github: S06.01-LaunchSettingsActivity , S06.02-SettingsFragment , 

S06.03-PolishingPreferences

Settings for Sunshine:

1. Unit Setting-
   • Fahrenheit  
   • Celsius
2. Location Setting 

* Reference: Udacity Nanodegree Program- Become an Android Developer *

public class SettingsActivity extends AppCompatActivity {
    // TODO (1) Add new Activity called SettingsActivity using Android Studio wizard

<!--TODO (２) Add a Settings option to the main menu-->
<item
    android:id= "@+id/action_settings"
    android:orderInCategory="2"
    android:title="@string/action_setting"
    app:showAsAction="never"/>

    // TODO (３) Launch SettingsActivity when the Settings option is clicked

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if(id == R.id.action_settings){
            Intent startSettingsActivity = new Intent(this, SettingsActivity.class);
            startActivity(startSettingsActivity);
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.setContentView(R.layout.activity_settings);

    // TODO (4.1) Set setDisplayHomeAsUpEnabled to true on the support ActionBar
    this.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}

// TODO (4.2) Add Up Button on SettingsActivity
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();
    if(id == android.R.id.home){
        onBackPressed();
    }
    return super.onOptionsItemSelected(item);
}

<!-- TODO (5) Change MainActivity's launch mode to singleTop -->
<activity
    android:name=".MainActivity"
    android:label="@string/app_name"
    android:launchMode="singleTop">