Friday, June 20, 2014

Easy Swipe to Refresh in Android

Swipe to Refresh Android
Recently, Google released a new version of the Support Library, which has an interesting component. It's called SwipeRefreshLayout. With that, it's become a child's play to implement a quick Swipe-to-Refresh control for your apps.

A few things first

  1. Available only with android-support-v13. Which means that only apps target SDK level 13 and above can use this.
  2. It can only contain one scrollable direct child such as a ListView or a ScrollView.
That's all you need to know. Well.. A few things more, basically some xml and java code.

For this example, we use a ListView with some demo data. Once the list view is scrolled, we do some task, wait for sometime, and update the list view's adapter. Finally, ask the SwipeRefreshLayout to stop the progress indicator, since we are done with refreshing.

The layout file
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${packageName}.${activityClass}" >
    <android.support.v4.widget.SwipeRefreshLayout
        android:id="@+id/swipeLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
        <ListView
            android:id="@+id/listView"
            android:layout_width="match_parent"
            android:layout_height="match_parent" >
        </ListView>
    </android.support.v4.widget.SwipeRefreshLayout>
</RelativeLayout>
The UI initialization
private void initializeViews() {
refreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipeLayout);
refreshLayout.setOnRefreshListener(this);
                // The default colors for the progress bar are not so nice.
setColorSchemeForProgressBar();
ListView listView = (ListView) findViewById(R.id.listView);
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1);
adapter.addAll(getDemoData(5));
listView.setAdapter(adapter);
  }
The Refresh Task
       @Override
public void onRefresh() {
Log.i(TAG, "Refresh Requested");
doRefresh();
}
// Fetch data and update listview's adapter
private void doRefresh() {
RefreshTask task = new RefreshTask();
task.execute((Void) null);
The Completion Work
private void postRefreshComplete() {
// Stop the refresh animation
refreshLayout.setRefreshing(false);
// Update adapter with new data
adapter.clear();
adapter.addAll(getDemoData(new Random().nextInt(20)));
adapter.notifyDataSetChanged();
   }

And there you go, a simple swipe to refresh usage for your Android apps. You can find the whole source code here