Using Multiple Languages in Giggity app

Giggity app is used for conferences around the world. It becomes essential that it provides support for native languages as the users may not understand the terminologies written primarily in English from different countries. In this blog, I describe how to add a resource for another language in your app with the example of Giggity.  I recently worked on the addition of French translation in the app. We look at the addition of German in the app.

You can specify resources tailored to the culture of the people who use your app. You can provide any resource type that is appropriate for the language and culture of your users. For example, the following screenshot shows an app displaying string and drawable resources in the device’s default (en_US) locale and the German (de_DE) locale.

It is good practice to use the Android resource framework to separate the localized aspects of your application as much as possible from the core Java functionality:

  • You can put most or all of the contents of your application’s user interface into resource files, as described in this document and in Providing Resources.
  • The behaviour of the user interface, on the other hand, is driven by your Java code. For example, if users input data that needs to be formatted or sorted differently depending on locale, then you would use Java to handle the data programmatically. This document does not cover how to localize your Java code.

Whenever the application runs in a locale for which you have not provided locale-specific text, Android will load the default strings from res/values/strings.xml. If this default file is absent, or if it is missing a string that your application needs, then your application will not run and will show an error. Here is an example of default strings in the app.

<!-- Menu -->
<string name="settings">Settings</string>
<string name="change_day">Change day</string>
<string name="show_hidden">Show hidden items</string>
<string name="timetable">Timetable</string>
<string name="tracks">Tracks</string>
<string name="now_next">Now and next</string>
<string name="my_events">My events</string>
<string name="search">Search</string>

An application can specify many res/<qualifiers>/ directories, each with different qualifiers. To create an alternative resource for a different locale, you use a qualifier that specifies a language or a language-region combination. (The name of a resource directory must conform to the naming scheme described in Providing Alternative Resources, or else it will not compile.) You can specify resources tailored to the culture of the people who use your app. You can provide any resource type that is appropriate for the language and culture of your users. For example, the following screenshot shows an app displaying string and drawable resources in the device’s default (en_US) locale and the German (de_DE) locale.

<!-- Menu -->
<string name="settings">Einstellungen</string>
<string name="change_day">Tag ändern</string>
<string name="timetable">Zeitplan</string>
<string name="tracks">Tracks</string>
<string name="now_next">Jetzt und gleich</string>
<string name="my_events">Meine Veranstaltungen</string>
<string name="search">Suche</string>

Then you can use it in the app like this anywhere you need to use the string. This is an example of putting the options menu in the toolbar in Giggity app.

@Override
public boolean onCreateOptionsMenu(Menu menu) {
   super.onCreateOptionsMenu(menu);

   menu.add(Menu.NONE, 1, 5, R.string.settings)
           .setShortcut('0', 's')
           .setIcon(R.drawable.ic_settings_white_24dp)
           .setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
   menu.add(Menu.NONE, 2, 7, R.string.add_dialog)
           .setShortcut('0', 'a')
           .setIcon(R.drawable.ic_add_white_24dp)
           .setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);

   return true;
}

References:

Marker Click Management in Android Google Map API Version 2

We could display a marker on Google map to point to a particular location. Although it is a simple task sometimes we need to customise it a bit more. Recently I customised marker displayed in Connfa app displaying the location of the sessions on the map loaded from Open Event format. In this blog manipulation related to map marker is explored.

Markers indicate single locations on the map. You can customize your markers by changing the default colour, or replace the marker icon with a custom image. Info windows can provide additional context to a marker. You can place a marker on the map by using following code.

MarkerOptions marker = new MarkerOptions().position(new LatLng(latitude, longitude)).title("Dalton Hall");
googleMap.addMarker(marker);

But as you can see this may not be enough, we need to do operations on clicking the marker too, so we define them in the Marker Click Listener. We declare marker null initially so we check if the marker colour is changed previously or not.

private Marker previousMarker = null;

We check if the marker is initialized to change its colour again to initial colour, we can do other related manipulation like changing the map title here,

Note: the first thing that happens when a marker is clicked or tapped is that any currently showing info window is closed, and the GoogleMap.OnInfoWindowCloseListener is triggered. Then the OnMarkerClickListener is triggered. Therefore, calling isInfoWindowShown() on any marker from the OnMarkerClickListener will return false.

mGoogleMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
   @Override
   public boolean onMarkerClick(Marker marker) {
       String locAddress = marker.getTitle();
       fillTextViews(locAddress);
       if (previousMarker != null) {
           previousMarker.setIcon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
       }
       marker.setIcon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_BLUE));
       previousMarker = marker;

       return true;
   }
});

It’s possible to customize the colour of the default marker image by passing a BitmapDescriptor object to the icon() method. You can use a set of predefined colours in the BitmapDescriptorFactory object, or set a custom marker colour with the BitmapDescriptorFactory.defaultMarker(float hue) method. The hue is a value between 0 and 360, representing points on a colour wheel. We use red colour when the marker is not clicked and blue when it is clicked so a user knows which one is clicked.

To conclude you can use an OnMarkerClickListener to listen for click events on the marker. To set this listener on the map, call GoogleMap.setOnMarkerClickListener(OnMarkerClickListener). When a user clicks on a marker, onMarkerClick(Marker) will be called and the marker will be passed through as an argument. This method returns a boolean that indicates whether you have consumed the event (i.e., you want to suppress the default behaviour). If it returns false, then the default behaviour will occur in addition to your custom behaviour. The default behaviour for a marker click event is to show its info window (if available) and move the camera such that the marker is centered on the map.

The final result looks like this, so you the user can see which marker is clicked as its colour is changed,

   

 

References:

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

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";

    @Override
    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>() {
       @Override
       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;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    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;
    }

    @Override
    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