code: package freed.utils;
  
  import android.os.Build;
  import android.view.View;
  import android.view.Window;
  import android.view.WindowManager;
  
  public class HideNavBarHelper
  {
      private final int hideflags = View.SYSTEM_UI_FLAG_LAYOUT_STABLE
              | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
              | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
              | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
              | View.SYSTEM_UI_FLAG_FULLSCREEN
              | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
  
      private final int showflags = View.SYSTEM_UI_FLAG_VISIBLE;
  
  
  
      public void HIDENAVBAR(Window window)
      {
          if (Build.VERSION.SDK_INT < 16) {
              window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                      WindowManager.LayoutParams.FLAG_FULLSCREEN);
  
          }
          else
          {
              //HIDE nav and action bar
              View decorView = window.getDecorView();
              decorView.setSystemUiVisibility(hideflags);
              decorView.setOnSystemUiVisibilityChangeListener(visibility -> {
                  if (visibility > 0) {
                      if (Build.VERSION.SDK_INT >= 16)
                          window.getDecorView().setSystemUiVisibility(hideflags);
                  }
              });
          }
      }
  
      public void showNavbar(Window window)
      {
          if (Build.VERSION.SDK_INT < 16) {
              window.clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
          }
          else
          {
              //HIDE nav and action bar
              View decorView = window.getDecorView();
              decorView.setSystemUiVisibility(showflags);
              decorView.setOnSystemUiVisibilityChangeListener(visibility -> {
                  if (visibility > 0) {
                      if (Build.VERSION.SDK_INT >= 16)
                          window.getDecorView().setSystemUiVisibility(showflags);
                  }
              });
          }
      }
  }
  