Activity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_layout);
	
    // fixing portrait mode problem for SDK 26 if using windowIsTranslucent = true
    if (Build.VERSION.SDK_INT == 26) {
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
    } else {
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
    }        
}