Add all living beings in the circus

src/main/java/Animal.java

@@ -0,0 +1,6 @@
+public class Animal {
+
+    public String speak() {
+        return null;
+    }
+}

src/main/java/Bird.java

@@ -0,0 +1,5 @@
+public class Bird extends Animal {
+    public void fly() {
+        System.out.println("Whee ...");
+    }
+}

src/main/java/Circus.java

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+public class Circus {
+    private static Animal[] animals = {
+            new Duck(),
+            new Parrot()
+    };
+    private static Equipment[] equipments = {
+            new Ladder(50),
+            new Cannon(5),
+            new Cannon(100)
+    };
+
+    private static void makeAnimalsTalk() {
+        for (Animal a : animals) {
+            System.out.println(a);
+            System.out.println(a.speak());
+        }
+    }
+
+    private static int calculateValue(Equipment[] equipments) {
+        int total = 0;
+        for (Equipment e : equipments) {
+            if (e.getValue() <= 5) {
+                System.out.println("Ignoring low value item: " + e.getValue());
+            } else {
+                total += e.getValue();
+                System.out.println("Adding item value: " + e.getValue());
+                // some
+                // more
+                // code
+                // here ...
+            }
+        }
+        return total;
+    }
+
+    public static void main(String[] args) {
+        makeAnimalsTalk();
+        System.out.println("Total value of equipments " + calculateValue(equipments));
+    }
+}

src/main/java/Duck.java

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+public class Duck extends Bird {
+    @Override
+    public String speak() {
+        return "Quack Quack";
+    }
+
+    @Override
+    public String toString() {
+        return "I'm a Duck";
+    }
+
+    public void swim() {
+        System.out.println("I'm swimming...");
+    }
+}

src/main/java/Parrot.java

@@ -0,0 +1,11 @@
+public class Parrot extends Bird {
+    @Override
+    public String speak() {
+        return "Polly wants a cracker";
+    }
+
+    @Override
+    public String toString() {
+        return "I'm a parrot";
+    }
+}