Version 3 working

app/src/main/java/com/example/ueberwachungssystem/MainActivity.java

 import android.os.Bundle;
 import android.os.IBinder;
 import android.util.Log;
+import android.view.Menu;
+import android.view.MenuItem;
 import android.view.View;
 import android.widget.ImageView;
+import android.widget.Toast;
 import android.widget.ToggleButton;
 
 import com.example.ueberwachungssystem.Detection.Accelerometer;
                     }
                 }
             });
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+        }else{
+            Toast.makeText(getApplicationContext(),"Bitte Zugriffsrechte gewähren",Toast.LENGTH_SHORT).show();
+        }
+    }
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.options_menu, menu);
+        return true;
+    }
+    public boolean onOptionsItemSelected(MenuItem item) {
+        Toast.makeText(this, "Selected Item: " + item.getTitle(), Toast.LENGTH_SHORT).show();
+        PopUpClass popUpClass;
+        switch (item.getItemId()) {
+            case R.id.Rechteverwaltung:
+                popUpClass = new PopUpClass(MainActivity.this);
+                popUpClass.showPopupWindow(inputImageView);
+                popUpClass.RechtePrüfen();
+                return true;
+            case R.id.Sensoren:
+                popUpClass = new PopUpClass(MainActivity.this);
+                popUpClass.showPopupWindow(inputImageView);
+                popUpClass.Sensoren();
+                return true;
+            case R.id.Impressum:
+                popUpClass = new PopUpClass(MainActivity.this);
+                popUpClass.showPopupWindow(inputImageView);
+                popUpClass.Impressum();
+                return true;
+            default:
+                return super.onOptionsItemSelected(item);
         }
     }