Create new classes

src/main/java/core/basesyntax/Bulldozer.java

@@ -0,0 +1,13 @@
+package core.basesyntax;
+
+public class Bulldozer extends Machine{
+    @Override
+    public void doWork(){
+        System.out.println("Bulldozer started its work");
+    }
+
+    @Override
+    public void stopWork(){
+        System.out.println("Bulldozer stopped working");
+    }
+}

src/main/java/core/basesyntax/Excavator.java

@@ -0,0 +1,13 @@
+package core.basesyntax;
+
+public class Excavator extends Machine{
+    @Override
+    public void doWork(){
+        System.out.println("Excavator started its work");
+    }
+
+    @Override
+    public void stopWork(){
+        System.out.println("Excavator stopped working");
+    }
+}

src/main/java/core/basesyntax/Machine.java

@@ -0,0 +1,9 @@
+package core.basesyntax;
+
+public abstract class Machine {
+
+    public abstract void doWork();
+
+    public abstract void stopWork();
+
+}

src/main/java/core/basesyntax/Main.java

@@ -0,0 +1,11 @@
+package core.basesyntax;
+
+public class Main {
+    public static void main(String[] args){
+
+        MainApp mainApp = new MainApp();
+        mainApp.testing();
+    }
+}
+
+

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

@@ -2,4 +2,11 @@
 
 public class MainApp {
 
+    public void testing(){
+        Machine[] machines = {new Truck(), new Bulldozer(), new Excavator()};
+        for ( Machine mash : machines ) {
+            mash.doWork();
+            mash.stopWork();
+        }
+    }
 }

src/main/java/core/basesyntax/Truck.java

@@ -0,0 +1,13 @@
+package core.basesyntax;
+
+public class Truck extends Machine{
+    @Override
+    public void doWork(){
+        System.out.println("Truck started its work");
+    }
+
+    @Override
+    public void stopWork(){
+        System.out.println("Truck stopped working");
+    }
+}