How to set a theme to whole application in code, but not in the Manifest?

Question

I know how to set theme to whole application in manifest,but how to set theme to whole application programmatically ? I am trying this: getApplicationContext.se

Answer 1

I spent a lot of time getting this to work and now my app has selectable Light and Dark themes which can even be selected dynamically coming immediately into play including Prefs. Below is the resource I use with some other ideas commented out which I played with at some starge.

The key item here is

true

and that took me a while to realize. My app does some heavy lifting while starting so it was important to not have the mandatory Manifest theme showing before the one I set in onCreate.

To be able to restart the app dynamically I check if this was how the app was started/restarted like this.

SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
boolean useThemeLight = sp.getBoolean("useThemeLight", false);
//Since this Activity can also be started by the Theme Toggle in the Action bar we need to see if
//there is a TOGGLE_THEME extra which only it uses
Intent curIntent = this.getIntent();
if (curIntent.getExtras() != null && curIntent.getExtras().containsKey(TOGGLE_THEME)) {
    if(curIntent.getStringExtra(TOGGLE_THEME).equals("Dark")){
        this.setTheme(R.style.MyAppThemeDark);
        CurrentTheme = "Dark";
    }else{
        this.setTheme(R.style.MyAppThemeLight);
        CurrentTheme = "Light";
    }
    activityThemeToggleActive = true;
} else {
    if (useThemeLight) {
        this.setTheme(R.style.MyAppThemeLight);
        CurrentTheme = "Light";
    } else {
        this.setTheme(R.style.MyAppThemeDark);
        CurrentTheme = "Dark";
    }
}

In Preferences I do this.

SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
boolean useThemeLight = sp.getBoolean("useThemeLight", false);
if (useThemeLight) {
    this.setTheme(R.style.MyAppThemeLight);
} else {
    this.setTheme(R.style.MyAppThemeDark);
}

Hope this gets you started. Regards, John.