Implementing Pull to Refresh Guide

Overview

In Android, the common "pull to refresh" UX concept is not built in to a ListView. However, many Android applications would like to make use of this concept for their feeds. This is useful for all sorts of feeds such as a Twitter timeline. This effect can be achieved using either the SwipeRefreshLayout from the support library, which was recently introduced and back-ported to all versions down to Android API level 4.

Using SwipeRefreshLayout

SwipeRefreshLayout is a ViewGroup that can hold only one scrollable view as a child. This can be either a ScrollView or an AdapterView such as a ListView.

Note: This layout only exists within more recent versions of support-v4 as explained in this post. Edit your app/build.gradle file to include a support library later than version 19:

apply plugin: 'com.android.application'

//...

dependencies {
    // ...
    compile 'com.android.support:support-v4:22.2.0'
}

You must download and use a recent jar of the support library for this to work or install the support library via the Android Studio SDK Manager:

1. Open the SDK Manager from Android Studio with Tools -> Android -> SDK Manager
2. The support library is under "Extras"

Once you have a recent version support library installed, we can continue.

Step 1: Wrap ListView

We can use this by first wrapping the scrollable view with a SwipeRefreshLayout in the XML layout:

<android.support.v4.widget.SwipeRefreshLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/swipeContainer"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

  <ListView
      android:id="@+id/lvItems"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_alignParentLeft="true"
      android:layout_alignParentTop="true" >
  </ListView>

</android.support.v4.widget.SwipeRefreshLayout>

Step 2: Setup SwipeRefreshLayout

Next, we need to configure the SwipeRefreshLayout during view initialization in the activity:

public class TimelineActivity extends Activity {
    private SwipeRefreshLayout swipeContainer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        swipeContainer = (SwipeRefreshLayout) findViewById(R.id.swipeContainer);
        // Setup refresh listener which triggers new data loading
        swipeContainer.setOnRefreshListener(new OnRefreshListener() {
            @Override
            public void onRefresh() {
                // Your code to refresh the list here.
                // Make sure you call swipeContainer.setRefreshing(false)
                // once the network request has completed successfully.
                fetchTimelineAsync(0);
            } 
        });
        // Configure the refreshing colors
        swipeContainer.setColorSchemeResources(android.R.color.holo_blue_bright, 
                android.R.color.holo_green_light, 
                android.R.color.holo_orange_light, 
                android.R.color.holo_red_light);
    }

    public void fetchTimelineAsync(int page) {
        client.getHomeTimeline(0, new JsonHttpResponseHandler() {
            public void onSuccess(JSONArray json) {
                // Remember to CLEAR OUT old items before appending in the new ones
                adapter.clear();
                // ...the data has come back, add new items to your adapter...
                adapter.addAll(...);
                // Now we call setRefreshing(false) to signal refresh has finished
                swipeContainer.setRefreshing(false);
            }

            public void onFailure(Throwable e) {
                Log.d("DEBUG", "Fetch timeline error: " + e.toString());
            }
        });
    }
}

Note that upon successful reload, we must also signal that the refresh has completed by calling setRefreshing(false). Also note that you should clear out old items before appending the new ones during a refresh.

References

• http://antonioleiva.com/swiperefreshlayout/