- Java code
package polymorphism.music;public enum Note { MIDDLE_C, C_SHARP, B_FLAT; // Etc.}package polymorphism.music;class Instrument { public void play(Note n) { System.out.println("Instrument.play()"); }}package polymorphism.music;// Wind objects are instruments// because they have the same interface:public class Wind extends Instrument { // Redefine interface method: public void play(Note n) { System.out.println("Wind.play() " + n); }} package polymorphism.music;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); // Upcasting }}结果：
D:\my java>javac -d . Instrument.java Music.java Wind.java Note.java
D:\my java>java Music
Exception in thread "main" java.lang.NoClassDefFoundError: Music
Caused by: java.lang.ClassNotFoundException: Music
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: Music. Program will exit.
我不明白为什么编译通过 但运行不了呢 那点出错了呢
------解决方案--------------------
CLASS文件没有找到Music
你看一下MUSIC.class文件在不在
------解决方案--------------------
路径不对......
如下:
D:\my java\polymorphism\music>javac -d . Instrument.java Music.java Wind.java No
te.java
D:\my java\polymorphism\music>java polymorphism.music.Music