具有SimpleCursorAdapter的android ViewBinder

Question

I would like to know if my solution using a ViewBinder is correct and suitable for my problem.

I have implememented a ContentProvider. The startactivity extends ListActivity and displays all the entries from a sqliteDB using my contentprovider. A Click on one of the entries in the listview starts another activity showing detailinformation about this entry:

    public void onItemClick(AdapterView<?> parent, View view, int position,
        long id) {
    // Arzneimittel wurde durch Klick ausgewählt --> Detailansicht anzeigen
    Intent intent = new Intent(this, MedikamenteDetailActivity.class);
    intent.putExtra("_ID", id);
    startActivity(intent);
}

This is the layout of the Detail-Activity:

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/txtV_heading_statusinfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/heading_status_info"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <ListView
        android:id="@+id/datalist"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
    </ListView>

    <TextView
        android:id="@+id/txtV_PhZnr"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/hint_phznr"
        android:text="TextView" />

    <TextView
        android:id="@+id/txtV_Znr"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/znr"
        android:text="TextView" />

    <TextView
        android:id="@+id/txtV_SName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/sname"
        android:text="Small Text"
        android:textAppearance="?android:attr/textAppearanceSmall" />

    <TextView
        android:id="@+id/txtV_OName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/oname"
        android:text="Small Text"
        android:textAppearance="?android:attr/textAppearanceSmall" />

    <TextView
        android:id="@+id/txtV_DoLC"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/dolc"
        android:text="Small Text"
        android:textAppearance="?android:attr/textAppearanceSmall" />

</LinearLayout>

The Detail - Activity Class:

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_medikamente_detail);

        _id = String.valueOf(getIntent().getExtras().getLong("_ID"));

        mAdapter = new SimpleCursorAdapter(
                this,               
                android.R.layout.simple_list_item_1, 
                null,
                mFromColumns, 
                new int[]{android.R.id.text1},
                0); 
        mCallbacks = this;

        ListView mListView = (ListView) findViewById(R.id.datalist);
        mAdapter.setViewBinder(new ViewBinder());
        mListView.setAdapter(mAdapter);

        getLoaderManager().initLoader(URL_LOADER, null, mCallbacks);
    }

Within the activity I implemented an inner class for die ViewBinder:

private class ViewBinder implements SimpleCursorAdapter.ViewBinder {

        @Override
        public boolean setViewValue(View view, Cursor cursor, int columnIndex) {
            if(view.getId() == R.id.txtV_PhZnr) {
                    TextView phznr = (TextView)view;
                    phznr.setText(cursor.getString(columnIndex));
                    return true;
            }
            return false;
        }

    }

The binding works yet the data is bound to the listview. The other ViewElements stay empty. I can't really understand, why I set the Text of the view "R.id.txtV_PhZnr" and this text appears in the listview-element while the txtV_PhZnr stays empty.

Why do I need a listView-element. As this is a master-detail relationship, only one dataset can be shown in the detail view.

Thank you very much!

Answer 1

Why do I need a listView-element.

No, you do not need one. You can just load the data from your content provider and bind it to the TextView s that you have defined (the ones with ids txtV_xxx ). Do this in the onLoadFinished() method.

I can't really understand, why I set the Text of the view "R.id.txtV_PhZnr" and this text appears in the listview-element while the txtV_PhZnr stays empty.

The view parameter passed to setViewValue() method of ViewBinder will only have one of the ids from the array of view ids that you instantiate the SimpleCursorAdapter with. In your case the view parameter will only have the id android.R.id.text1 since the passed-in array contains only this view id. Thus the body of if(view.getId() == R.id.txtV_PhZnr) {...} will never get executed. Hence txtV_PhZnr stays empty.

ViewBinder is used only when you need to alter the binding of data to views based on some condition. As far as your case goes, there is neither a need for a ListView nor a ViewBinder .