Understanding Android Manifest File

                                           

                                               Android Manifest file

Every Android application must have a manifest file. Manifest file contains very essential information about the application. Having a proper understanding of manifest is necessary for Android application development.

A manifest file contains following information of Android application

• Package name: The package name serves as a unique identifier for the application.
• Activities : All activities are declared in manifest file.
• Services : All the services used in you application must be declared in activities.
• BroadcastReceivers : If your application has broadcast receiver, it must be declared in the manifest file.
• Permissions : Lists the permissions required for your application.
• API Level : It declares the minimum, maximum and target API level of the Android API that the application requires.
• Application version : specifies the application version.
• Features used in application : it specifies which android feature the application require to run properly.
• Supported screen size : Android devices comes in many shapes and size. You need to specify which screen types your application supports.

Let us have a sample manifest file and discuss each element in detail.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.android.calculator"

    android:versionCode="1"

    android:versionName="1.1" >

    <uses-sdk

        android:minSdkVersion="8"

        android:maxSdkVersion="16"

        android:targetSdkVersion="15" />

   

    <!--  list of permissions  -->

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

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

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

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

   

    <!--  Screen types supported  -->

    <supports-screens

        android:smallScreens="true"

        android:normalScreens="true"

        android:largeScreens="false"/>

   

    <!--  Features needed -->

    <uses-feature android:name="android.hardware.bluetooth" />

    <uses-feature android:name="android.hardware.camera" />

    <application

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name=".MainActivity"

            android:label="@string/title_activity_main" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

       

         <receiver android:name=".SmsReceiver">

            <intent-filter>

                <action android:name="android.provider.Telephony.SMS_RECEIVED" />

            </intent-filter>

        </receiver>

        <service  android:name="VibrateService"/>

       

    </application>

</manifest>

Let us discuss each attribute

1:   package="com.android.calculator"

package name of the application is "com.android.calculator".

2: android:versionName="1.1"

version of application is 1.1

3: <uses-sdk

        android:minSdkVersion="8"

        android:maxSdkVersion="16"

        android:targetSdkVersion="15" />

minSdkVersion attribute: specifies the lowest API level that the application supports, here it is 8.

maxSdkVersion attribute: specifies the maximum/highst API level that the application supports, here it is 16.

targetSdkVersion attribute: specifies the optimun API level that the application supports, here it is 15.

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

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

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

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

The application has requested four permissons

Permission to read contacts.

Permission to access internet.

Permission to vibrate the device.

Permission to receive the SMS.

Note: If you not declare the required permission in the manifest and use the feature in your application you will get “SecurityException”. List of all imporatnt permissions is given in the appendix.

5:    <supports-screens

        android:smallScreens="true"

        android:normalScreens="true"

        android:largeScreens="false"/>

application supports devices with small and normal screens but not support devices with large screens.

6: <uses-feature android:name="android.hardware.bluetooth" />

   <uses-feature android:name="android.hardware.camera" />

Application uses camera and Bluetooth hardware of the device.

7: the     <application> tag

In the application tag all activities, services and broadcast receivers are declared.

Romantic Messages for Lovers

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Romantic Messages for Lovers

Meeting you was the best day of my life.

When you are next to me, or when we are apart, You are always the first in my thoughts and in my heart.

I never ever thought I’d like you this much and I never planned to have you on my mind this often.

I love the way you love me.

Spring drops and the sun outside the window tell me that this spring will be the flowering of our love.

I can’t spend a day without you, can’t you see? I love you so much. You are a part of me and this is forever.

You make me happy in a thousand ways. I love you to the moon and back, and I have no idea what I would do, if I lost you, because I feel like I will lose my entire world.

Nothing is going change my love for you, you are the man, who helped me to find myself in this life.

I want to be your favorite hello and your hardest goodbye.

Your smile takes my breath away. It took my breath away on the day we met, on our wedding day, today, and every day in between.

Thank you for teaching me what marrying your best friend means.

I wish every day you could see yourself the way I see you. Because I see you as absolutely perfect.

When I put my arms around you, I never want to let you go.

My life was black and white until you came in and added color.

Android Spinner Tutotial

Spinner is a widget which provides a quick way to select a value from a set. A spinner presents multiple options/items to the user from which user can select one option.

For ex.  In game application when we want user to select a particular level he/she wants to play, we can use spinner to multiples levels in which can select one level.

Using Spinner

Steps to use spinner in your application

1: Defining the spinner in your .xml/layout file by using “Spinner” tag

<!—Declaring Spinner in xml -->

    <Spinner

        android:id="@+id/spinner"

        android:layout_marginTop="20dp"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:prompt="@string/spinner_title"

    />

2: Create an array/arraylist of strings that will be set as the items of spinner.

String spinnerItems[]={"Level 1","Level 2","Level 3","Level 4","Level 5",};

3: Create adapter and set it with spinner

// Create adapter for spinner

ArrayAdapter  dataAdapter = new ArrayAdapter(this, android.R.layout.simple_spinner_item, spinnerItems);

// attaching data adapter to spinner

mySpinnerObject.setAdapter(dataAdapter);

4: Set  clicklistener on Spinner

// set clicklistener on Spinner

 mySpinnerObject.setOnItemSelectedListener(this);

5: override  onItemSelected() method, this method gets called by the System when an item is selected. This method receives the position parameter which signifies the index of the array/arraylist which is selected by the user.

@Override

 public void onItemSelected(AdapterView<?> parent, View view, int position, long id)

{

                         

// get the selected Spinner's Item

            String itemSelected = parent.getItemAtPosition(position).toString();

}

Let put all this together and develop an android application to learn how to use spinner.

Demo Application: “Working with Spinner”

What we will do: We will present a list of levels “Level 1,Level 2,Level 3,Level 4,Level 5" to the user and show the level selected by the user using Toast.

activity_main.xml

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

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

    android:orientation="vertical"

    android:padding="10dip"

    android:layout_width="fill_parent"

    android:layout_height="wrap_content">

    <TextView

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:text="Select the Level"

        android:layout_marginTop="20dp"

        android:textColor="#0000FF"

        android:textSize="20dp"

        android:textStyle="bold"

    />

    <!-- Spinner Element -->

    <Spinner

        android:id="@+id/spinner"

        android:layout_marginTop="20dp"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

    />

  </LinearLayout>

SpinnerMainActivity.java

public class SpinnerMainActivity extends Activity implements OnItemSelectedListener

{

     Spinner mySpinner;

      /* create array of string of levels

     * to be set as Spinner Item

     */

    String spinnerItems[]={"Level 1","Level 2","Level 3","Level 4","Level 5",};

   

     @Override

     protected void onCreate(Bundle savedInstanceState)

     {

          super.onCreate(savedInstanceState);

          setContentView(R.layout.activity_main);

         

          // get the Spinner reference

               mySpinner = (Spinner) findViewById(R.id.spinner);

       

               // set clicklistener on Spinner

               mySpinner.setOnItemSelectedListener(this);

       

              // Create adapter for spinner

          ArrayAdapter  dataAdapter = new ArrayAdapter(this, android.R.layout.simple_spinner_item, spinnerItems);

          // Drop down layout style - list view with radio button

                    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

          // attaching data adapter to spinner

          mySpinner.setAdapter(dataAdapter);

     }

     /* onItemSelected() method gets called by the System

      * when an item is selected

      * This method receives the position parameter

      * which signifies the index of the array

      * which is selected

      */

     @Override

        public void onItemSelected(AdapterView<?> parent, View view, int position, long id)

        {

           

              // get the selected Spinner's Item

              String itemSelected = parent.getItemAtPosition(position).toString();

              // Showing selected spinner item

              Toast.makeText(getApplicationContext(),  itemSelected+"  Selected", Toast.LENGTH_LONG).show();

          }

      

      

       @Override

          public void onNothingSelected(AdapterView view)

          {

              // TODO Auto-generated method stub

          }

}