无关紧要

src/chapter4/example14/Example14.java

@@ -1,2 +1,36 @@
-package chapter4.example14;public class Example14 {
+package chapter4.example14;
+
+abstract class Animal {
+    abstract void shout();
+}
+
+class Cat extends Animal {
+    public void shout() {
+        System.out.println("喵喵...");
+    }
+}
+
+class Dog extends Animal {
+    public void shout() {
+        System.out.println("汪汪...");
+    }
+}
+
+class Example14 {
+    public static void main(String[] args) {
+        Animal cat = new Cat();
+        Animal dog = new Dog();
+
+        cat.shout();
+        dog.shout();
+    }
+}
+
+class Example15 {
+    public static void main(String[] args) {
+        Dog dog = new Dog();
+        Animal an = dog;
+
+        an.shout();
+    }
 }