[Java 소스] 안전한 하향 캐스팅 예 Drummer.java Musician.java Pianist.java Program.java //기반 클래스public abstract class Musician { public abstract void Play(); } //파생 클래스 Drummerpublic class Drummer extends Musician { @Override public void Play() { System.out.println("두두둥"); } } //파생 클래스 Pianistpublic class Pianist extends Musician { @Override public void Play() { System.out.println("딩동댕"); } public void Tunn..