JAVA 反射机制 运行后发生这样的错误提示是什么意思？

Question

public class test1 {public static void main(String[] args)throws Exception {Class<?> cls = Class.forName("demo6.Book");Book book = (Book)cls.newInstance();book.setTitle("JAVA");book.setPrice(32);System.out.println(book);}}Exception in thread "main" java.lang.InstantiationException: demo6.Bookat java.lang.Class.newInstance(Unknown Source)at demo6.test1.main(test1.java:8)Caused by: java.lang.NoSuchMethodException: demo6.Book.<init>()at java.lang.Class.getConstructor0(Unknown Source)... 2 more

Answer 1

检查Book类是否有无参构造

newInstance只支持无参构造
如果Book类有带参构造,没有无参构造就会报异常
如果不是这个原因,请把Book类代码贴出来