How change the background of all activities?

Question

I will also try this :

public Button button;  
public View background;

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

    button = (Button)findViewById(R.id.color);
    background = findViewById(R.id.colorBackg);

    button.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view) {
            int colorCreat = Color.rgb(255, 255, 255);
            background.setBackgroundColor(colorCreat);
        }
    });

}

It works but when I change the activity the color resets. How I can change the color of all background permanently ? Thanks.

Answer 1

Create a style under styles.xml in res directory of your project

<resources xmlns:tools="http://schemas.android.com/tools">

   <!-- Base application theme. -->
    <style name="app_theme" parent="Theme.AppCompat.NoActionBar">
        <item name="android:windowBackground">@android:color/black</item>
    </style>

</resources>

The above theme can then be applied to you application element in manifest like this

<application
 android:theme="@style/Theme.Activity.Default"/>

So this implies all the activity will inherit the above style declared in Application tag, unless any individual Activity overrides it specifying some other style.

Hope it helps.

Answer 2

As already answered by Mayank Bhatnagar , you should create an style inside the styles.xml file. See the guide for detailed implementation.

---

If you want to be able to dynamically change the theme, I recommend you to use a Settings to define which them to use. And then in your activities to listen to preference change.

First create a Listener to preference change, that will react to style change.

public class StylePreferenceChangeListener implements OnSharedPreferenceChangeListener {

    //String constant used as ID to the style preference (used here and in SettingActivity)
    public static String PREFERENCE_STYLE_ID = "preference.style";

    //The activity that we want to modify style
    private Activity activity;

    public StylePreferenceChangeListener(Activity activity) {
        super();
        this.activity = activity;
    }

    // listener implementation
    public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
        if(PREFERENCE_STYLE_ID.equals(key)) {
            int newStyleId = prefs.getInt(key, R.style.default_style);
            activity.getTheme.applyStyle(newStyleId, true);
    }

}

And in your activity, create an instance of this Listener. And register/unregister it inside onResume()/onPause().

public class myActivity extends Activity {

    //Our listener reference
    StylePreferenceChangeListener myListener;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate();
        setContentView(R.layout.myactivity);
        //create instance now so we are sure the activity exist
        myListener = new StylePreferenceChangeListener(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        //register our listener
        getSharedPreferences().registerOnSharedPreferenceChangeListener(myListener);
    }

    protected void onPause() {
        super.onPause();
        //unregister our listener
        getSharedPreferences().unregisterOnSharedPreferenceChangeListener(myListener);
    }

    protected void onDestroy() {
        super.onDestroy();
        //The activity is meant to be destroy, makes no sense to keep our listener
        //Drop his reference to allow garbage collecting
        myListener = null;
    }

}