摘要：
package sedion.nsg.upcasting;public enum Note { MIDDLE_C,C_SHARP,B_FLAT;} package sedion.nsg.upcasting;public class Instrument { public void play(Note n){ Syso.print("Instrument.play()"); }} package sedion.nsg.upcasting;public class Wind extends Instrument{ public void play(Note n){ Syso.p 阅读全文
