is it possible to hide the system bar

I created a launcher, to use it in an internal application. for some security reasons i would like to hide the system bar (the acces to the parameter an ordrer to the acces to installed application). But i have no idea how to do this. Tablet that will be used are not rooted. Can you help me please?

You can't hide it but you can disable it, except home. For that you can give your application as home category and let the user choose.

<category android:name="android.intent.category.HOME" />

Rest all can be disable.

add this in manifest.

<uses-permission android:name="android.permission.EXPAND_STATUS_BAR"/>

inside onCreate()

this.requestWindowFeature(Window.FEATURE_NO_TITLE); 
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.activity_home);
    View v = findViewById(R.id.home_view);
    v.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE);

where home_view is the parent view of xml file.

 @Override
     public boolean onKeyDown(int keyCode, KeyEvent event) {
            return false;
        }

 public void onWindowFocusChanged(boolean hasFocus)
     {
             try
             {
                if(!hasFocus)
                {
                     Object service  = getSystemService("statusbar");
                     Class<?> statusbarManager = Class.forName("android.app.StatusBarManager");
                     Method collapse = statusbarManager.getMethod("collapse");
                     collapse .setAccessible(true);
                     collapse .invoke(service);
                }
             }
             catch(Exception ex)
             {
             }
     }

You can hide the bottom bar I used this code to hide:

getWindow().getDecorView().setSystemUiVisibility(View.GONE);

use this code for android box with keyboard or remote.

Tablet that will be used are not rooted

Then you can't hide it. You can however use SYSTEM_UI_FLAG_HIDE_NAVIGATION to hide it temporary, but it will get visible once the user touches the screen:

There is a limitation: because navigation controls are so important, the least user interaction will cause them to reappear immediately. When this happens, both this flag and SYSTEM_UI_FLAG_FULLSCREEN will be cleared automatically, so that both elements reappear at the same time.