Use machines to print working progress messages

src/main/java/core/basesyntax/MainApp.java

@@ -1,5 +1,14 @@
 package core.basesyntax;
 
 public class MainApp {
-
+    public static void main(String[] args) {
+        Machine truck = new Truck();
+        Machine bulldozer = new Bulldozer();
+        Machine excavator = new Excavator();
+        Machine[] machines = new Machine[]{truck, bulldozer, excavator};
+        for (Machine machine : machines) {
+            machine.doWork();
+            machine.stopWork();
+        }
+    }
 }