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

@@ -27,13 +27,47 @@ public class GasCar extends Car implements Refuelable {
         this.fuelType = fuelType;
     }
 
-    // TODO: Override getEnergyType() → return fuelType + " (Gas)"
 
-    // TODO: Implement refuel(double amount)
-    // Validate amount
-    // Cap at 100
+    @Override
+    public String getEnergyType() {
+        return (fuelType + " (Gas)");
+    }
 
-    // TODO: Override showDetails()
-    // Call super.showDetails()
-    // Print fuel level and fuel type
+
+    @Override
+    public void refuel(double amount) {
+        if(amount<0) {
+            System.out.println("amount cannot be negative");
+        }
+        else {
+            fuelLevel += amount;
+        }
+
+        if(fuelLevel>100) {
+            fuelLevel = 100;
+        }
+    }
+
+
+    @Override
+    public void showDetails() {
+        super.showDetails();
+        System.out.println(" | fuel level: " + fuelLevel +
+                           " | fuel type: " + fuelType
+        );
+    }
+
+    @Override
+    public boolean needsService(Vehicle v) {
+        if(v.getMileage()>12000)
+            return true;
+
+        return false;
+    }
+
+    @Override
+    public void performService() {
+        System.out.println("Engine oil changed");
+        this.fuelLevel = 100;
+    }
 }