Java反射，类对象 [英] Java Reflection, Class Objects

问题描述

我的目标是读入命令行中我希望观察信息的类的名称。当我在运行时知道类名，我没有问题。我不能管理的是如何创建一个类对象基于字符串输入。

My objective is to read in to the command line the name of a Class I wish to observe info on. When I know the class name before runtime, I have no issue. What I can't seem to manage is how to create a class object based on a string input.

public class Tester {

    static void methodInfo2(Object obj) throws ClassNotFoundException {
        //some stuff        
        System.out.print("Test!");

    }

    public static void main (String args[]) throws ClassNotFoundException{
        String className = args[0];
        System.out.println("Class:  "+className);

        //myclass2 mc = new myclass2();
        //Class c = mc.getClass();
        Class argClass = Class.forName(className);

        try {
            methodInfo2(argClass);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }


    }

}

b $ b

在main方法中注释掉的行显示了我在过去做什么，当我在编译之前知道类名。以下取消注释的行显示了我认为应该工作，但我收到一个ClassNotFoundException。该类肯定存在，所以我不知道我有什么问题。

The 2 commented out lines in the main method show what I have done in the past when I know the class name before I compile. The following uncommented line shows what I thought should work, but I receive a ClassNotFoundException. The class certainly exists so I'm not sure what problem I'm having.

推荐答案

两个建议：

1. 确保你给它的完全限定名（例如java.lang.Thread，而不只是Thread）。


2. 确保编译的类文件实际位于类路径中。

1. Make sure you're giving it the fully-qualified name (e.g. "java.lang.Thread" and not just "Thread").
2. Make sure the compiled class file is actually on the classpath.

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