Prevent back button exit on devices with softkey

Android 4.4 now uses sticky immersive mode

app/src/main/java/id/psw/nope/Nope.java

@@ -1,16 +1,21 @@
 package id.psw.nope;
 
 import android.app.Activity;
+import android.os.Build;
 import android.os.Bundle;
 import android.util.Log;
+import android.view.KeyCharacterMap;
+import android.view.KeyEvent;
+import android.view.View;
 import android.view.Window;
 import android.view.WindowManager;
 
 import java.util.Calendar;
 
 public class Nope extends Activity {
 
-    private boolean isDebug = false;
+    private final boolean isDebug = false;
+    private boolean usesSoftkey = true;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -19,6 +24,16 @@ protected void onCreate(Bundle savedInstanceState) {
         setContentView(new NopeView(this));
         makeFullScreen();
         if(isDebug) writeLoadTime();
+        usesSoftkey = checkSoftkey();
+    }
+
+    protected boolean checkSoftkey(){
+        if(Build.VERSION.SDK_INT >= 3){
+            int id = getResources().getIdentifier("config_showNavigationBar", "bool", "android");
+            return id > 0 && getResources().getBoolean(id);
+        }else{
+            return false;
+        }
     }
 
     protected static Boolean isNight(){
@@ -36,10 +51,16 @@ public void makeNoTitle(){
     }
 
     public void makeFullScreen(){
-        getWindow().setFlags(
-                WindowManager.LayoutParams.FLAG_FULLSCREEN,
-                WindowManager.LayoutParams.FLAG_FULLSCREEN
-        );
+        if(Build.VERSION.SDK_INT >= 19){
+            getWindow().getDecorView().setSystemUiVisibility(
+                    View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY | 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
+            );
+        }else{
+            getWindow().setFlags(
+                    WindowManager.LayoutParams.FLAG_FULLSCREEN,
+                    WindowManager.LayoutParams.FLAG_FULLSCREEN
+            );
+        }
     }
 
     @Override
@@ -53,4 +74,16 @@ protected void onResume() {
         super.onResume();
         makeFullScreen();
     }
+
+    // Exit on back keypress only possible when the device has hardware back key
+    // Since you may accidentally pressed soft back key when using this app
+    // To exit devices on on-screen navigation bar, you can hold your home button
+    // to open task manager / recent app menu, or use dedicated recent key on
+    // newer devices
+    @Override
+    public void onBackPressed() {
+        if(!usesSoftkey){
+            super.onBackPressed();
+        }
+    }
 }