Filtering List with Search Manager in Connfa Android App

It is a good practice to provide the facility to filter lists in Android apps to improve the user experience. It often becomes very unpleasing to scroll through the entire list when you want to reach a certain data point. Recently I modified Connfa app to read the list of speakers from the Open Event Format. In this blog I describe how to add filtering facility in lists with Search Manager.

First, we declare the search menu so that the widget appears in it.

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/search"
        android:title="Search"
        android:icon="@drawable/search"
        android:showAsAction="collapseActionView ifRoom"
        android:actionViewClass="android.widget.SearchView" />
</menu>

In above menu item the collapseActionView attribute allows your SearchView to expand to take up the whole action bar and collapse back down into a normal action bar item when not in use. Now we create the SearchableConfiguration which defines how SearchView behaves.

<?xml version="1.0" encoding="utf-8"?>
<searchable
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:label="@string/app_name"
    android:hint="Search friend">
</searchable>

Also add this to the activity that will be used with <meta-data> tag in the manifest file. Then associate searchable configuration with the SearchView in the activity class

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.search_menu, menu);

    SearchManager searchManager = (SearchManager)
                            getSystemService(Context.SEARCH_SERVICE);
    searchMenuItem = menu.findItem(R.id.search);
    searchView = (SearchView) searchMenuItem.getActionView();

    searchView.setSearchableInfo(searchManager.
                            getSearchableInfo(getComponentName()));
    searchView.setSubmitButtonEnabled(true);
    searchView.setOnQueryTextListener(this);

    return true;
}

Implement SearchView.OnQueryTextListener in activity, need to override two new methods now

@Override
public boolean onQueryTextSubmit(String searchText) {
  
  return true;
}

@Override
public boolean onQueryTextChange(String searchedText) {

   if (mSpeakersAdapter != null) {
       lastSearchRequest = searchedText;
       mSpeakersAdapter.getFilter().filter(searchedText);
   }
   return true;
}

Find the complete implementation here. In the end it will look like this,

 

References

Android Search View documentation – https://developer.android.com/reference/android/widget/SearchView.html

Using Data Access Object to Store Information

We often need to store the information received from the network to retrieve that later. Although we can store and read data directly but by using data access object to store information enables us to do data operations without exposing details of the database. Using data access object is also a best practice in software engineering. Recently I modified Connfa app to store the data received in Open Event format. In this blog, I describe how to use data access object.

The goal is to abstract and encapsulate all access to the data and provide an interface. This is called Data Access Object pattern. In a nutshell, the DAO “knows” which data source (that could be a database, a flat file or even a WebService) to connect to and is specific for this data source. It makes no difference in applications when it accesses a relational database or parses xml files (using a DAO). The DAO is usually able to create an instance of a data object (“to read data”) and also to persist data (“to save data”) to the datasource.

Consider the example from Connfa app in which get the tracks from API and store them in SQL database. We use DAO to create a layer between model and database. Where AbstractEntityDAO is an abstract class which have the functions to perform CRUD operation. We extend it to implement them in our DAO model. Here is TrackDAO structure,

public class TrackDao extends AbstractEntityDAO<Track, Long> {

    public static final String TABLE_NAME = "table_track";

 [email protected]
    protected String getSearchCondition() {
        return "_id=?";
    }
    
    ...
}

Find the complete class to see the detailed methods to implement search conditions, get key columns, create instance etc.  here.

Here is a general method to get the data from the database. Where getFacade() for the given layer element, this method returns the requested facade object to represent the passed in layer element.

public List<ClassToSave> getAllSafe() {
   ILAPIDBFacade facade = getFacade();
   try {
       facade.open();
       return getAll();

   } finally {
       facade.close();
   }
}

Now we can create an instance to use these methods instead of directly using SQL operations. This functions gets the data and sort it accordingly.

private TrackDao mTrackDao;
 public List<Track> getTracks() {
   List<Track> tracks = mTrackDao.getAllSafe();
   Collections.sort(tracks, new Comparator<Track>() {
 [email protected]
       public int compare(Track track, Track track2) {
           return Double.compare(track.getOrder(), track2.getOrder());
       }
   });
   return tracks;
}

References:

 

Receiving Data From the Network Asynchronously

We often need to receive information from networks in Android apps. Although it is a simple process but the problem arises when it is done through the main user interaction thread. To understand this problem better consider using an app which shows some text downloaded from the online database. As the user clicks a button to display a text it may take some time to get the HTTP response. So what does an activity do in that time? It creates a lag in the user interface and makes the app to stop responding. Recently I implemented this in Connfa App to download data in Open Event Format.

To solve that problem we use concurrent thread to download the data and send the result back to be processed separating it from main user interaction thread. AsyncTask allows you to perform background operations and publish results on the UI thread without having to manipulate threads and/or handlers.

AsyncTask is designed to be a helper class around Thread and Handler and does not constitute a generic threading framework. AsyncTasks should ideally be used for short operations (a few seconds at the most). If you need to keep threads running for long periods of time, it is highly recommended you use the various APIs provided by the java.util.concurrent package such as Executor, ThreadPoolExecutor and FutureTask.

An asynchronous task is defined by a computation that runs on a background thread and whose result is published on the UI thread. An asynchronous task is defined by 3 generic types, called Params, Progress and Result, and 4 steps, called onPreExecute, doInBackground, onProgressUpdate and onPostExecute.

In this blog, I describe how to download data in an android app with AsyncTask using OkHttp library.

First, you need to add dependency for OkHttp Library,

compile 'com.squareup.okhttp:okhttp:2.4.0' 


Extend AsyncTask class and implement all the functions in the class by overriding them to modify them accordingly. Here I declare a class named AsyncDownloader extending AsyncTask. We took the string parameter, integer type progress and string type result to return instead which will be our JSON data and param is our URL. Instead of using get the function of AsyncTask we implement an interface to receive data so the main user interaction thread does not have to wait for the return of the result.

public class AsyncDownloader extends AsyncTask<String, Integer, String> {
    private String jsonData = null;

    public interface JsonDataSetter {
        void setJsonData(String str);
    }


    JsonDataSetter jsonDataSetterListener;

    public AsyncDownloader(JsonDataSetter context) {

        this.jsonDataSetterListener = context;
    }

 [email protected]
    protected void onPreExecute() {
        super.onPreExecute();
    }

 [email protected]
    protected String doInBackground(String... params) {

        String url = params[0];

        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(url)
                .build();
        Call call = client.newCall(request);

        Response response = null;

        try {
            response = call.execute();

            if (response.isSuccessful()) {
                jsonData = response.body().string();

            } else {
                jsonData = null;
            }

        } catch (IOException e) {
            e.printStackTrace();
        }


        return jsonData;
    }

 [email protected]
    protected void onPostExecute(String jsonData) {
        super.onPostExecute(jsonData);
        jsonDataSetterListener.setJsonData(jsonData);
    }
}


We download the data in doInBackground making a request using OkHttp library and send the result back in onPostExecute method using our interface method. See above to check out the complete class implementation.

You can make an instance to AsyncDownloader in an activity. Implement interface to receive that data.

Tip: Always close AsyncTask after using to avoid many concurrent tasks at one time.

Find the complete code here.

References:

Advantage of Open Event Format over xCal, pentabarf/frab XML and iCal

Event apps like Giggity and Giraffe use event formats like xCal, pentabarf/frab XML, iCal etc. In this blog, I present some of the advantages of using FOSSASIA’s Open Event data format over other formats. I added support for Open Event format in these two apps so I describe the advantages and improvements that were made with respect to them.

  • The main problem that is faced in Giggity app is that all the data like social links, microlocations, the link for the logo file etc., can not be fetched from a single file, so a separate raw file is being added to provide this data. Our Open Event format provides all this information from the single URL that could be received from the server so no need to use any separate file.
  • Here is the pentabarf format data for FOSSASIA 2016 conference excluding sessions. Although it provides all the necessary information it leaves the information for logo URL, details for longitude and latitude for microlocations (rooms) and links to social media and website. While the open event format provides all the missing details including some extra information like language, comments etc. See FOSSASIA 2016 Open Event format sample.
<conference>
<title>FOSSASIA 2016</title>
<subtitle/>
<venue>Science Centre Road</venue>
<city>Singapore</city>
<start>2016-03-18</start>
<end>2016-03-20</end>
<days>3</days>
<day_change>09:00:00</day_change>
<timeslot_duration>00:00:00</timeslot_duration>
</conference>
  • The parsing of received file format gets very complicated in case of iCal, xCal etc. as tags needs to be matched to get the data. Howsoever there are various libraries available for parsing JSON data. So we can create simply an array list of the received data to send it to the adapter. See this example for more information of working code. You can also see the parser for iCal to compare the complexity of the code.
  • The other more common problem is the structure of the formats received is sometimes it becomes complicated to define the sub parts of a single element. For example for the location we define latitude and longitude separately while in iCal format it is just separated by a comma. For example for

iCal

GEO:1.333194;103.736132

JSON

{
           "id": 1,
           "name": "Stage 1",
           "floor": 0,
           "latitude": 37.425420,
           "longitude": -122.080291,
           "room": null
}

And the information provided is more detailed.

  • Open Event format is well documented and it makes it easier for other developers to work on it. Find the documentation here.

References:

 

Displaying Multiple Markers on Map

Connfa and Open Event Android app provide the facility to see the locations on Google map by displaying the marker on places where the sessions will be taking place. As there are many sessions in a conference we need to display marker for each location. In this blog, we learn how to display multiple markers on a map using Google map API with the reference of Connfa app.
First, you need to set up the Google map API in your app. Find the detailed tutorial for that here where you can follow to get an API key and you’ll need a Gmail account for that. Then you can define a fragment like this in your XML layout where the map will appear.

<FrameLayout
   android:id="@+id/fragmentHolder"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:layout_below="@+id/layoutInfo"
   android:background="@android:color/white" />

Now you can define the in the fragment to make map in this FrameLayout named “fragmentHolder”,

private void replaceMapFragment() {
   CustomMapFragment mapFragment = CustomMapFragment.newInstance(LocationFragment.this);
   LocationFragment
           .this.getChildFragmentManager()
           .beginTransaction()
           .replace(R.id.fragmentHolder, mapFragment)
           .commitAllowingStateLoss();
}

We receive the data about locations in a List containing longitude, latitude, name and room number of the locations. Find the sample result in Open Event format. Here is how we fill in the locations,

for (int i = 0; i < locations.size(); i++) {
   Location location = locations.get(i);
   LatLng position = new LatLng(location.getLat(), location.getLon());
   mGoogleMap.addMarker(new MarkerOptions().position(position));

   if (i == 0) {
       CameraPosition camPos = new CameraPosition(position, ZOOM_LEVEL, TILT_LEVEL, BEARING_LEVEL);
       mGoogleMap.moveCamera(CameraUpdateFactory.newCameraPosition(camPos));
       fillTextViews(location);
   }
}

The CameraPostition defines the properties like Zoom level which can be adjusted by changing the parameters. You can define the like this,

private static final int ZOOM_LEVEL = 15;
private static final int TILT_LEVEL = 0;
private static final int BEARING_LEVEL = 0;

Find the complete implementation here. Here is the screenshot for the final result.

References:

  • Google Map APIs Documentation – https://developers.google.com/maps/documentation/android-api/map-with-marker

Checking Image Size to Avoid Crash in Android Apps

In Giggity app a user can create a shortcut for the event by clicking on “home shortcut” button in the navigation drawer. Open Event format provides the logo URL in the return data so we do not need to provide it separately in the app’s raw file.

Sometimes the image can be too big to be put on screen as icon for shortcut. In this blog I describe a very simple method to check if we should use the image or not to avoid the crash and pixelation due to resolution.

We can store the image received in bitmap format. A bitmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits, a spatially mapped array of bits. By storing it in bitmap format we can easily get the necessary information about the image to check if it is suitable for use.

We can use the BitmapFactory class which provides several decoding methods like (decodeByteArray(), decodeFile(), decodeResource(), etc.) for creating a Bitmap from various sources. Choose the most appropriate decode method based on your image data source. These methods attempt to allocate memory for the constructed bitmap and therefore can easily result in an OutOfMemory exception. Each type of decode method has additional signatures that let you specify decoding options via the BitmapFactory.Options class. Setting the inJustDecodeBounds property to true while decoding avoids memory allocation, returning null for the bitmap object but setting outWidth, outHeight and outMimeType. This technique allows you to read the dimensions and type of the image data prior to construction (and memory allocation) of the bitmap.

BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.id.myimage, options);
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;
String imageType = options.outMimeType;

To avoid java.lang.OutOfMemory exceptions, check the dimensions of a bitmap before decoding it, unless you absolutely trust the source to provide you with predictably sized image data that comfortably fits within the available memory.

So here is the particular example from Giggity app, it avoids crash on the recieving a large image for the icon. So once we store the the image in bitmap format we check if the height and width of the icon is exceeding the maximum limit.

public Bitmap getIconBitmap() {

 InputStream stream = getIconStream();
 Bitmap ret = null;

 if (stream != null) {
 ret = BitmapFactory.decodeStream(stream);
 if (ret == null) {
 Log.w("getIconBitmap", "Discarding unparseable file");
 return null;
 }
 if (ret.getHeight() > 512 || ret.getHeight() != ret.getWidth()) {
 Log.w("getIconBitmap", "Discarding, icon not square or >512 pixels");
 return null;
 }
 if (!ret.hasAlpha()) {
 Log.w("getIconBitmap", "Discarding, no alpha layer");
 return null;
 }
 }
 
 return ret;
}

If it does then we can avoid the icon. In this case we check if the icon is more than 512 pixels in height and width. If it is so then we could avoid it.

We could also check if the icon has a transparent background by using “hasAlpha” so we could have uniformity in the icons displayed on the screen. In the final result you can see the icon of the TUBIX 2017 conference added on the screen as it was following all those defined criterias.

Now that the image dimensions are known, they can be used to decide if the full image should be loaded into memory or if a subsampled version should be loaded instead. Here are some factors to consider:

  • Estimated memory usage of loading the full image in memory.
  • Amount of memory you are willing to commit to loading this image given any other memory requirements of your application.
  • Dimensions of the target ImageView or UI component that the image is to be loaded into.
  • Screen size and density of the current device.

For example, it’s not worth loading a 1024×768 pixel image into memory if it will eventually be displayed in a 128×96 pixel thumbnail in an ImageView.

 

References:

Upgrading the Style and Aesthetic of an Android App using Material Design

I often encounter apps as I add Open Event format support that don’t follow current design guidelines. Earlier styling an app was a tough task as the color and behaviour of the views needed to be defined separately. But now as we move forward to advanced styling methods we can easily style our app.

I recently worked on upgrading the user interface of Giraffe app after adding our Open Event support. See the repository to view the code for more reference. Here I follow the same procedure to upgrade the user interface.

First we add essential libraries to move with our material aesthetic. The Appcompat library provides backward compatibility.

//Essential Google libraries
compile 'com.android.support:appcompat-v7:25.3.1'
compile 'com.android.support:design:25.3.1

Then we define an XML file in the values folder for the style of the app which we get through Appcompat library. We could inherit same style in the entire app or separate style for the particular activity.

<resources>

   <!-- Base application theme. -->
   <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
       <!-- Customize your theme here. -->
       <item name="colorPrimary">@color/colorPrimary</item>
       <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
       <item name="colorAccent">@color/colorAccent</item>
   </style>


   <style name="AlertDialogCustom" parent="Theme.AppCompat.Light.Dialog.Alert">
       <item name="colorPrimary">@color/colorPrimary</item>
       <item name="colorAccent">@color/colorAccent</item>
   </style>

</resources>

So now we can see the views made following the same color scheme and behaviour throughout the app following current design guidelines without any particular manipulation to each of them.

Tip: Don’t define values of colors separately for different views. Define them in colors.xml to use them everywhere. It becomes easier then to change in future if needed.

The app now uses Action Bar for the frequently used operations unlike the custom layout that was made earlier.

This is how Action Bar is implemented,

First declare the action bar in XML layout,

Tip: Define color of the bar two shades lighter than the status bar.

 <android.support.design.widget.AppBarLayout
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:background="@android:color/transparent"
             android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
             <android.support.v7.widget.Toolbar

                 xmlns:app="http://schemas.android.com/apk/res-auto"         
                 android:id="@+id/toolbar_options"
                 android:layout_width="match_parent"
                 android:layout_height="?attr/actionBarSize"
                 android:background="@color/colorPrimary"
                 app:popupTheme="@style/ThemeOverlay.AppCompat.Dark">
                 
                 <TextView
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:text="@string/options"
                     android:textColor="@color/colorAccent"
                     android:textSize="20sp" />
              </android.support.v7.widget.Toolbar>

</android.support.design.widget.AppBarLayout>

Then you can use the action bar in the activity, use onCreateOptionsMenu() method to inflate options in the toolbar.

@Override
    public void onCreate(Bundle savedInstanceState) {
        ...

        setTitle("");
        title = (TextView) findViewById(R.id.titlebar);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar_main);
        setSupportActionBar(toolbar);

        ...
    }

The menu that needs to be inflated will be like this for two button at the right end of the action bar for bookmarks and filter respectively,

<menu xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto">
     <item
        android:id = "@+id/action_bookmark"
        android:icon = "@drawable/ic_bookmark"
        android:menuCategory = "secondary"
        android:title = "Bookmark"
        app:showAsAction = "ifRoom" />
 
     <item
         android:id = "@+id/action_filter"
         android:icon = "@drawable/ic_filter"
         android:menuCategory = "secondary"
         android:title = "Filter"
         app:showAsAction = "ifRoom" />
</menu>

To adapt the declared style further, Alert Dialogs are also modified to match the app’s theme, it’s style is defined along with the app’s style. See below

AlertDialog.Builder noFeedBuilder = new AlertDialog.Builder(context,R.style.AlertDialogCustom);
            noFeedBuilder.setMessage(R.string.main_no_feed_text)
                    .setTitle(R.string.main_no_feed_title)
                    .setPositiveButton(R.string.common_yes, new DialogInterface.OnClickListener() {
                  ...
            noFeedBuilder.show();

Here is an example of improvement, before and after we update the user interface and aesthetic of app in easy steps defined,

   

See this for all the changes made to step up the user interface of the app.

References:

 

Importing the Open Event format in Giraffe

Giraffe is a personal conference schedule tool for Android. Most conferences, bar camps and similar events offer their plan of sessions and talks in the iCal format for importing into your calendar. However importing a whole session plan into your standard calendar renders it pretty much useless for anything else. Giraffe allows users to import the schedule into a separate list giving you a simple overview on what happens on the conference. Besides the session, title, date and  time it also lists the speaker, location and description if available in the iCal URL. Sessions can be bookmarked and the list can be filtered by favourites and upcoming talks.

Recently I added the support for Open Event JSON format along with iCal. In this blog I describe the simple steps you need to follow to see the event that is created in the Open Event server in the Giraffe app. The initial steps are similar to Giggity app,

 1. Go to your event dashboard

2. Click on the export button.

3. Select sessions from the dashboard and copy the URL.

 

4. Click on the “Giraffe” button on the toolbar and paste the link in the box following. App will ask you to paste it when the first time you open it. Here the app loads the data and checks few initial character to see which kind of data is received. Find my other blog post to solve that problem here.

The app uses separate data models for iCal and JSON to store the informations received and then save them in SQL database for CRUD options. See the database activity here

   

5. Now you can see the sessions. Click on them to see more information or bookmark them if needed. The data is loaded from the database so when app is offline so we don’t need to worry about connection once the data is being loaded.

   

Resources:

 

Viewing an Event in Giggity

Giggity is an Android app that loads xCal, pentabarf, frab, wafer and iCal files (that contain schedules of conferences, festivals and other events) and lets you browse them in various convenient formats. It is a generic app that can be used for any event that publishes their schedule in an open format. Recently support to see Open Event JSON format has been added in the Giggity. In this blog I describe the simple steps you need to follow to see the event that is created in the Open Event server and can be seen in the Giggity app. Although the process of creating an event is quite detailed but the UI is very user friendly and simple to use so here I describe the process after creating the event and adding it in Giggity app

1. Go to your event dashboard

2. Click on the export button

3. Select sessions and microlocations by clicking the switch buttons. Get the url generated and copy it. Skipping the microlocations will disable the option to navigate to the location in map opening from the app.

4. Click on the “+” button on the toolbar and paste the link.

   

5. Now you can see the sessions with locations. Slide the navigation drawer to see the links and signup url or create the home screen shortcut.

   

So here you can see your event following these five simple steps. Watch this video to see this in action.

https://www.youtube.com/watch?v=RairLTXqqDI

Differentiating between received file formats for Event Apps

Sometimes we need to operate on files of different formats in the same app itself for example Giggity app parses the file in iCal, xCal, pentabarf and now in Open Event JSON format.

It could be problematic as every format needs different type of manipulation to read and get the relevant data from it, for example the JSON format is based on objects and arrays in it from which we can get the data by referencing titles of the data while pentabarf XML identifies the elements with tags. Also it is not evident from the link itself which format is being received. So to see which type of file is received instead of analyzing the entire file we look for the few initials of the syntax from which it becomes evident.

I recently used this method to differentiate between the JSON and iCal format to display sessions of an event in the Giraffe app in Open Event JSON format which is also being used in Giggity.

Let’s have a look on how to actually implement this. It is simple after you get the data from the url. Instead of iterating for the entire data we read the initial data only to see what kind of file we have received.

BufferedReader r = new BufferedReader(new InputStreamReader(inputStream));
String line = r.readLine();

if(line.contains("BEGIN:VCALENDAR")) {
 SharedPreferences.Editor edit = prefs.edit();
 edit.putString("type", "ical");
 edit.commit();
 Log.e("Response type","ical");
} 
else if(line.contains("{")) {
 SharedPreferences.Editor edit = prefs.edit();
 edit.putString("type", "json");
 edit.commit();
 Log.e("Response type","json");
}

We saved the type of response received in the shared preferences so we retrieve it later from anywhere in the app to see what kind of data we have received instead of passing it in between functions or activities.

See this to check as you download the data from the URL asynchronously, so you don’t need to do it later or manipulations needs to be done asynchronously too.

So when you are checking in asynchronously using AsyncTask class get shared preferences in onPreExecute() and update it in doInBackground() as we download the data and check.

The other advantage of this method is that we can close the thread or return to the main activity if the file format found is not readable or not of desired format.