implement the set and get of the Lautstaerke in the UsbPlayer class

src/main/java/device/UsbPlayer.java

@@ -2,6 +2,16 @@ package device;
 
 public class UsbPlayer implements Device{
 
+     private int Lautstaerke=0;
+
+    public void setLautstaerke(int ls){
+        if(Lautstaerke < 100) {
+        Lautstaerke += 1;
+    } else {
+        Lautstaerke = 100;
+    }		}
+    public int getLautstaerke(){return Lautstaerke;}
+
     @Override
     public void louder() {
 

src/test/java/device/UsbPlayerTest.java

@@ -6,6 +6,8 @@ import static org.junit.jupiter.api.Assertions.*;
 
 class UsbPlayerTest {
 
+    UsbPlayer up =new UsbPlayer();
+
 /*
     @Test
     void louder() {