productive for quieter() if volume is zero

src/main/java/device/radioPlayer/RadioPlayer.java

@@ -29,14 +29,14 @@ public class RadioPlayer implements Device {
 
     @Override
     public void louder() {
-        if(Lautstaerke < 100){
-        Lautstaerke+=1;}
+        if(Lautstaerke < 100){Lautstaerke+=1;}
         else Lautstaerke = 100;
     }
 
     @Override
     public void quieter() {
-        Lautstaerke-=1;
+        if(Lautstaerke > 0){Lautstaerke-=1;}
+        else Lautstaerke = 0;
     }
     @Override
     public int getVolume() {