Changement d'une application android version 2.3 d'android 4.2

Mon code fonctionne sous Android version 2.3. Que dois-je modifier dans le code pour qu'il fonctionne en version 4.2 et plus ainsi?

Mon code,

    public class GPSTracker extends Service implements LocationListener {
private final Context mContext;
//flag for GPS status
boolean isGPSEnabled = false;
//flag for network status
boolean isNetworkEnabled = false;
//flag for GPS status
boolean canGetLocation = false;
Location location; //location
double latitude; //latitude
double longitude; //longitude
//The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; //10 meters
//The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; //1 minute
//Declaring a Location Manager
protected LocationManager locationManager;
public GPSTracker(Context context) {
this.mContext = context;
getLocation();
}
public Location getLocation() {
try {
locationManager = (LocationManager) mContext
.getSystemService(LOCATION_SERVICE);
//getting GPS status
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
//getting network status
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled) {
//no network provider is enabled
} else {
this.canGetLocation = true;
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager .NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
//if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
/**
* Stop using GPS listener
* Calling this function will stop using GPS in your app
* */
public void stopUsingGPS(){
if(locationManager != null){
locationManager.removeUpdates(GPSTracker.this);
}       
}
/**
* Function to get latitude
* */
public double getLatitude(){
if(location != null){
latitude = location.getLatitude();
}
//return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude(){
if(location != null){
longitude = location.getLongitude();
}
//return longitude
return longitude;
}
/**
* Function to check GPS/wifi enabled
* @return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog
* On pressing Settings button will lauch Settings Options
* */
public void showSettingsAlert(){
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
//Setting Dialog Title
alertDialog.setTitle("GPS is settings");
//Setting Dialog Message
alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
//On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
//on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
//Showing Alert Message
alertDialog.show();
}
@Override
public void onLocationChanged(Location location) {
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public IBinder onBind(Intent arg0) {
return null;
}
}

Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.safetymobile"
android:versionCode="2"
android:versionName="1.2" >
<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CALL_PHONE" >
</uses-permission>
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" >
</uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" >
</uses-permission>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.VIBRATE" >
</uses-permission>
<uses-permission android:name="android.permission.WAKE_LOCK" >
</uses-permission>
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"></uses-permission>
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.SEND_SMS" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.safetymobile.MainActivity"
android:label="@string/app_name" 
android:theme="@android:style/Theme.Light.NoTitleBar.Fullscreen"
android:clearTaskOnLaunch="true"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.example.safetymobile.ContactList"
android:label="@string/title_activity_contact_list" >
</activity>
<activity
android:name="com.example.safetymobile.Change_setting"
android:label="@string/title_activity_change_setting"
android:clearTaskOnLaunch="true" >
</activity>
<activity
android:name="com.example.safetymobile.CallContent"
android:label="@string/title_activity_call_content"
android:theme="@android:style/Theme.Light.NoTitleBar.Fullscreen" >
</activity>
<activity
android:name="com.example.safetymobile.SMS"
android:label="@string/title_activity_sms"
android:theme="@android:style/Theme.Light.NoTitleBar.Fullscreen" >
</activity>
<activity
android:name="com.example.safetymobile.Alication_list"
android:label="@string/title_activity_alication_list"  >
</activity>
<activity
android:name="com.example.safetymobile.Apps"
android:label="@string/title_activity_apps" 
android:theme="@android:style/Theme.Light.NoTitleBar.Fullscreen">
</activity>
<activity
android:name="com.example.safetymobile.Pass"
android:label="@string/title_activity_pass" >
</activity>
<activity
android:name="com.example.safetymobile.ChangePass"
android:label="@string/title_activity_change_pass" >
</activity>
<activity
android:name="com.example.safetymobile.GPS"
android:label="@string/title_activity_gps" >
</activity>
<activity
android:name="com.example.safetymobile.LightActivity"
android:label="@string/title_activity_light"
android:theme="@android:style/Theme.Light.NoTitleBar.Fullscreen" >
</activity>
<receiver android:name=".StartupActivity">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED"></action>
<category android:name="android.intent.category.DEFAULT"></category>
</intent-filter>
</receiver>
</application>
</manifest>

LogCat :

10-30 09:37:31.816: E/AndroidRuntime(1260): FATAL EXCEPTION: main
10-30 09:37:31.816: E/AndroidRuntime(1260): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.safetymobile/com.example.safetymobile.MainActivity}: java.lang.NullPointerException
10-30 09:37:31.816: E/AndroidRuntime(1260):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at android.os.Handler.dispatchMessage(Handler.java:99)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at android.app.ActivityThread.main(ActivityThread.java:5041)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at java.lang.reflect.Method.invokeNative(Native Method)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at java.lang.reflect.Method.invoke(Method.java:511)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at dalvik.system.NativeStart.main(Native Method)
10-30 09:37:31.816: E/AndroidRuntime(1260): Caused by: java.lang.NullPointerException
10-30 09:37:31.816: E/AndroidRuntime(1260):  at com.example.safetymobile.MainActivity.onCreate(MainActivity.java:123)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at android.app.Activity.performCreate(Activity.java:5104)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
10-30 09:37:31.816: E/AndroidRuntime(1260):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)

Comment faire pour modifier une application android version 2.3, 4.2?

je suis en utilisant eclipse ADT

onCreate partie de MainActivity

gps = new GPSTracker(MainActivity.this);
//check if GPS enabled  
if(gps.canGetLocation())
{
latitude = gps.getLatitude();
longitude = gps.getLongitude();
}
else{
//can't get location
//GPS or Network is not enabled
//Ask user to enable GPS/network in settings
gps.showSettingsAlert();
}
ImageButton btn=(ImageButton)findViewById(R.id.application);
btn.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
Intent t = new Intent(v.getContext(),Apps.class);
startActivity(call);
}
});
mp2 = MediaPlayer.create(this,R.drawable.emsound);
button = (Button) findViewById(R.id.buttonFlashlight);
button1 = (Button) findViewById(R.id.panic);
final Context context = this;
@SuppressWarnings("unused")
final SensorManager mSensorManager;
final PowerManager mPowerManager;
final WindowManager mWindowManager;
final WakeLock mWakeLock;
//Get an instance of the SensorManager
mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
//Get an instance of the PowerManager
mPowerManager = (PowerManager) getSystemService(POWER_SERVICE);
//Get an instance of the WindowManager
mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
mWindowManager.getDefaultDisplay();
//Create a bright wake lock
mWakeLock = mPowerManager.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK, getClass()
.getName());
PackageManager pm = context.getPackageManager();
/*-----------check if camera is available----------*/
if(!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA))
{
@SuppressWarnings("unused")
Logger message;
Log.e("err", "Device has no camera!");
Toast.makeText(getApplicationContext(),
"Your device doesn't have camera!",Toast.LENGTH_SHORT).show();
return;
}
camera = Camera.open();
p = camera.getParameters();
button.setOnClickListener(new OnClickListener() 
{
public void onClick(View v) 
{
if (isFlashOn) {
Toast.makeText(getApplicationContext(), "torch is turned off!", Toast.LENGTH_SHORT).show();
Log.i("info", "torch is turned off!"); 
/*----------- if camera flash is available----------*/
if(context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH))
{
p.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(p);    
//button.setsetText("Torch-ON");
}
/*----------- if camera flash is not available----------*/
else
{
//Toast.makeText(getApplicationContext(), "flash is turned off!", Toast.LENGTH_SHORT).show();
WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = -1;
getWindow().setAttributes(params);
mWakeLock.release();
}
isFlashOn = false;
} 
else 
{
Toast.makeText(getApplicationContext(), "torch is turned on!", Toast.LENGTH_SHORT).show();
Log.i("info", "torch is turned on!");
/*----------- if camera flash is available----------*/
if(context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH))
{
p.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(p);
}
/*----------- if camera flash is not available----------*/
else
{
//Toast.makeText(getApplicationContext(), "flash is turned off!", Toast.LENGTH_SHORT).show();
/* mWakeLock.acquire();
WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = 1.0f;
getWindow().setAttributes(params);*/
DoToLight();
}
isFlashOn = true;
//button.setText("Torch-OFF");
}
}
});