Difference between StartActivityForResult, startActivity

Many of them  have confution about startActivity and startActivityForResult() methods.
startActivity() is to start another activity
StartActivityForResult() is to receive a result. The activity has to return a result.
When it returns a result, it sends as another intent object and activity recives result in onActivityResult() and here we can handle.
We need to pass an integer arg to startActivityForResult() method. So that request code will identifies the request.
When you get the result intent, callback provides the same request code to identify the result.

see this example:
  Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        startActivityForResult(intent, 1);
@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == 1){           
        }       

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Tabs like with ActionBar

 TabActivity is depreciated  in Api 13. Tabs are presented in latest versions with ActionBar.
ActionBar.newTab().

So, prefer to not to use depreciated classes and methods. So use latest classes and methods.

Here is the simple example of creating Tab like activity using fragments.



 MobEngineersActivity.java

package com.srinivas.mobengineers;

import android.app.ActionBar;
import android.app.Activity;
import android.app.ActionBar.Tab;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Context;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.os.Bundle;
import android.widget.Toast;


public class MobEngineersActivity extends Activity {
    public static Context appContext;
   
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        appContext = getApplicationContext();

 
        ActionBar actionbar = getActionBar();       // initilize actionBar
        actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);     // set navigation mode
       
        ActionBar.Tab Category1Tab = actionbar.newTab().setText("FOOD");
        ActionBar.Tab Category2Tab = actionbar.newTab().setText("BEVERAGES");
       
        Fragment FoodFragment = new FoodFragment();
        Fragment BeveragesFragment = new BeveragesFragment();
       CategoryTab.setTabListener(new MyTabsListener(FoodFragment));
      BeveragesTab.setTabListener(new MyTabsListener(BeveragesFragment));

        actionbar.addTab(FoodTab);
        actionbar.addTab(BeveragesTab);
    }
Food.java

public class FoodFragment extends Fragment {
   
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    return inflater.inflate(R.layout.afragment, container, false);
    }
  }

Beverages.java
public class FoodFragment extends Fragment {
   
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    return inflater.inflate(R.layout.afragment, container, false);
    }
  }

 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:id="@+id/ll"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center">
    <LinearLayout
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

 </LinearLayout>
</LinearLayout>

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Bluetooth -Android Programming

  Android supports Bluetooth for wireless connectivity. It comes with API of android bluetooth.


We have different classes in the API

BluetoothAdapter: It represents local Bluetooth Adapter.Using this class, we can discover the devices near by.Uisng this we can create BluetoothServerSocket for listening from other devices.

 BluetoothDevice: By using this we can request connection to remote device through BluetoothSocket.

BluetoothSocket: We can exchange the data with other Bluetooth Device.

BluetoothServerSocket: it listens the incoming request. To connect any device, one device  must open a server socket.


BluetoothProfile:It is an interface for wireless devices.

Bluetooth: Using this class, we can connect to Bluetooth Headset.

BluetoothHealth: It represents a health device profile that controls Bluetooth service.
BluetoothA2dp(Advanced Audio Distribution Profile): It tells how audio quality streamed from one mobile to other .

BluetoothProfile.ServiceListener: It gives notification when the client connects or disconnects.


To use Bluetooth in Android, we need to declare permissions in manifest.xml

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


How to check whether the device support Bluetooth or not?

BluetoothAdapter btAdapter=BluetoothAdapter.getDefaultAdapter();
if( btAdapter==null){
//device doesnot support Bluetooth.
 }
else{ //device support bluetooth.


How to enable Bluetooth:

 //Prompt user to turn on Bluetooth

Intent enableI = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableI, REQUEST_ENABLE_BT);

        // Set up a pointer to  remote node using address.
        BluetoothDevice device = btAdapter.getRemoteDevice(address);  


/ Establish connection. 
  bltSocket.connect();

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What is Bluetooth?

-->

        Bluetooth is a wireless technology for connecting shortest distance clients(creates personnel area network) within the range of 10 meters with the frequency of 2.4 GHZ of unlicensed band. To connect to the other client, the client also have Bluetooth. It is the greatest technology for replacing the cables for short distances.
     If we compare to the other systems, Bluetooth file transfer is faster packet transfer. It uses fastest acknowledgement, frequency hopping and unlicensed ISM band.

  At Present, most of the electronic goods coming with Bluetooth technology like Tv, mouse, audio devices, mobiles, remotes, computers etc.

cost of the Bluetooth device is cheaper than any other wireless technology.


How to use the Bluetooth and how to connect to other Bluetooth device programatically we can see in later topics.


  
 

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Fragments- ActionBar android

public class StartActivity extends Activity {
    public static Context appContext;
   
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        appContext = getApplicationContext();

          ActionBar actionbar = getActionBar();
        actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
       
        ActionBar.Tab PlayerTab = actionbar.newTab().setText("SONGS");
        ActionBar.Tab StationsTab = actionbar.newTab().setText("VIDEOS");

       ActionBar.Tab PhotosTab = actionbar.newTab().setText("PHOTOS");       
        Fragment sFragment = new SongsFragment();
        Fragment vFragment = new VideosFragment();

        sTab.setTabListener(new MyTabsListener(sFragment));
        vTab.setTabListener(new MyTabsListener(vFragment));

        actionbar.addTab(sTab);
        actionbar.addTab(vTab);
}



 
SongsFragment.java

public class SongsFragment extends Fragment {
   
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.songsfragment, container, false);
    }
   
}






public class VideosFragment extends Fragment {
   
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.videosfragment, container, false);
    }




PhotosFragment.java



 
public class PhotosFragment extends Fragment {
   
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.photosfragment, container, false);
    }
   
}


xml


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
   android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent" android:layout_gravity="center">
    <LinearLayout
        android:id="@+id/fragment_tab"
        android:layout_gravity="bottom"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

 </LinearLayout>
</LinearLayout>
 

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Creating Bitmap

To Create Bitmap 

Bitmap bmp = Bitmap.createBitmap((int)
getWindowManager().getDefaultDisplay().getWidth(), (int)
getWindowManager().getDefaultDisplay().getHeight(), Bitmap.Config.ARGB_8888);

To create Bitmap from resources

Bitmap image=BitmapFactory.decodeResource(context.getResources(),R.drawable.ic_launcher); 

Bitmap Configurations:

ALPHA_8  : 8 bits on Alpha channel, and no other colours.

ARGB_4444: 4 bits per color channel includes alpha,

ARGB_8888: 8 bits per color channel includes alpha,

RGB_565  : 5 bits for Red,6 bits for Green,5 bits for Blue 

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TabHost- Tabs Android

 TabActivity:


In android, Using tabs, we can open multiple activities within single screen.
Three ways to create Tabs.

1. extends class from TabActivity or ActivityGroup

2. extending Activity and  use LocalActivityManager

3. using fragments ( Api 11 required).

Here is the sample working code for Tabs



package com.srinivas.tabs;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.app.Activity;
import android.app.LocalActivityManager;
import android.app.TabActivity;
import android.content.Intent;
import android.content.res.Resources;
import android.widget.TabHost;

public class MainActivity extends Activity {
    private static TabHost tabHost;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.tabs);
        tabHost = (TabHost) findViewById(R.id.tabhost);
        LocalActivityManager mLocalActivityManager = new LocalActivityManager(this, false);
        mLocalActivityManager.dispatchCreate(savedInstanceState);
        tabHost.setup(mLocalActivityManager);
        Resources res = getResources();
       
        TabHost.TabSpec spec;

        Intent songintent = new Intent().setClass(this, SongsActivity.class);

        spec = tabHost.newTabSpec("songs")
                .setIndicator("Songs", res.getDrawable(R.drawable.ic_launcher))
                .setContent(logintent);
        tabHost.addTab(spec);

        Intent videointent = new Intent().setClass(this, VideosActivity.class);
        spec = tabHost
                .newTabSpec("video")
                .setIndicator("Videos", res.getDrawable(R.drawable.ic_launcher))
                .setContent(viodeintent);
        tabHost.addTab(spec);

        Intent booksintent = new Intent().setClass(this, BooksActivity.class);
        spec = tabHost.newTabSpec("books")
                .setIndicator("Books", res.getDrawable(R.drawable.ic_launcher))
                .setContent(booksintent);
        tabHost.addTab(spec);

       tabHost.setCurrentTab(0);
}
}


tabs.xml

<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:id="@+id/tabhost"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <RelativeLayout
        android:orientation="vertical"

        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:padding="5dp"
        />
        <TabWidget
            android:id="@android:id/tabs"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="bottom"
            android:layout_alignParentBottom="true"
        />
    </RelativeLayout>
</TabHost>


if you want to place Tabs at top , remove    android:layout_alignParentBottom="true"

https://picasaweb.google.com/115546358500228747299/Jun27201203?authkey=Gv1sRgCLmos6S5s_iaTA&feat=directlink#5836330903891211490

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