java - 在java中使用字符串创建类对象时出错

Question

在创建使用 Class.forName() 的对象时，我收到以下错误。您能确认一下我哪里做错了吗？

Exception in thread "main" java.lang.ClassNotFoundException: ABC
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at RandomPrograms.ClassObjectFromString.main(ClassObjectFromString.java:32)

ClassObjectFromString.java

import java.lang.reflect.Constructor;

class ABC {
    ABC() {
        System.out.println("ABC called!!! ");
    }
    ABC(String a) {
        System.out.println("ABC called : " + a);
    }
}

class ClassObjectFromString {

    public static void main(String[] args) throws Exception {
        Class<?> clazz = Class.forName("ABC");
        Constructor<?> ctor = clazz.getConstructor(String.class);
        Object object = ctor.newInstance(new Object[] { "Message" });
    }
}

Answer 1

public static Class<?> forName(String className)

提供所需类的完全限定名称，其中也包括您的包名称。所以我们会RandomPrograms.ABC