Android - How to inject a values/strings.xml in runtime

String resources are static defined and can not be changed at runtime.

However, you could use the Restring library to set and load strings at runtime by adding the dependencies:

// Replace bundled strings dynamically
implementation 'dev.b3nedikt.restring:restring:4.0.3'

// Intercept view inflation
implementation 'io.github.inflationx:viewpump:2.0.3'

// Allows to update the text of views at runtime without recreating the activity
implementation 'dev.b3nedikt.reword:reword:1.1.0'

Initialising it in your Application class:

Restring.init(this,
        new RestringConfig.Builder()
                .stringsLoader(new SampleStringsLoader())
                .loadAsync(false) // If string loader should load strings asynchronously, default true
                .build()
        );

ViewPump.init(ViewPump.builder()
        .addInterceptor(RewordInterceptor.INSTANCE)
        .build());

Then it should be injected into context:

@Override
protected void attachBaseContext(Context newBase) {
    super.attachBaseContext(ViewPumpContextWrapper.wrap(Restring.wrapContext(newBase)));
}

@Override
public Resources getResources() {
    return Restring.wrapContext(getBaseContext()).getResources();
}

And you can load more strings at any time:

// e.g. locale=Locale.EN newStrings=map of (key-value)s
Restring.setStrings(locale, newStrings);

And apply updated resources without restarting the app:

// The layout containing the views you want to localise
final View rootView = getWindow().getDecorView().findViewById(android.R.id.content);
Reword.reword(rootView);

More details: https://github.com/B3nedikt/restring