Simple ListView Android Developer Tutorial Part 16

From exploring the various concepts related to fundamentals and to locations and maps, I would like to look at a few UI elements.


One of the simple views is a List View. In this post, I will explore a very simple list view using all the defaults provided by Android SDK and introduce you to a customized list view in the next blog article.

A List View, by name means being able to display a list of items in an order one below the other. For creating such a view, the first thing we have to do is extend the ‘ListActivity’ (android.app.ListActivity) instead of the normal Activity class.

So, here is how the class declaration should look:

public class MyListView extends ListActivity {

The ListActivity class provides a way of binding a source of data (an array or a cursor) to a ListView object through a ListAdapter.

In android, we all know that views are defined declaratively in XML files. It is the same here too. So, if we were to create our own custom ListView, we would have a declaration of this type:

<ListView android_id="@id/android:list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#000fff"
android:layout_weight="2"
android:drawSelectorOnTop="false">
</ListView>

However, if no ListView is declared, the ListActivity picks up a default ListView which fills the screen. So, in our example we will not declare any list view.

There is one more thing we need to define and that is how each row in the list should show up. This again, there are some defaults available which have names such as simple_list_item_1, simple_list_item_2, and two_line_list_item. So, in our example, I do not declare the layout for the rows but I will be using one of the defaults provided. So, in effect, I have not declared any layout – I am using the default screen layout and row layout.

Now, that we have the layouts out of our way, what else do we need for a List View. Of course, the list of data that needs to be displayed. Just to keep it simple, I will use an array of data for the same. So, here it is:

static final String[] PENS = new String[]{
"MONT Blanc",
"Gucci",
"Parker",
"Sailor",
"Porsche Design",
"Rotring",
"Sheaffer",
"Waterman"
};

Now, how do I bind this data to the default views described earlier? This is aided by a ListAdapter interface hosted by the ListActivity class that we have extended.

We need to use the setListAdapter(..) method of the ListActivity class to bid the two (data and view). Android provides many implementations of the ListAdapter. We will use the simple ArrayAdapter.

What does the ArrayAdapter expect?

It expects the context object, the row layout and the data in an array.

So here it is:

setListAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, PENS));

With this we are done in creating the ListView.

I have added a small piece of code to show we can handle events on selecting an item in the list, by overriding the protected method shown below:

protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
Object o = this.getListAdapter().getItem(position);
String pen = o.toString();
Toast.makeText(this, "You have chosen the pen: " + " " + pen, Toast.LENGTH_LONG).show();
}

This toasts a message with the item selected.

The complete code is downloadable here.

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SQLite DB Example Android Developer Tutorial Part 12

There are 4 ways of storing data on the android platform:

• 1.    Preferences
• 2.    SQLite Database
• 3.    Files
• 4.    Network

A word about each of them here and then I will move on to an example that shows how to work with SQLite DB that comes along with the android platform.

Preferences–

Basically used for storing user preferences for a single application or across applications for a mobile. This is typically name-value pairs accessible to the context.

Databases –

Android supports creating of databases based on SQLite db. Each database is private to the applications that creates it

Files –

Files can be directly stored on the mobile or on to an extended storage medium. By default other applications cannot access it.

Network –

Data can be stored and retrieved from the network too depending on the availability.

If an application wants to store and retrieve data for its own use, without having to share the data across applications, it can access the SQLite DB directly. There is no need of a content provider. We have seen in an earlier post how to use content providers.

In this example, we will do the following:

1.    Create a database (typically a one time activity)

2.    Create a table (typically a one time activity)

3.    Insert values into the table

4.    Retrieve the values from the table

5.    Display the retrieved values as a List view

6.    Delete all the records from the table before closing the connection to the database

Step 1: Create a database:

   sampleDB =  this.openOrCreateDatabase(SAMPLE_DB_NAME, MODE_PRIVATE, null);

This opens a database defined in the constant SAMPLE_DB_NAME, if it already exists. Else it creates a database and opens it. The second parameter is operating mode : MODE_PRIVATE meaning it is accessible to only this context. The other modes are and MODE_WORLD_WRITABLE. MODE_WORLD_READABLE

Step 2: Create a Table:

sampleDB.execSQL("CREATE TABLE IF NOT EXISTS " +

                        SAMPLE_TABLE_NAME +

                        " (LastName VARCHAR, FirstName VARCHAR," +

                        " Country VARCHAR, Age INT(3));");

Step 3: Insert values into the table:

sampleDB.execSQL("INSERT INTO " +

                        SAMPLE_TABLE_NAME +

                        " Values (Makam,Sai Geetha,India,25);");

Step 4: Retrieve values

Cursor c = sampleDB.rawQuery("SELECT FirstName, Age FROM " +

                        SAMPLE_TABLE_NAME +

                        " where Age > 10 LIMIT 5", null);

           

      if (c != null ) {

            if  (c.moveToFirst()) {

                  do {

String firstName = c.getString(c.getColumnIndex("FirstName"));

                  int age = c.getInt(c.getColumnIndex("Age"));

                  results.add("" + firstName + ",Age: " + age);

                  }while (c.moveToNext());

            }

       }

Step 5: Display the values as a list

           

       this.setListAdapter(newArrayAdapter<String>(this, android.R.layout.simple_list_item_1,results));

The statement displays it as a list as the class extends a ListActivity.

Step 6: Delete the values from the table in the finally part of the try block

finally {

            if (sampleDB != null)

                  sampleDB.execSQL("DELETE FROM " + SAMPLE_TABLE_NAME);

                  sampleDB.close();

        }

It is as simple as this to work with the SQLite DB even in android. No different from a desktop application. However, there are various overloaded methods of query() provided by the SQLIteDatabase class which can be more optimally used instead of execSQL.

The complete code for this example is downloadable here.

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Kamus Cambridge Dictionary of American English 2nd Edition Full v2 12 Instal Offline

Persyaratan minimum: semua Android

Kamus Cambridge Dictionary of American English menyediakan lebih dari 40.000 definisi kata dan lebih 200 juta perkataan American English. Isi termasuk tiap-tiap kata dan ungkapan yang biasa digunakan di Amerika.

Format Kamus - MSDict:
Kamus Cambridge Dictionary of American English ini didesign dengan format elektronik yang telah berpengalaman menyediakan bahan elektronik untuk handphone.

Download link: Part 1 | Part 2 (password untuk ekstrak: unlockme)

Prosedur instalasi:

• Download kedua file dari link di atas (part 1 & part 2)
• Ekstrak dalam satu folder, nama folder setelah ekstrak adalah Cambridge Dictionary of American English
• Di dalam folder tadi akan ada 3 folder lagi (Application, Databases dan Keygen*) dan 1 file txt berisi instruksi instalasi
  
• Buat satu folder di sdcard handphone dengan nama Mobile Systems
• Kopi folder berikut: com.mobisystems.msdict.embedded.wireless.cambridge.american (di dalam folder Databases) ke dalam sdcardMobile Systems di handphone
• Instal file com.mobisystems.msdict.embedded.wireless.cambridge.american_17.apk di dalam folder Application.
• Pertama kali dijalankan akan ada pertanyaan where to download files, pilih sdcard
• Kemudian akan ada pertanyaan lagi untuk unlock, tekan unlock
• Jalankan Keygen.exe yang ada di dalam folder Keygen
• Pilih MSDict Cambridge Dictionary of American English v4.10 di Keygen
• Masukkan no IMEI handhpone kamu
• Tekan Generate dan masukkan kode tersebut di aplikasi di handphone.

Catatan (penting sebelum ekstrak):

• IMEI handphone bisa dilihat di Setting->About Phone->Status atau tekan *#06#
• Sebagian antivirus mendetek file Keygen.exe sebagai virus dan kemungkinan akan otomatis didelete. Jangan khawatir karena file ini bukan virus.
• Disarankan untuk menon-aktifkan antivirus sebelum ekstrak atau memasukkan folder di atas sebagai kategori aman (tidak discan oleh antivirus)
  

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Android Developers Backstage Episode 12 The Jake Show

In a startling and electrifying break with ancient tradition (born of laziness rather than policy), Tor and Chet are joined in this podcast by external developer (i.e., non-Googler) Jake Wharton. Jake has worked on and with many important Android open source libraries. We talk with Jake about these projects and various other aspects of Android development in general.

Subscribe to the podcast feed or download the audio file directly.

Relevant Links:

Retrofit: http://square.github.io/retrofit/

Picasso: http://square.github.io/picasso/

Dagger: http://square.github.io/dagger/

OkHttp: http://square.github.io/okhttp/

Butter Knife: http://jakewharton.github.io/butterknife

Robolectric: http://robolectric.org/

Espresso: https://code.google.com/p/android-test-kit/

AssertJ Android: http://square.github.io/assertj-android

Jake: google.com/+JakeWharton

Tor: google.com/+TorNorbye

Chet: google.com/+ChetHaase

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Android UI – Inflate from XML Dynamic UI Creation

We have seen that we can declare User Interface in Android through XML or we can even create the UI Programmatically. Now, we will see how we can mix the two and use it for building dynamic User Interfaces. One example of such a case would be when on a particular action of the user on one of the UI elements, you need more UI elements to appear on the same screen. How do we achieve this?

You can do it in two ways:

1.       The dynamic part of the UI can be created programmatically. However we saw in my earlier tutorial that it is not a very good way to mix UI and code.  So, we can

2.       Define the dynamic UI too as an XML and use XML inflation to include it into the existing UI.

We will see how to do the 2^ndway, which probably is a good practice too.

As always, again a very simple example. Assume I have a very simple linear layout. In that I want to include a button. I can do it as part of the mail XML itself. However, assume that this button is supposed to be reused in many activities and hence I have defined it as a separate XML. How do I include it into the main XML?

So, here is the main.xml

<?xml version="1.0"encoding="utf-8"?>

<LinearLayout >="http://schemas.android.com/apk/res/android"

    android:orientation="vertical"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:id="@+id/layout1"

    >

</LinearLayout>

Here is the buttons.xml that is also created in the res/layout folder:

<?xml version="1.0"encoding="utf-8"?>

<Button >="http://schemas.android.com/apk/res/android"

        android:id="@+id/button_small_left"

 style="?android:attr/buttonStyleSmall"

        android:text="Press to close"

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"/>

And here is the Activity’s onCreate(…) method of the InflateView class:

    public voidonCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        final LayoutInflater  inflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        Button b = (Button)inflater.inflate(R.layout.buttons,

                null);

       

        lLayout = (LinearLayout)findViewById(R.id.layout1);

        lLayout.addView(b);

First 3 lines must be familiar. In the 4^thline, I am getting a handle to the LayoutInflater through the getSystemService(…) method.  This inflater has a method inflate to which I pass the buttons.xml by passing the parameter R.layout.buttons. Then, I try to append this button to the Linear Layout that already exists and is set as the view in line 2 setContentView(R.layout.main). How to append? I get a handle to the LinearLayoutlLayout and add the new button to it in the last line!

That simple to inflate an XML and append it to an existing view!

However, I have gone ahead and added another bit to this program as shown below:

        b.setOnClickListener(new OnClickListener() {

           

            public void onClick(View v) {

                  //restrict to adding only 1 textview child element

                  if (lLayout.getChildAt(2) == null)

                  {

                  TextView tv = (TextView)inflater.inflate(R.layout.text, null);

                  lLayout.addView(tv);

                  }

            }

        });

On the click of this dynamically added button, I am showing how we can add more to the UI dynamically through inflation. Assume, on the click of the button, you want to show some new text. This TextView is defined in another XML called text.xml which is also in the res/layout folder.

So, I am inflating from this XML and appending it to the LinearLayout view. So, a lot can be achieved for dynamic UI through inflation.

You can download the complete sample code here.

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