interface Animal {
String talk();
}
class Frog implements Animal {
public String talk() {
return "ggg!";
}
}
class Cat implements Animal {
public String talk() {
return "miao";
}
}
class Creature {
private Animal state = new Frog();
public void greet() {
System.out.println(state.talk());
}
public void toCat() {
state = new Cat();
}
}
public class MainClass {
public static void main(String args[]) {
Creature creature = new Creature();
creature.greet();
creature.toCat();
creature.greet();
}
}