将背景图像更改为android studio中的主题更改

Question

I want to change the theme of my app by a switch button. There is no problem and the theme changes into dark or light as I hit the button. on the other hand, I want to change the background image as the theme changes in different activities. I mean the MainActivity has an image background and other activities have their own background image. I would be very grateful if there is a guy to help me.

this is my code:

private Switch mySwitch;
@Override
protected void onCreate(Bundle savedInstanceState) {
if(AppCompatDelegate.getDefaultNightMode() == 
AppCompatDelegate.MODE_NIGHT_YES){
        setTheme(R.style.darkTheme);
}
else {setTheme(R.style.AppTheme);
}
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

mySwitch = (Switch) findViewById(R.id.my_switch);
if(AppCompatDelegate.getDefaultNightMode() == 
AppCompatDelegate.MODE_NIGHT_YES){
mySwitch.setChecked(true);
}else {
}

mySwitch.setOnCheckedChangeListener(new 
CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton compoundButton, boolean b) 
{
if(b){AppCompatDelegate.setDefaultNightMode 
(AppCompatDelegate.MODE_NIGHT_YES);
restartApp();
}
else {

AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
restartApp();
}
}
});
}

public void restartApp(){
Intent i = new Intent(getApplicationContext(), MainActivity.class);
startActivity(i);
finish();
}
}

Answer 1

Saving content in sharedPref

private SharedPreferences mSharedPreferences;

public SharedCache(SharedPreferences sharedPreferences) {
    mSharedPreferences = sharedPreferences;
}

public String getThemeName() {
    return mSharedPreferences.getString(THEME_NAME, APP_DARK);
}

public void setThemeName(@NonNull String theme) {
    mSharedPreferences.edit().putString(THEME_NAME, theme).apply();
}

Here AppDark is my current theme name , you can set your theme name onChange of your theme .

In Activity onCreate method , get the theme from sharedPref . Or you can follow the below link for better understanding on sharedPreference . https://medium.com/android-grid/android-sharedpreferences-example-writing-and-reading-values-7a677f4448c3