Change and apply theme at runtime in Android

Question

Possible Duplicate:
How to change current Theme at runtime in Android

I have an Android application where I allow users to switch between themes at runtime. Switching a theme is easy but the theme isn't applied until the activity is recreated. I found a way to apply the theme to current activity but if the user presses back button previous screens still have the old theme. How can I change theme for those activities? Example of app that supports it: Tasks Free

Answer 1

Just a hint I suppose:

Before finish(); Call

setResult(AnIntegerThatNotifiesThePreviousActivitiesToChangeTheme);

Now in all your Activities, implement onActivityResult

protected void onActivityResult(int request, int result, Intent data) {
    if(result == AnIntegerThatNotifiesThePreviousActivitiesToChangeTheme)
    {
        //update the current theme
    }
}

---

Another solution (Better):

Implement a class that saves the theme:

public class CurrentThemeHolder {
    private CurrentThemeHolder() {
    }
    private static instance;
    public static getInstance() {
        if(instance == null)
            return new CurrentThemeHolder();
        else
            return instance;
    }
    private int mTheme; //identifier of the theme
    public getTheme() {
        return mTheme;
    }
    public setTheme(int newTheme){
        mTheme = newTheme;
    }
}

Now let all ur activities extend this ThemeActivity:

public class ThemeActivity extends Activity {
    private int mTheme;
    protected void onResume() {
        if(mTheme != CurrentThemeHolder.getInstance().getTheme()) {
            //do what you should do to set the theme
            mTheme = CurrentThemeHolder.getInstance().getTheme();
            //everytime you set the theme save it
            //this maybe should be done in onCreate()
        }
    }
}