Android: How to use onSavedInstanceState.

The Bundle is a container for all the information you want to save. You use the put* functions to insert data into it. Here’s a short list (there are more) of put functions you can use to store data in the Bundle.

putString
putBoolean
putByte
putChar
putFloat
putLong
putShort
putParcelable (used for objects but they must implement Parcelable)

In your onCreate function, this Bundle is handed back to the program. The best way to check if the application is being reloaded, or started for the first time is:

if (savedInstanceState != null) {
    // Then the application is being reloaded
}

To get the data back out, use the get* functions just like the put* functions. The data is stored as a name-value pair. This is like a hashmap. You provide a key and the value, then when you want the value back, you give the key and the function gets the value. Here’s a short example.

@Override
public void onSaveInstanceState(Bundle outState) {
   outState.putString("message", "This is my message to be reloaded");
   super.onSaveInstanceState(outState);
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (savedInstanceState != null) {
        String message = savedInstanceState.getString("message");
        Toast.makeText(this, message, Toast.LENGTH_LONG).show();
    }
}

Your saved message will be toasted to the screen. Hope this helps.

ref: http://stackoverflow.com/questions/6525698/how-to-use-onsavedinstancestate-example-please

Android: Fragment in ViewPager not restored after popBackStack

just change getActivity().getSupportFragmentManager() to getChildFragmentManager() when you init viewPagerAdapter

viewPager = (HeightWrappingViewPager) view.findViewById(R.id.viewpager);
viewPagerAdapter = new CheckListViewPagerAdapter(getChildFragmentManager()); //getActivity().getSupportFragmentManager()
viewPager.setAdapter(viewPagerAdapter);

ref: http://stackoverflow.com/questions/13379194/how-to-add-a-fragment-inside-a-viewpager-using-nested-fragment-android-4-2
https://code.google.com/p/android/issues/detail?id=55068

Android: Get Latitude and Longitude of the mobile device

With google things changes very often: non of the previous answers worked for me.

April 2016

based on this google training here is how you do it using

fused location provider

this requires Set Up Google Play Services

Activity class

 

public class GPSTrackerActivity extends AppCompatActivity implements
    GoogleApiClient.ConnectionCallbacks,     
 GoogleApiClient.OnConnectionFailedListener {

private GoogleApiClient mGoogleApiClient;
Location mLastLocation;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (mGoogleApiClient == null) {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }

}

protected void onStart() {
    mGoogleApiClient.connect();
    super.onStart();
}

protected void onStop() {
    mGoogleApiClient.disconnect();
    super.onStop();
}

@Override
public void onConnected(Bundle bundle) {
    try {

        mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
                mGoogleApiClient);
        if (mLastLocation != null) {
            Intent intent = new Intent();
            intent.putExtra("Longitude", mLastLocation.getLongitude());
            intent.putExtra("Latitude", mLastLocation.getLatitude());
            setResult(1,intent);
            finish();

        }
    } catch (SecurityException e) {

    }

}

@Override
public void onConnectionSuspended(int i) {

}

@Override
public void onConnectionFailed(ConnectionResult connectionResult) {

}
}

usage

in you activity

Intent intent = new Intent(context, GPSTrackerActivity.class);
    startActivityForResult(intent,1);

And this method

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode == 1){
        Bundle extras = data.getExtras();
        Double longitude = extras.getDouble("Longitude");
        Double latitude = extras.getDouble("Latitude");
    }
}

Ref: http://stackoverflow.com/questions/2227292/how-to-get-latitude-and-longitude-of-the-mobile-device-in-android

Android: Read/Write String From A File

Write File:

private void writeToFile(String data,Context context) {
    try {
        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(context.openFileOutput("config.txt", Context.MODE_PRIVATE));
        outputStreamWriter.write(data);
        outputStreamWriter.close();
    }
    catch (IOException e) {
        Log.e("Exception", "File write failed: " + e.toString());
    } 
}

Read File:

private String readFromFile(Context context) {

    String ret = "";

    try {
        InputStream inputStream = context.openFileInput("config.txt");

        if ( inputStream != null ) {
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String receiveString = "";
            StringBuilder stringBuilder = new StringBuilder();

            while ( (receiveString = bufferedReader.readLine()) != null ) {
                stringBuilder.append(receiveString);
            }

            inputStream.close();
            ret = stringBuilder.toString();
        }
    }
    catch (FileNotFoundException e) {
        Log.e("login activity", "File not found: " + e.toString());
    } catch (IOException e) {
        Log.e("login activity", "Can not read file: " + e.toString());
    }

    return ret;
}

Android : Convert String to Date and Date to String

From String to Date

String dtStart = "2010-10-15T09:27:37Z";  
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");  
try {  
    Date date = format.parse(dtStart);  
    System.out.println(date);  
} catch (ParseException e) {  
    // TODO Auto-generated catch block  
    e.printStackTrace();  
}

From Date to String

SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");  
try {  
    Date date = new Date();  
    String datetime = dateFormat.format(date);
    System.out.println("Current Date Time : " + datetime); 
} catch (ParseException e) {  
    // TODO Auto-generated catch block  
    e.printStackTrace();  
}

ที่มา: http://stackoverflow.com/questions/8573250/android-how-can-i-convert-string-to-date

Android: Get complete address from latitude and longitude

ประมาณนี้

Geocoder geocoder;
List<Address> addresses;
geocoder = new Geocoder(this, Locale.getDefault());

addresses = geocoder.getFromLocation(latitude, longitude, 1); // Here 1 represent max location result to returned, by documents it recommended 1 to 5

String address = addresses.get(0).getAddressLine(0); // If any additional address line present than only, check with max available address lines by getMaxAddressLineIndex()
String city = addresses.get(0).getLocality();
String state = addresses.get(0).getAdminArea();
String country = addresses.get(0).getCountryName();
String postalCode = addresses.get(0).getPostalCode();
String knownName = addresses.get(0).getFeatureName(); // Only if available else return NULL

ที่มา : http://stackoverflow.com/questions/9409195/how-to-get-complete-address-from-latitude-and-longitude