implement Vehicle Management System

src/main/java/org/model/GasCar.java

@@ -28,10 +28,57 @@ public class GasCar extends Car implements Refuelable {
     }
 
     // TODO: Override getEnergyType() → return fuelType + " (Gas)"
+    @Override
+    public String getEnergyType()
+    {
+        return fuelType+" (Gas)" ;
+    }
 
     // TODO: Implement refuel(double amount)
     // Validate amount
     // Cap at 100
+    public void refuel(double amount)
+    {
+        if (amount<0)
+        {
+            System.out.println("Error : the refuel amount can not be negative. :)");
+            return;
+        }
+        if (amount==0)
+        {
+            System.out.println("Nothing for refuel! :)");
+            return;
+        }
+        if (amount>0)
+        {
+            fuelLevel+=amount;
+            if(fuelLevel>100)
+            {
+                fuelLevel=100;
+                System.out.println("Tank is full :)");
+            }
+            else
+                System.out.println("fuel level : " + fuelLevel + "%");
+        }
+    }
 
     // TODO: Override showDetails()
+    @Override
+    public void showDetails() {}
+
+    @Override
+    public boolean needsService(Vehicle v)
+    {
+        if (this.getMileage() > 12000)
+            return true;
+        return false;
+    }
+
+    @Override
+    public void performService()
+    {
+        System.out.println("Engine oil changed");
+        fuelLevel = 100 ;
+        System.out.println("fuel level : 100%");
+    }
 }