Question

I feel like I’m missing something basic, and I’m actually kind of embarrassed asking this question. But that’s what happens when you start learning a new platform…

I have a ListViewActivity that is populated via a CursorAdapter. When a list item is clicked, I start a new Activity to display the details for that item. What I want to do is enable flinging/swiping to iterate through the items from the detail activity. I don’t want to fully populate a ViewFlipper, as there is no hard-coded limit to the number of items in the List, and it just seems wasteful. Is there some way to intercept the fling gesture/trackball movement, and reset the detail activity with the next/previous item detail?

My ListViewActivity just sets up a Cursor (via managedQuery) and the associated CursorAdapter, with an OnListItemClick that calls startActivity with the appropriate Intent.

public final class ModelList extends ListActivity {

    private Cursor m_models = null;
    private ModelAdapter m_adapter;

    @Override
    public void onCreate (Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if(m_models == null) {
            m_models = managedQuery(Model.CONTENT_URI, Model.PROJECTION, null, null, Model.DEFAULT_SORT_ORDER);
        }
        m_adapter = new ModelAdapter(this, R.layout.modelitem, m_models);
        setContentView(R.layout.forcelist);
        setTitle(R.string.activity_list);
        setListAdapter(m_adapter);
    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        Log.d(getPackageName(), "Clicked item id:" + id);
        if(id < 0) {
            startActivity(new Intent(Intent.ACTION_EDIT, Model.CONTENT_URI));
        } else {
            startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(Model.CONTENT_URI + "/" + id)));
        }
    }
}

My detail Activity seems pretty straightforward; it’s simply a RelativeLayout with a number of Views set up to display the details of the item based on the Intent’s Uri.

public class ModelDetail extends Activity {

    private Uri mUri;
    private FactionHelper factionHelper;
    private static String mCostFormat;
    private static String mDescriptionFormat;
    private ModelAdapter.MarAdapter marAdapter;

    @Override
    public void onCreate (Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.modeldetail);
        setTitle(R.string.activity_detail);
        mCostFormat = getBaseContext().getResources().getString(R.string.modelCostFormat);
        mDescriptionFormat = getBaseContext().getResources().getString(R.string.modelDescriptionFormat);
        mUri = getIntent().getData();
        factionHelper = new FactionHelper(getBaseContext());
        populateData();
    }

    protected void populateData() {

        TextView name = (TextView) findViewById(R.id.modelName);
        TextView description = (TextView) findViewById(R.id.modelDescription);
        // ... More finding Views and populating data ...
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        populateData();
    }

}

Answer 1

Just pass the ID of the current record to the details activity. This will then query the details for the ID given and get a Cursor for that record.

Then create a class which extends ViewSwitcher (the user will only be able to see one details at a time, so we only need 2 views at any one time). In your custom view switcher class add a method similar to:

class MySwitcher extends ViewSwitcher {
    ...

    long currentRowId;
    long nextRowId;
    long previousRowId;

    public void setItemDetails(long rowId) {
        final View nextView = this.getNextView();

        currentRowId = rowId;
        /* Get the next/previous record IDs with a query like
         * "SELECT row_id FROM table WHERE row_id < "+currentRowId+" ORDER BY row_id DESC LIMIT 1;" (Previous)
         * "SELECT row_id FROM table WHERE row_id > "+currentRowId+" ORDER BY row_id ASC LIMIT 1;" (Next)
         */        

        // Do something with nextView, like set some text or something
        // You could get a cursor based on the rowID with
        // "SELECT * FROM table WHERE row_id = "+currentRowId+" LIMIT 1;"
        ((TextView) nextView.findViewById(R.id.myTextView)).setText("Details for item #" + rowId);
        this.showNext();
    }
}

If you don’t want an animation the first time setItemDetails is called then use setAnimateFirstView(false) on the ViewSwitcher.

Then you need to add an OnTouchListener to detect drags/swipes, and then call setItemDetails with the next/previous row ID when you detect a horizontal swipe — you might want to set a different animation depending on whether you are moving to the next or previous item.