Android Swipe Down to Refresh ListView Tutorial

You might have noticed that lot of android apps like Twitter, Google+ provides an option to swipe / pull down to refresh it’s content. Whenever user swipes down from top, a loader will be shown and will disappear once the new content is loaded. In this tutorial we are going to learn how to provide the same option to your apps too.

Previously we used to implement a custom swipe view to detect the swipe down. But android made our day easier by introducing SwipeRefreshLayout in android.support.v4 to detect the vertical swipe on any view.

android-swipe-down-to-refresh-list-view-tutorial

1. Android SwipeRefreshLayout

Implementing SwipeRefreshLayout is very easy. Whenever you want to detect the swipe down on any view, just the wrap the view around SwipeRefreshLayout element. In our case, we are going to use it with ListView. And implement your activity class from SwipeRefreshLayout.OnRefreshListener. When user swipes down the view, onRefresh() method will be triggered. In you need to take appropriate action in that function like making an http call and fetch the latest data.

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

    <!-- place your view here -->

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

2. Example JSON

To demonstrate this tutorial, I am showing IMDB top 250 movies in a List View. For this I have created a json service which gives 20 movies in each request. You need to pass offset param to get the next set of results. Initially offset value should be 0, whenever the list is swiped down, we make an http call to get the next 20 movies and will update the ListView.

URL: http://api.androidhive.info/json/imdb_top_250.php?offset=0

3. Creating Android Project

1. In Android Studio, create a new project by navigating to File ⇒ New Project and fill all the required details. When it prompts to select a default activity, select Blank Activity and proceed.

2. Open build.gradle located under app folder and add volley library dependency. We are going to use volley to make HTTP calls to fetch the json.

com.mcxiaoke.volley:library-aar:1.0.0

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.1.0'
    compile 'com.mcxiaoke.volley:library-aar:1.0.0'
}

3. Open colors.xml under res ⇒ values and add below color resources. If you don’t find colors.xml, create a new file with the name. The color resources added below are used to set background color for movies rank in list view.

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="movie_serial_bg">
        <item>#24c6d5</item>
        <item>#57dd86</item>
        <item>#ad7dcf</item>
        <item>#ff484d</item>
        <item>#fcba59</item>
        <item>#24c6d5</item>
    </string-array>
</resources>

3. Now under your project’s package, create three packages named app, activity and helper.

4. Under app package, create a class named MyApplication.java and add below code. This is a singleton Application class which initiates volley core objects on app launch.

package info.androidhive.swiperefresh.app;

import android.app.Application;
import android.text.TextUtils;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.Volley;

/**
 * Created by Ravi on 13/05/15.
 */

public class MyApplication extends Application {

    public static final String TAG = MyApplication.class
            .getSimpleName();

    private RequestQueue mRequestQueue;

    private static MyApplication mInstance;

    @Override
    public void onCreate() {
        super.onCreate();
        mInstance = this;
    }

    public static synchronized MyApplication getInstance() {
        return mInstance;
    }

    public RequestQueue getRequestQueue() {
        if (mRequestQueue == null) {
            mRequestQueue = Volley.newRequestQueue(getApplicationContext());
        }

        return mRequestQueue;
    }

    public <T> void addToRequestQueue(Request<T> req, String tag) {
        req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
        getRequestQueue().add(req);
    }

    public <T> void addToRequestQueue(Request<T> req) {
        req.setTag(TAG);
        getRequestQueue().add(req);
    }

    public void cancelPendingRequests(Object tag) {
        if (mRequestQueue != null) {
            mRequestQueue.cancelAll(tag);
        }
    }
}

5. Open AndroidManifest.xml and add MyApplication.java class to <application> tag. Also you need to add INTERNET permission as we need to make http calls.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="info.androidhive.swiperefresh">

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:name=".app.MyApplication"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">
        <activity
            android:name=".activity.MainActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

6. Now let’s create a custom adapter class for our list view. Under res ⇒ layout folder, create an xml layout named list_row.xml. This xml renders single list row in the ListView.

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

    <TextView
        android:id="@+id/serial"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="25dp"
        android:layout_margin="5dp"
        android:layout_alignParentLeft="true"
        android:textSize="20dp"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/title"
        android:layout_toRightOf="@id/serial"
        android:layout_centerVertical="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:paddingLeft="20dp"
        android:textSize="18dp" />

</RelativeLayout>

7. Under helper package, create a java class named Movie.java and add below code. This is a model class required to create movie objects to provide data to the List View

package info.androidhive.swiperefresh.helper;

/**
 * Created by Ravi on 13/05/15.
 */
public class Movie {
    public int id;
    public String title;

    public Movie() {
    }

    public Movie(int id, String title) {
        this.title = title;
        this.id = id;
    }
}

8. Under helper package, create another class named SwipeListAdapter.java. This class is a custom adapter class which inflates the list_row.xml by applying proper data.

package info.androidhive.swiperefresh.helper;

import android.app.Activity;
import android.content.Context;
import android.graphics.Color;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import java.util.List;

import info.androidhive.swiperefresh.R;

/**
 * Created by Ravi on 13/05/15.
 */
public class SwipeListAdapter extends BaseAdapter {
    private Activity activity;
    private LayoutInflater inflater;
    private List<Movie> movieList;
    private String[] bgColors;

    public SwipeListAdapter(Activity activity, List<Movie> movieList) {
        this.activity = activity;
        this.movieList = movieList;
        bgColors = activity.getApplicationContext().getResources().getStringArray(R.array.movie_serial_bg);
    }

    @Override
    public int getCount() {
        return movieList.size();
    }

    @Override
    public Object getItem(int location) {
        return movieList.get(location);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        if (inflater == null)
            inflater = (LayoutInflater) activity
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        if (convertView == null)
            convertView = inflater.inflate(R.layout.list_row, null);

        TextView serial = (TextView) convertView.findViewById(R.id.serial);
        TextView title = (TextView) convertView.findViewById(R.id.title);

        serial.setText(String.valueOf(movieList.get(position).id));
        title.setText(movieList.get(position).title);

        String color = bgColors[position % bgColors.length];
        serial.setBackgroundColor(Color.parseColor(color));

        return convertView;
    }

}

10. Now we have all the required files in place, let’s start implementing the actual swipe refresh view. Open the layout file of your main activity (activity_main.xml) and modify the layout as shown below. I have added a ListView to show list of movies and wrapped it around SwipeRefreshLayout to get the swipe to refresh.

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

    <ListView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/listView">

    </ListView>

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

11. Finally open MainActivity.java and do the below changes to achieve the swipe refresh list view.

> Implement the activity from SwipeRefreshLayout.OnRefreshListener and override the onRefresh() method.

> Call fetchMovies() which is a volley’s json array call to fetch the json and update the list view.

> onRefresh() is triggered whenever user swipes down the view. So call fetchMovies() inside this method to get the next set of movies response.

package info.androidhive.swiperefresh.activity;

import android.os.Bundle;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.widget.ListView;
import android.widget.Toast;

import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

import info.androidhive.swiperefresh.R;
import info.androidhive.swiperefresh.app.MyApplication;
import info.androidhive.swiperefresh.helper.Movie;
import info.androidhive.swiperefresh.helper.SwipeListAdapter;


public class MainActivity extends ActionBarActivity implements SwipeRefreshLayout.OnRefreshListener {

    private String TAG = MainActivity.class.getSimpleName();

    private String URL_TOP_250 = "http://api.androidhive.info/json/imdb_top_250.php?offset=";

    private SwipeRefreshLayout swipeRefreshLayout;
    private ListView listView;
    private SwipeListAdapter adapter;
    private List<Movie> movieList;

    // initially offset will be 0, later will be updated while parsing the json
    private int offSet = 0;

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

        listView = (ListView) findViewById(R.id.listView);
        swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_layout);

        movieList = new ArrayList<>();
        adapter = new SwipeListAdapter(this, movieList);
        listView.setAdapter(adapter);

        swipeRefreshLayout.setOnRefreshListener(this);

        /**
         * Showing Swipe Refresh animation on activity create
         * As animation won't start on onCreate, post runnable is used
         */
        swipeRefreshLayout.post(new Runnable() {
                                    @Override
                                    public void run() {
                                        swipeRefreshLayout.setRefreshing(true);

                                        fetchMovies();
                                    }
                                }
        );

    }

    /**
     * This method is called when swipe refresh is pulled down
     */
    @Override
    public void onRefresh() {
        fetchMovies();
    }

    /**
     * Fetching movies json by making http call
     */
    private void fetchMovies() {

        // showing refresh animation before making http call
        swipeRefreshLayout.setRefreshing(true);

        // appending offset to url
        String url = URL_TOP_250 + offSet;

        // Volley's json array request object
        JsonArrayRequest req = new JsonArrayRequest(url,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        Log.d(TAG, response.toString());

                        if (response.length() > 0) {

                            // looping through json and adding to movies list
                            for (int i = 0; i < response.length(); i++) {
                                try {
                                    JSONObject movieObj = response.getJSONObject(i);

                                    int rank = movieObj.getInt("rank");
                                    String title = movieObj.getString("title");

                                    Movie m = new Movie(rank, title);

                                    movieList.add(0, m);

                                    // updating offset value to highest value
                                    if (rank >= offSet)
                                        offSet = rank;

                                } catch (JSONException e) {
                                    Log.e(TAG, "JSON Parsing error: " + e.getMessage());
                                }
                            }

                            adapter.notifyDataSetChanged();
                        }

                        // stopping swipe refresh
                        swipeRefreshLayout.setRefreshing(false);

                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.e(TAG, "Server Error: " + error.getMessage());

                Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show();

                // stopping swipe refresh
                swipeRefreshLayout.setRefreshing(false);
            }
        });

        // Adding request to request queue
        MyApplication.getInstance().addToRequestQueue(req);
    }

}

Run the project and test it. You should able see the swipe refresh animation on app launch and list view updated each time you swipe down it.

android swipe down to refresh listview

4. PHP Class to Generate JSON

As lot of people are requesting me to provide the PHP code to generate the json, I am giving the code to generate the json used in this article. You can run this code using WAMP or XAMP softwares. Checkout Video 1 and Video 2 for installation and running PHP project in WAMP.

<?php

// sleep for 2 sec show that the androd swipe refresh will be visible for sometime
sleep(2);

// all top 250 movies
$movies = array("The Shawshank Redemption", "The Godfather", "The Godfather: Part II", "The Dark Knight", "Pulp Fiction", "Schindler's List", "12 Angry Men", "The Good, the Bad and the Ugly", "The Lord of the Rings: The Return of the King", "Fight Club", "The Lord of the Rings: The Fellowship of the Ring", "Star Wars: Episode V - The Empire Strikes Back", "Forrest Gump", "Inception", "One Flew Over the Cuckoo's Nest", "The Lord of the Rings: The Two Towers", "Goodfellas", "The Matrix", "Star Wars", "Seven Samurai", "City of God", "Se7en", "The Usual Suspects", "The Silence of the Lambs", "It's a Wonderful Life", "Interstellar", "Léon: The Professional", "Life Is Beautiful", "Once Upon a Time in the West", "Casablanca", "American History X", "Saving Private Ryan", "Spirited Away", "Raiders of the Lost Ark", "City Lights", "Psycho", "Rear Window", "The Intouchables", "Whiplash", "Modern Times", "The Green Mile", "Terminator 2: Judgment Day", "Memento", "The Pianist", "The Departed", "Apocalypse Now", "Gladiator", "Sunset Blvd.", "Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb", "Back to the Future", "Alien", "The Prestige", "The Lion King", "The Great Dictator", "The Lives of Others", "Cinema Paradiso", "Django Unchained", "The Shining", "Paths of Glory", "The Dark Knight Rises", "American Beauty", "WALL·E", "North by Northwest", "Aliens", "Citizen Kane", "Grave of the Fireflies", "Vertigo", "M", "Oldboy", "Das Boot", "Amélie", "Princess Mononoke", "Star Wars: Episode VI - Return of the Jedi", "Once Upon a Time in America", "Toy Story 3", "Reservoir Dogs", "A Clockwork Orange", "Braveheart", "Taxi Driver", "Double Indemnity", "Witness for the Prosecution", "Requiem for a Dream", "To Kill a Mockingbird", "Lawrence of Arabia", "Eternal Sunshine of the Spotless Mind", "Full Metal Jacket", "Bicycle Thieves", "The Sting", "Singin' in the Rain", "Amadeus", "Monty Python and the Holy Grail", "Snatch.", "2001: A Space Odyssey", "For a Few Dollars More", "Rashomon", "L.A. Confidential", "The Kid", "All About Eve", "The Apartment", "Inglourious Basterds", "Toy Story", "The Treasure of the Sierra Madre", "A Separation", "Indiana Jones and the Last Crusade", "Yojimbo", "The Third Man", "Some Like It Hot", "Metropolis", "Batman Begins", "Unforgiven", "Scarface", "Like Stars on Earth", "Raging Bull", "Up", "3 Idiots", "Downfall", "Chinatown", "The Great Escape", "Die Hard", "The Hunt", "On the Waterfront", "Heat", "Mr. Smith Goes to Washington", "Pan's Labyrinth", "Good Will Hunting", "The Bridge on the River Kwai", "My Neighbor Totoro", "Ikiru", "The Seventh Seal", "The Gold Rush", "Ran", "Wild Strawberries", "The General", "Blade Runner", "The Elephant Man", "Lock, Stock and Two Smoking Barrels", "The Secret in Their Eyes", "The Wolf of Wall Street", "Casino", "Gran Torino", "Howl's Moving Castle", "Warrior", "The Big Lebowski", "V for Vendetta", "Rebecca", "The Bandit", "Gone Girl", "The Deer Hunter", "Judgment at Nuremberg", "Cool Hand Luke", "How to Train Your Dragon", "It Happened One Night", "Fargo", "A Beautiful Mind", "Gone with the Wind", "Trainspotting", "Into the Wild", "Rush", "Dial M for Murder", "The Maltese Falcon", "The Sixth Sense", "Mary and Max", "Finding Nemo", "The Thing", "The Wages of Fear", "Hotel Rwanda", "No Country for Old Men", "Incendies", "Rang De Basanti", "Kill Bill: Vol. 1", "Platoon", "Life of Brian", "Butch Cassidy and the Sundance Kid", "Network", "A Wednesday", "Munna Bhai M.B.B.S.", "Touch of Evil", "There Will Be Blood", "12 Years a Slave", "Annie Hall", "The 400 Blows", "Stand by Me", "The Princess Bride", "Persona", "The Grand Budapest Hotel", "Amores Perros", "Ben-Hur", "Diabolique", "In the Name of the Father", "The Grapes of Wrath", "Million Dollar Baby", "Sin City", "Hachi: A Dog's Tale", "Nausicaä of the Valley of the Wind", "The Wizard of Oz", "The Best Years of Our Lives", "Gandhi", "The Avengers", "The Bourne Ultimatum", "Donnie Darko", "Shutter Island", "Stalker", "8½", "Guardians of the Galaxy", "Strangers on a Train", "Infernal Affairs", "Twelve Monkeys", "Fanny and Alexander", "Before Sunrise", "Boyhood", "Jaws", "The Imitation Game", "The Battle of Algiers", "The Terminator", "High Noon", "Groundhog Day", "Harry Potter and the Deathly Hallows: Part 2", "Memories of Murder", "The King's Speech", "Ip Man", "Monsters, Inc.", "Notorious", "Rocky", "Dog Day Afternoon", "Barry Lyndon", "La Haine", "The Truman Show", "Who's Afraid of Virginia Woolf?", "A Fistful of Dollars", "Dil Chahta Hai", "The Night of the Hunter", "Pirates of the Caribbean: The Curse of the Black Pearl", "Lagaan: Once Upon a Time in India", "Castle in the Sky", "Jurassic Park", "X-Men: Days of Future Past", "La Strada", "The Help", "Roman Holiday", "Wild Tales", "The Big Sleep", "Spring, Summer, Fall, Winter... and Spring", "Le Samouraï", "Prisoners", "Underground", "The Graduate", "Paris, Texas", "Solaris", "Three Colors: Red", "Papillon");

// reading offset from get parameter
$offset = isset($_GET['offset']) && $_GET['offset'] != '' ? $_GET['offset'] : 0;

// page limit
$limit = 20;


$movies_array = array();

// loop through page movies
for ($j = $offset; $j < $offset + $limit && $j < sizeof($movies); $j++) {
    $tmp = array();
    $tmp['rank'] = $j + 1;
    $tmp['title'] = $movies[$j];

    array_push($movies_array, $tmp);
}

// printing json response
echo json_encode($movies_array);
?>
Ravi is hardcore Android programmer and Android programming has been his passion since he compiled his first hello-world program. Solving real problems of Android developers through tutorials has always been interesting part for him.