layout_alignBottom="@+id/perc"
    android:layout_toRightOf="@+id/perc" />

<TextView
    android:id="@+id/units"
    android:layout_width="30dp"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/price"
    android:layout_alignBottom="@+id/price"
    android:layout_toRightOf="@+id/price" />

<TextView
    android:id="@+id/vfm"
    android:layout_width="80dp"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/units"
    android:layout_alignBottom="@+id/units"
    android:layout_toRightOf="@+id/units" />

</RelativeLayout>

activity_display_cursor.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content">

<ListView android:id="@android:id/list"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

<TextView android:id="@android:id/empty"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/nodata"/>

</LinearLayout>

Offtopic: Why are you using a ListActivity if you're setting a content view with a LinearLayout as the parent? — tolgap
– tolgap, Commented Nov 13, 2012 at 23:46

Joe Malin · Accepted Answer · 2012-11-13 21:24:56Z

4

Ah, ListView with CursorAdapter strikes again! It's not easy to grok the first time round, so:

You have most of it correct, however, your row.xml needs to contain a View for each column in the cursor you want to display. The "layout" argument in the CursorAdapter constructor specifies the resID of a layout file; this file describes one row. In your case, you probably want a RelativeLayout that has 6 TextViews in it, one for each of the R.id values in the "to" argument to the constructor. The CursorAdapter takes care of mapping the cursor columns to the views in the "to" argument, which is why the size of those arrays has to be the same.

The activity_display_cursor.xml layout defines the ListView.

As a note, I don't use ListActivity much. It's easy enough to set up a ListView with an adapter in a regular Activity. Also, startManagingCursor was deprecated in API 11. A better choice is to use android.support.v4.content.CursorLoader and android.support.v4.widget.SimpleCursorAdapter.

answered Nov 13, 2012 at 21:24

Joe Malin

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2 Comments

Ron Over a year ago

Thanks for all your help so far! Now everything compiles just fine. But there's a blank row appearing on screen for every.. row in my cursor. I must be missing something in that row.xml?

tolgap Over a year ago

The values in the int[] to must match the IDs of the TextViews in row.xml.

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