Develop Reference

broadCast Receiver is never called

I am trying to detect if the WiFi is connected or not by listening to the "SUPPLICANT_CONNECTION_CHANGE_ACTION" as shown below in the code. But the problem is
when i run the App i receive no notificatio from the broadCast Receiver i am registered to!!
why that is happening and how to solve it?
code:
IntentFilter intentFilter2 = new IntentFilter(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ConnectivityModule();
}
protected void ConnectivityModule() {
// TODO Auto-generated method stub
Log.d(TAG, "#interNetConnectivityModule: called");
registerReceiver(SupplicantReceiver, intentFilter2);
}
BroadcastReceiver SupplicantReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
final String action = intent.getAction();
if (action.equals(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION)) {
SupplicantState supplicantState = (SupplicantState)intent.getParcelableExtra(WifiManager.EXTRA_NEW_STATE);
if (supplicantState == (SupplicantState.COMPLETED)) {
Log.d(TAG, "#SupplicantReceiver: connected");
}
if (supplicantState == (SupplicantState.DISCONNECTED)) {
Log.d(TAG, "#SupplicantReceiver: not connected");
}
}
}
};

Here is Example :
Main Activity
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.content.Intent;
import android.view.View;
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
// broadcast a custom intent.
public void broadcastIntent(View view)
{
Intent intent = new Intent();
intent.setAction("com.tutorialspoint.CUSTOM_INTENT");
sendBroadcast(intent);
}
}
My Broadcast Receiver :
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
public class MyReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "Intent Detected.", Toast.LENGTH_LONG).show();
}
}
This is how you should declare Broadcast Receiver in your Manifest :
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.helloworld"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<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="MyReceiver">
<intent-filter>
<action android:name="com.tutorialspoint.CUSTOM_INTENT">
</action>
</intent-filter>
</receiver>
</application>
</manifest>
Main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button android:id="#+id/btnStartService"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="#string/broadcast_intent"
android:onClick="broadcastIntent"/>
</LinearLayout>

Your receiver looks correctly registered (at runtime, not based on Manifest, but whatever, should be good anyway).
I'm guessing.. have you tried putting logs in onReceive method like
#Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
Log.d(TAG, "Reached this point, receiver is working");
final String action = intent.getAction();
if (action.equals(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION)) {
SupplicantState supplicantState = (SupplicantState)intent.getParcelableExtra(WifiManager.EXTRA_NEW_STATE);
if (supplicantState == (SupplicantState.COMPLETED)) {
Log.d(TAG, "#SupplicantReceiver: connected");
}
if (supplicantState == (SupplicantState.DISCONNECTED)) {
Log.d(TAG, "#SupplicantReceiver: not connected");
}
Log.d(TAG, "Checking for an error in retrieving data!");
boolean myTest = intent.getBooleanExtra(EXTRA_SUPPLICANT_CONNECTED, false);
if (myTest) Log.d(TAG, "This way it worked!");
else Log.d(TAG, "This does not mean it didn't work at all! Might just be the correct value as a DISCONNECTED status");
} else Log.d(TAG, "Bizzarre error, action received was different from the one receiver was registered to! [ " + action + " ] ");
}
My guess is that you might be trying to retrieve the information in a wrong way, and with logs so strictly defined you can't see enough of what happens, but the receiver works fine

I need alarm to start after specified time interval but alarm is executing at the start and repeats after certain interval

I have attached my code here for reference.
I need alarm to be executed after certain interval but its starting at the beginning and repeating. Can i get a solution for this.
AlarmManagerExample.java
package com.example.alarmmanagerexample;
import android.os.Bundle;
import android.os.SystemClock;
import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
public class AlarmManagerExample extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_alarm_manager_example);
try {
//Create a new PendingIntent and add it to the AlarmManager
Intent intent = new Intent(this, RingAlarm.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this,
12345, intent, PendingIntent.FLAG_CANCEL_CURRENT);
AlarmManager am =
(AlarmManager)getSystemService(Activity.ALARM_SERVICE);
am.setRepeating(AlarmManager.ELAPSED_REALTIME, SystemClock.elapsedRealtime(),
2*60*60,pendingIntent);
} catch (Exception e) {}
}
}
activity_alarm_manager_example.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".AlarmManagerExample" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="#string/hello_world" />
</RelativeLayout>
RingAlarm.java
package com.example.alarmmanagerexample;
import android.app.Activity;
import android.content.Context;
import android.media.MediaPlayer;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
public class RingAlarm extends Activity {
MediaPlayer mp=null ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.alarm);
Button stopAlarm = (Button) findViewById(R.id.stopAlarm);
mp = MediaPlayer.create(getBaseContext(),R.raw.audio);
stopAlarm.setOnTouchListener(new OnTouchListener() {
#Override
public boolean onTouch(View arg0, MotionEvent arg1) {
// TODO Auto-generated method stub
mp.stop();
finish();
return false;
}
});
playSound(this, getAlarmUri());
}
private void playSound(final Context context, Uri alert) {
Thread background = new Thread(new Runnable() {
public void run() {
try {
mp.start();
} catch (Throwable t) {
Log.i("Animation", "Thread exception "+t);
}
}
});
background.start();
}
#Override
protected void onDestroy() {
super.onDestroy();
mp.stop();
} //Get an alarm sound. Try for an alarm. If none set, try notification,
//Otherwise, ringtone.
private Uri getAlarmUri() {
Uri alert = RingtoneManager
.getDefaultUri(RingtoneManager.TYPE_ALARM);
if (alert == null) {
alert = RingtoneManager
.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
if (alert == null) {
alert = RingtoneManager
.getDefaultUri(RingtoneManager.TYPE_RINGTONE);
}
}
return alert;
}
}
Alarm.xml
<?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:text="Stop Alarm" android:id="#+id/stopAlarm"
android:layout_width="wrap_content" android:layout_height="wrap_content" />
</LinearLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.alarmmanagerexample"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.alarmmanagerexample.AlarmManagerExample"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".RingAlarm"
android:label="#string/app_name" />
</application>
</manifest>

i can't redirect to next registration page when i click on to SIGN IN button

basically am a java developer but now am developing an android app.In my app i can't redirect to the next page when i click on to SIGN IN button and here is my code
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;
public class MainActivity extends ActionBarActivity implements View.OnClickListener {
Button log,sign;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
log = (Button) findViewById(R.id.login);
sign = (Button) findViewById(R.id.signup);
log.setOnClickListener(this);
sign.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch(v.getId()) {
case R.id.login:
break;
case R.id.signup:
Intent open = new Intent("com.example.eblood.Register");
startActivity(open);
break;
}
}
}
}
Here is my next page java code
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class Register extends Activity{
Button backlog,regg;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.register);
backlog = (Button) findViewById(R.id.linktologin);
regg = (Button) findViewById(R.id.register);
backlog.setOnClickListener((OnClickListener) this);
}
public void onClick (View v)
{
switch(v.getId()) {
case R.id.register:
break;
case R.id.linktologin:
Intent in = new Intent("com.example.eblood.MainActivity");
startActivity(in);
break;
}
}
}
Here is my manifest code.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.eblood"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.eblood.home"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.example.eblood.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="com.example.eblood.MAINACTIVITY" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
android:name="com.example.eblood.Register"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.REGISTER" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
and the error am getting is android.content.ActivityNotFoundException: No Activity found to handle Intent { act=com.example.eblood.Register }
And here is my home.java
package com.example.eblood;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class home extends Activity {
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);
Thread timer = new Thread(){
public void run(){
try{
sleep(2000);
} catch (InterruptedException e){
e.printStackTrace();
} finally {
Intent openMainActivity = new Intent("com.example.eblood.MAINACTIVITY");
startActivity(openMainActivity);
}
}
};
timer.start();}{
}
}

Try this..
If you use Intent open = new Intent("com.example.eblood.Register"); you will get ActivityNotFoundException change it as Intent open = new Intent(MainActivity.this,Register.class);
Change this
Intent open = new Intent("com.example.eblood.Register");
startActivity(open);
to
Intent open = new Intent(MainActivity.this,Register.class);
startActivity(open);
also
change this
Intent in = new Intent("com.example.eblood.MainActivity");
startActivity(in);
to
Intent in = new Intent(Register.this,MainActivity.class);
startActivity(in);
EDIT
Change this.
Intent openMainActivity = new Intent("com.example.eblood.MAINACTIVITY");
startActivity(openMainActivity);
to
Intent openMainActivity = new Intent(home.this,MainActivity.class);
startActivity(openMainActivity);

Discovering Bluetooth Devices: ListView will not get updated

I am trying to discover Bluetooth Devices.
When I'm debugging my adapter gets filled, but my listview wount refresh, I am seeing just a blank site.
here is my code:
package com.example.elevator;
import java.util.Set;
import android.os.Bundle;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.view.Menu;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends Activity
{
private static final int REQUEST_ENABLE_BT = 1;
private BluetoothAdapter mBluetoothAdapter = null;
private ArrayAdapter<String> mNewDevicesArrayAdapter;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNewDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.activity_main);
ListView newDevicesListView = (ListView) findViewById(R.id.new_devices);
newDevicesListView.setAdapter(mNewDevicesArrayAdapter);
// newDevicesListView.setOnItemClickListener(mDeviceClickListener);
// Register for broadcasts when a device is discovered
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
this.registerReceiver(mReceiver, filter);
filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.registerReceiver(mReceiver, filter);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
}
#Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void onClickbtnActivateBluetooth(View view)
{
if (mBluetoothAdapter == null)
{
Toast.makeText(this, "Bluetooth ist nicht verfügbar!", Toast.LENGTH_LONG).show();
finish();
return;
}
else if (!mBluetoothAdapter.isEnabled())
{
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
Toast.makeText(this, "Bluetooth wurde aktiviert!", Toast.LENGTH_LONG).show();
findViewById(R.id.btnSearchDevices).setEnabled(true);
}
public void onClickbtnSearchDevices(View view)
{
mBluetoothAdapter.startDiscovery();
Toast.makeText(this, "Bluetooth Geräte werden gesucht!", Toast.LENGTH_LONG).show();
// Find and set up the ListView for newly discovered devices
}
// Create a BroadcastReceiver for ACTION_FOUND
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// If it's already paired, skip it, because it's been listed already
if (device.getBondState() != BluetoothDevice.BOND_BONDED)
{
mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());
mNewDevicesArrayAdapter.notifyDataSetChanged();
}
}
}
};
}
the activity:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="#+id/btnSearchDevices"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/btnEnableBT"
android:layout_alignRight="#+id/btnEnableBT"
android:layout_below="#+id/btnEnableBT"
android:enabled="false"
android:onClick="onClickbtnSearchDevices"
android:text="Geräte suchen" />
<Button
android:id="#+id/btnEnableBT"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:onClick="onClickbtnActivateBluetooth"
android:text="Enable Bluetooth" />
<ListView
android:id="#+id/new_devices"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_below="#+id/btnSearchDevices" >
</ListView>
</RelativeLayout>
the manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.elevator"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="16" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.SET_DEBUG_APP"/>
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.elevator.MainActivity"
android:label="#string/app_name" >
android:debuggable="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
I hope you can help me!

You have to pass the list as a constructor argument.
mNewDevicesArrayAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,devicesList);

Instead of
mNewDevicesArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1);
you may also try this.
mNewDevicesArrayAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,0);
After that your list view will be updated each time you discover a new device using:
mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());

how to start the app on power button press

I want to start my app when a user press the power button. I m following This code
but its not showing any Log and toast.
here is my complete code.
MyReceiver.java
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.widget.Toast;
public class MyReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
Log.v("onReceive", "Power button is pressed.");
Toast.makeText(context, "power button clicked", Toast.LENGTH_LONG)
.show();
// perform what you want here
}
}
menifest File
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.powerbuttontest"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.powerbuttontest.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=".MyReceiver" >
<intent-filter>
<action android:name="android.intent.action.SCREEN_OFF" >
</action>
<action android:name="android.intent.action.SCREEN_ON" >
</action>
<action android:name="android.intent.action.ACTION_POWER_CONNECTED" >
</action>
<action android:name="android.intent.action.ACTION_POWER_DISCONNECTED" >
</action>
<action android:name="android.intent.action.ACTION_SHUTDOWN" >
</action>
</intent-filter>
</receiver>
</application>
</manifest>
MainActivity.java
package com.example.powerbuttontest;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
I think i m committing a mistake in my menifest file. please have a look on this. thanks.

First, unlike other broad casted intents, for Intent.ACTION_SCREEN_OFF and Intent.ACTION_SCREEN_ON you CANNOT declare them in your Android Manifest! so You need to make a service which will keep on running like this
public static class UpdateService extends Service {
#Override
public void onCreate() {
super.onCreate();
// register receiver that handles screen on and screen off logic
IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
BroadcastReceiver mReceiver = new Receiver();
registerReceiver(mReceiver, filter);
}
#Override
public void onStart(Intent intent, int startId) {
boolean screenOn = intent.getBooleanExtra("screen_state", false);
if (!screenOn) {
// your code
} else {
// your code
}
}
}
and your receiver can be something
public class Receiver extends BroadcastReceiver {
private boolean screenOff;
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
screenOff = true;
} else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
screenOff = false;
}
Intent i = new Intent(context, UpdateService.class);
i.putExtra("screen_state", screenOff);
context.startService(i);
}
}

Here is my complete code. Hope this helps. I was basically making a look screen app. This will disable your default lock screen. and on power button press it will start a service and runs to look for power button press event.
Layout.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<Button
android:id="#+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="#+id/toggleButton1"
android:layout_marginTop="72dp"
android:enabled="false"
android:text="Settings" />
<ToggleButton
android:id="#+id/toggleButton1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="72dp"
android:checked="true"
android:textOff="Disable"
android:textOn="Enable" />
</RelativeLayout>
MainActivity.java
package com.example.powerbuttontest;
import android.app.Activity;
import android.app.KeyguardManager;
import android.app.KeyguardManager.KeyguardLock;
import android.content.Context;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import android.widget.ToggleButton;
public class MainActivity extends Activity {
ToggleButton btnToggleLock;
Button btnMisc;
Toast toast;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnMisc = (Button) findViewById(R.id.button1);
btnToggleLock = (ToggleButton) findViewById(R.id.toggleButton1);
toast = Toast.makeText(getApplicationContext(), "", Toast.LENGTH_SHORT);
btnToggleLock.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
if (btnToggleLock.isChecked()) {
toast.cancel();
toast.setText("Unlocked");
toast.show();
Log.i("Unlocked", "If");
Context context = getApplicationContext();
KeyguardManager _guard = (KeyguardManager) context
.getSystemService(Context.KEYGUARD_SERVICE);
KeyguardLock _keyguardLock = _guard
.newKeyguardLock("KeyguardLockWrapper");
_keyguardLock.disableKeyguard();
MainActivity.this.startService(new Intent(
MainActivity.this, UpdateService.class));
} else {
toast.cancel();
toast.setText("Locked");
toast.show();
Context context = getApplicationContext();
KeyguardManager _guard = (KeyguardManager) context
.getSystemService(Context.KEYGUARD_SERVICE);
KeyguardLock _keyguardLock = _guard
.newKeyguardLock("KeyguardLockWrapper");
_keyguardLock.reenableKeyguard();
Log.i("Locked", "else");
MainActivity.this.stopService(new Intent(MainActivity.this,
UpdateService.class));
}
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
// TODO Auto-generated method stub
super.onConfigurationChanged(newConfig);
Log.i("onConfigurationChanged", "Called");
}
}
MyReciever.java
package com.example.powerbuttontest;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.widget.Toast;
public class MyReceiver extends BroadcastReceiver {
private boolean screenOff;
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
screenOff = true;
} else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
screenOff = false;
}
Intent i = new Intent(context, UpdateService.class);
i.putExtra("screen_state", screenOff);
context.startService(i);
}
}
UpdateService.java
package com.example.powerbuttontest;
import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;
public class UpdateService extends Service {
BroadcastReceiver mReceiver;
#Override
public void onCreate() {
super.onCreate();
// register receiver that handles screen on and screen off logic
IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
mReceiver = new MyReceiver();
registerReceiver(mReceiver, filter);
}
#Override
public void onDestroy() {
unregisterReceiver(mReceiver);
Log.i("onDestroy Reciever", "Called");
super.onDestroy();
}
#Override
public void onStart(Intent intent, int startId) {
boolean screenOn = intent.getBooleanExtra("screen_state", false);
if (!screenOn) {
Log.i("screenON", "Called");
Toast.makeText(getApplicationContext(), "Awake", Toast.LENGTH_LONG)
.show();
} else {
Log.i("screenOFF", "Called");
// Toast.makeText(getApplicationContext(), "Sleep",
// Toast.LENGTH_LONG)
// .show();
}
}
#Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return null;
}
}
Menifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.powerbuttontest"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.DISABLE_KEYGUARD"/>
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
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=".MyReceiver" />
<service android:name=".UpdateService" />
</application>
</manifest>

Here this one is the complete code, which will open your application as soon you presss power button. I am also doing the same project, where i want to open my Application directly after i press power button (turn on).
MainActivity.java
public class MainActivity extends Activity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_switch_power_offon);
startService(new Intent(getApplicationContext(), LockService.class));
}//EOF Oncreate
}//EOF Activity
LockService.java
public class LockService extends Service {
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public void onCreate() {
super.onCreate();
}
#Override
public int onStartCommand(Intent intent, int flags, int startId)
{
final IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
filter.addAction(Intent.ACTION_USER_PRESENT);
final BroadcastReceiver mReceiver = new ScreenReceiver();
registerReceiver(mReceiver, filter);
return super.onStartCommand(intent, flags, startId);
}
public class LocalBinder extends Binder
{
LockService getService() {
return LockService.this;
}
}//EOF SERVICE
ScreenReceiver.java
public class ScreenReceiver extends BroadcastReceiver {
public static boolean wasScreenOn = true;
public void onReceive(final Context context, final Intent intent) {
Log.e("LOB","onReceive");
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF))
{
// do whatever you need to do here
wasScreenOn = false;
//Log.e("LOB","wasScreenOn"+wasScreenOn);
Log.e("Screen ","shutdown now");
}
else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON))
{
// and do whatever you need to do here
wasScreenOn = true;
Log.e("Screen ","awaked now");
Intent i = new Intent(context, MainActivity.class); //MyActivity can be anything which you want to start on bootup...
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(i);
}
else if(intent.getAction().equals(Intent.ACTION_USER_PRESENT))
{
Log.e("LOB","userpresent");
// Log.e("LOB","wasScreenOn"+wasScreenOn);
}
}
}//EOF SCREENRECEIVER.JAVA
Now this is xml file, Please copy paste and just change the package name you are using
<?xml version="1.0" encoding="utf-8"?>
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.userpresent.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>
<service android:name="com.example.userpresent.LockService" >
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</service>
</application>