How to create AnalogClock and DigitalClock in Android.

Analogclock and Digitalclock views 

* The AnalogClock view displays an analog clock with two hands — one for minutes and one for hours.

* Its counterpart, the DigitalClock view, displays the time digitally. Both display the system time, and do not allow you to display a particular time.

* Hence, if you want to display the time for a particular region, you have to build your own custom views.

Using the AnalogClock and DigitalClock views are straightforward; simply declare them in your XML file (such as main.xml), like this:

<?xml ​version=”1.0”​encoding=”utf-8”?>
<LinearLayout ​xmlns:android=”http://schemas.android.com/apk/res/android” ​​​​android:orientation=”vertical”
​​​​android:layout_width=”fill_parent”
​​​​android:layout_height=”fill_parent” ​​​​>

<AnalogClock ​​
​​android:layout_width=”wrap_content” ​​
​​android:layout_height=”wrap_content” />

<DigitalClock
​​​​android:layout_width=”wrap_content” ​​
​​android:layout_height=”wrap_content” />

</LinearLayout>

Android ProgressBar Example.

ProgressBar View 

* The ProgressBar view provides visual feedback of some ongoing tasks, such as when you are per- forming a task in the background.

* For example, you might be downloading some data from the Web and need to update the user about the status of the download.

* In this case, the ProgressBar view is a good choice for this task.


1 . Using Eclipse, create an Android project and name it as ProgressBarView. 

2 . Modify the main.xml file located in the res/layout folder by adding the following code in bold: 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
   
 <ProgressBar android:id="@+id/progressbar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        style="?android:attr/progressBarStyleHorizontal" />
       
</LinearLayout>

3 . In the MainActivity.java file, add the following statements in bold:

package com.emergingandroidtech.ProgressBarView;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.ProgressBar;

public class MainActivity extends Activity {
   
    private static int progress;
    private ProgressBar progressBar;
    private int progressStatus = 0;
    private Handler handler = new Handler();
       
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       
        progress = 0;
        progressBar = (ProgressBar) findViewById(R.id.progressbar);
        progressBar.setMax(200);
       
        //---do some work in background thread---
        new Thread(new Runnable()
        {

            public void run()
            {
                //---do some work here---
                while (progressStatus < 200)
                {
                    progressStatus = doSomeWork();
                    //---Update the progress bar---
                    handler.post(new Runnable()
                    {
                        public void run() {
                            progressBar.setProgress(progressStatus);
                        }
                    });
                }

                //---hides the progress bar---
                handler.post(new Runnable()
                {
                    public void run()
                    {
                        //---0 - VISIBLE; 4 - INVISIBLE; 8 - GONE---
                        progressBar.setVisibility(8);
                    }
                });
            }   

            //---do some long lasting work here---
            private int doSomeWork()
            {
                try {
                    //---simulate doing some work---
                    Thread.sleep(50);
                } catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
                return ++progress;
            }
        }).start(); 
    }
}

4 . It shows the ProgressBar animating. After about five seconds, it will disappear.

How to update an activity from BroadcastReceiver ?

Updating an Activity from a BroadcastReceiver

If you’ll want to send the SMS message back to the main activity of your application.

For example, you might wish to display the message in a TextView.

The following example demonstrates how you can do this.

Creating a View-Based Application Project

1- Add the following lines in bold to the main.xml file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<Button
    android:id="@+id/btnSendSMS" 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Send SMS" />   
   
<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />
   
</LinearLayout>

2 . Add the following statements in bold to the SMSReceiver.java file: 

package com.emergingandroidtech.SMS;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.SmsMessage;
import android.widget.Toast;

public class SMSReceiver extends BroadcastReceiver
{
    @Override
    public void onReceive(Context context, Intent intent)
    {       
        //---get the SMS message passed in---
        Bundle bundle = intent.getExtras();       
        SmsMessage[] msgs = null;
        String str = "";           
        if (bundle != null)
        {
            //---retrieve the SMS message received---
            Object[] pdus = (Object[]) bundle.get("pdus");
            msgs = new SmsMessage[pdus.length];           
            for (int i=0; i<msgs.length; i++){
                msgs[i] = SmsMessage.createFromPdu((byte[])pdus[i]);               
                str += "SMS from " + msgs[i].getOriginatingAddress();                    
                str += " :";
                str += msgs[i].getMessageBody().toString();
                str += "\n";       
            }
            //---display the new SMS message---
            Toast.makeText(context, str, Toast.LENGTH_SHORT).show();
    
        
            //---send a broadcast intent to update the SMS received in the activity---
            Intent broadcastIntent = new Intent();
            broadcastIntent.setAction("SMS_RECEIVED_ACTION");
            broadcastIntent.putExtra("sms", str);
            context.sendBroadcast(broadcastIntent);
        }                        
    }
}

3 . Add the following statements in bold to the MainActivity.java file: 

package com.emergingandroidtech.SMS;

import android.app.Activity;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;

import android.os.Bundle;
import android.telephony.SmsManager;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
   
    Button btnSendSMS;       
    IntentFilter intentFilter;   
   
    private BroadcastReceiver intentReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            //---display the SMS received in the TextView---
            TextView SMSes = (TextView) findViewById(R.id.textView1);
            SMSes.setText(intent.getExtras().getString("sms"));
        }
    };
       
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);       
       
        //---intent to filter for SMS messages received---
        intentFilter = new IntentFilter();
        intentFilter.addAction("SMS_RECEIVED_ACTION");

       
       
        btnSendSMS = (Button) findViewById(R.id.btnSendSMS);       
        btnSendSMS.setOnClickListener(new View.OnClickListener()
        {
            public void onClick(View v)
            {               
                //sendSMS("5554", "Hello my friends!");
               
                Intent i = new
                    Intent(android.content.Intent.ACTION_VIEW);
                i.putExtra("address", "5556; 5558; 5560");
                i.putExtra("sms_body", "Hello my friends!");
                i.setType("vnd.android-dir/mms-sms");
                startActivity(i);
                                          
            }
        });
    }
       
    @Override
    protected void onResume() {
        //---register the receiver---
        registerReceiver(intentReceiver, intentFilter);
        super.onResume();
    }
   
    @Override
    protected void onPause() {
        //---unregister the receiver---
        unregisterReceiver(intentReceiver);
        super.onPause();
    }
       
  
   
        //---sends an SMS message to another device---
    private void sendSMS(String phoneNumber, String message)
    {    
       //...
    }

}

4. Add the following lines in Android Manifest file .

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.emergingandroidtech.SMS"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".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>

        <receiver android:name=".SMSReceiver">
            <intent-filter>
                <action android:name=
                    "android.provider.Telephony.SMS_RECEIVED" />
            </intent-filter>
        </receiver>

    </application>
    <uses-sdk android:minSdkVersion="8" />

<uses-permission android:name="android.permission.SEND_SMS"></uses-permission>
<uses-permission android:name="android.permission.RECEIVE_SMS"></uses-permission>
</manifest>

5 .Using the DDMS, send an SMS message to the emulator. It shows the Toast class displaying the message received, and the TextView showing the message received.

Calling Built-In Application using Intent in android

You have seen how to call activities within your own application.
One of the key aspects of Android programming is using the intent to call activities from other applications.
In particular, your application can call the many built-in applications that are included with an Android device.
For example, if your application needs to enable a user to call a particular person saved in the Contacts application, you can simply use an Intent object to bring up the Contacts application, from which the user can select the person to call.
This enables your application to present a consistent user experience, and enables you to avoid building another application to retrieve all the contacts in the Contacts application.
The following Example demonstrates how to call some of the built-in applications commonly found on an Android device.

Calling Built-in Applications Using intents

1 . Using Eclipse, create a new Android project and name it Intents.

2 . Add the following statements in bold to the main.xml file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
<Button
    android:id="@+id/btn_webbrowser"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Web Browser" />   
<Button
    android:id="@+id/btn_makecalls"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Make Calls" />  
<Button
    android:id="@+id/btn_showMap"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Show Map" />   
<Button
    android:id="@+id/btn_chooseContact"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Choose Contact" />

 </LinearLayout>

3 . Add the following statements in bold to the MainActivity.java file: 

package com.emergingandroidtech.Intents;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {
   
    Button b1, b2, b3, b4 ;
    int request_Code = 1;
   
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       
        //---Web browser button---
        b1 = (Button) findViewById(R.id.btn_webbrowser);
        b1.setOnClickListener(new OnClickListener()
        {
            public void onClick(View arg0){
                /*
                Intent i = new
                    Intent(android.content.Intent.ACTION_VIEW,
                      Uri.parse("http://emergingandroidtech.blogspot.in/"));
                */
               
                //---OR---
                Intent i = new
                Intent("android.intent.action.VIEW");               
                //Intent(android.content.Intent.ACTION_VIEW);               
                i.setData(Uri.parse("http://emergingandroidtech.blogspot.in/"));
               
                startActivity(i);               
            }
        });
       
        //---Make calls button---
        b2 = (Button) findViewById(R.id.btn_makecalls);
        b2.setOnClickListener(new OnClickListener()
        {
            public void onClick(View arg0){
                /*
                Intent i = new
                    Intent(android.content.Intent.ACTION_DIAL);
                startActivity(i);
                */
               
                //---OR---
               
                Intent i = new
                    Intent(android.content.Intent.ACTION_CALL,
                  Uri.parse("tel:+651234567"));
                startActivity(i);
                               
            }
        });  
       
        //---Show Map button---
        b3 = (Button) findViewById(R.id.btn_showMap);
        b3.setOnClickListener(new OnClickListener()
        {
            public void onClick(View arg0){
                Intent i = new
                    Intent(android.content.Intent.ACTION_VIEW,
                  Uri.parse("geo:37.827500,-122.481670"));               
                startActivity(i);               
            }
        });  
       
        //---Choose Contact button---
        b4 = (Button) findViewById(R.id.btn_chooseContact);
        b4.setOnClickListener(new OnClickListener()
        {
            public void onClick(View arg0){
                Intent i = new
                Intent(android.content.Intent.ACTION_PICK);                                       
                //i.setType(ContactsContract.Contacts.CONTENT_TYPE);
                i.setType(ContactsContract.CommonDataKinds.Phone.CONTENT_TYPE);
                startActivityForResult(i,request_Code);               
            }
        });               

            
    }
   
    public void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        if (requestCode == request_Code)
        {
             if (resultCode == RESULT_OK)
               {               
                   Toast.makeText(this,data.getData().toString(),
                       Toast.LENGTH_SHORT).show();
                   Intent i = new Intent(
                           android.content.Intent.ACTION_VIEW,
                           Uri.parse(data.getData().toString()));
                   startActivity(i);
               }           
        }
    }
}

4 .Click the Web Browser button to load the Browser application on the emulator.
 
5 . Click the Make Calls button and the Phone application will load .

6 . Similarly, to load the Maps application, click the Show Map button.
 
NOTE  In order to display the Maps application, you need to run the application on an AVD that supports the Google APIs.
 
7 . Click the Choose Contact application to show a list of contacts that you can select . Selecting a contact will show details about that contact.

How to use ScrollView in Android ?

Scrollview 

* A ScrollView is a special type of FrameLayout in that it enables users to scroll through a list of views that occupy more space than the physical display.

* The ScrollView can contain only one child view or ViewGroup, which normally is a LinearLayout.

* NOTE 
-> Do not use a ListView together with the ScrollView.

-> The ListView is designed for showing a list of related information and is optimized for dealing with large lists.

The following main.xml content shows a ScrollView containing a LinearLayout, which in turn contains some Button and EditText views:

<?xml​ version=”1.0”​encoding=”utf-8”?>

<ScrollView ​​​​
android:layout_width=”fill_parent”
​android:layout_height=”fill_parent” ​
​​​xmlns:android=”http://schemas.android.com/apk/res/android” ​​​​>

​​​​<LinearLayout
​​​​​​​​android:layout_width=”fill_parent”
​​​​​​​​android:layout_height=”wrap_content” ​​
​​​​​​android:orientation=”vertical” ​​​​​​​​>

​​​​​​​​<Button
​​​​​​​​​​​​android:id=”@+id/button1” ​
​​​​​​​​​​​android:layout_width=”fill_parent” ​​
​​​​​​​​​​android:layout_height=”wrap_content” ​
​​​​​​​​​​​android:text=”Button​1” ​​​​​​​​​​​​/>

​​​​​​​​<Button ​​​​​​​​​​​​
android:id=”@+id/button2” ​​
​​​​​​​​​​android:layout_width=”fill_parent” ​​
​​​​​​​​​​android:layout_height=”wrap_content” ​​
​​​​​​​​​​android:text=”Button​2” ​​​​​​​​​​​​/> ​​​​​​​​<Button ​​​​​​​​​​​​android:id=”@+id/button3” ​​​​​​​​​​​​android:layout_width=”fill_parent” ​​​​​​​​​​​​android:layout_height=”wrap_content” ​​​​​​​​​​​​android:text=”Button​3” ​​​​​​​​​​​​/> ​​​​​​​​<EditText ​​​​​​​​​​​​android:id=”@+id/txt” ​​​​​​​​​​​​android:layout_width=”fill_parent” ​​​​​​​​​​​​android:layout_height=”300px” ​​​​​​​​​​​​/> ​​​​​​​​<Button ​​​​​​​​​​​​android:id=”@+id/button4” ​​​​​​​​​​​​android:layout_width=”fill_parent” ​​​​​​​​​​​​android:layout_height=”wrap_content” ​​​​​​​​​​​​android:text=”Button​4” ​​​​​​​​​​​​/> ​​​​​​​​<Button ​​​​​​​​​​​​android:id=”@+id/button5” ​​​​​​​​​​​​android:layout_width=”fill_parent” ​​​​​​​​​​​​android:layout_height=”wrap_content” ​​​​​​​​​​​​android:text=”Button​5” ​​​​​​​​​​​​/> ​​​​</LinearLayout> </ScrollView>
Figure 3-12 shows the ScrollView enabling the users to drag the screen upward to reveal the views located at the bottom of the screen.

Dynamically update option menu items in Android.

Updating Menu Items Dynamically

By overriding your Activity’s onPrepareOptionsMenu method, you can modify a Menu based on an application’s current state immediately before the Menu is displayed.

This lets you dynamically disable/enable Menu Items, set visibility, and modify text.

Note that the onPrepareOptionsMenu method is triggered whenever the menu button is clicked, the overflow menu displayed, or the Action Bar is created.


To modify Menu Items dynamically, you can either record a reference to them from within the onCreateOptionsMenu method when they’re created, or you can use the findItem method on the Menu object, where onPrepareOptionsMenu is overridden.

Modifying Menu Items dynamically

@Override 

public boolean onPrepareOptionsMenu(Menu menu) 

{  

     super.onPrepareOptionsMenu(menu);
  

           MenuItem menuItem = menu.findItem(MENU_ITEM);
           [ ... modify Menu Items ... ]
 

    return true; 

}

Bluetooth Communication Android.

Bluetooth Communications

The Android Bluetooth communications APIs are wrappers around RFCOMM, the Bluetooth radio frequency communications protocol. RFCOMM supports RS232 serial communication over the Logical Link Control and Adaptation Protocol (L2CAP) layer.
 

In practice, this alphabet soup provides a mechanism for opening communication sockets between two paired Bluetooth devices.
 

Before your application can communicate between devices, the devices must be paired (bonded). If users attempt to connect two unpaired devices, they will be prompted to pair them before the connection is established.
 

You can establish an RFCOMM communication channel for bidirectional communications using the following classes. 

BluetoothServerSocket — Used to establish a listening socket for initiating a link between devices. To establish a handshake, one device acts as a server to listen for, and accept, incoming connection requests. 

BluetoothSocket — Used to create a new client to connect to a listening Bluetooth Server Socket. Also returned by the Bluetooth Server Socket after a connection is established. 

Once a connection is established, Bluetooth Sockets are used by both the server and client to transfer data streams.
 

When creating an application that uses Bluetooth as a peer-to-peer transport layer, you’ll need to implement both a Bluetooth Server Socket to listen for connections and a Bluetooth Socket to initiate a new channel and handle communications.

When connected, the Bluetooth Server Socket returns a Bluetooth Socket that’s then used by the server device to send and receive data. This server-side Bluetooth Socket is used in exactly the same way as the client socket. The designations of server and client are relevant only to how the connec- tion is established; they don’t affect how data fl ows after that connection is made.