main程序输出:
class Alpha {
Alpha get() {
return this;
}
void message() {
System.out.println("This is Alpha");
}
}
class Beta1 extends Alpha {
void message() {
System.out.println("This is Beta1");
}
}
class Beta2 extends Alpha {
Beta2 get() {
return this;
}
void message() {
System.out.println("This is Beta2");
}
}
public class Main {
public static void main(String[] args) {
new Beta1().get().message();
new Beta2().get().message();
}
} 
