created classes Machine, Excavator, Truck, Bulldozer, added array of …

…Machines, created abstract methods doWork and stopWork

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 to 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 to work.");
+    }
+
+    @Override
+    public void stopWork() {
+        System.out.println("Excavator stopped working.");
+    }
+}

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

@@ -0,0 +1,7 @@
+package core.basesyntax;
+
+public abstract class Machine {
+    public abstract void doWork();
+
+    public abstract void stopWork();
+}

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

@@ -1,5 +1,16 @@
 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 = {truck, bulldozer, excavator};
+
+        for (int i = 0; i < machines.length; i++) {
+            machines[i].doWork();
+            machines[i].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 to work.");
+    }
+
+    @Override
+    public void stopWork() {
+        System.out.println("Truck stopped working.");
+    }
+}