8.1向上转型

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package sedion.nsg.upcasting;

 

public enum Note {

    MIDDLE_C,C_SHARP,B_FLAT;

}

　　

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package sedion.nsg.upcasting;

public class Instrument {

    public void play(Note n){

        Syso.print("Instrument.play()");

    }

}

　　

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package sedion.nsg.upcasting;

 

public class Wind extends Instrument{

    public void play(Note n){

        Syso.print("Wind.play()");

    }

}

　　

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package sedion.nsg.upcasting;

 

public class Music {

    public static void tune (Instrument i){

        i.play(Note.MIDDLE_C);

    }

    public static void main(String[] args) {

        Wind flute = new Wind();

        tune(flute);

    }

}