Chain_of_Responsibility :线程"main“java.lang.NoClassDefFoundError中出现异常

Question

我的问题如下:我有一个java代码，写在一个.java文件中-- Chain_of_Responsibility，代码在我的问题的最后。我在Linux上用

javac Chain_of_Responsibility.java

并将我所有的.class文件放在同一个目录中。然后我试着用我的程序运行

java Chain_of_Responsibility

并获取“线程中的异常"main”java.lang.NoClassDefFoundError: Chain_of_Responsibility“。我尝试使我的主函数成为静态函数，在不同的.java文件中编写我所有的类，但没有成功。所以我不知道该怎么做。你能帮帮我吗?

package COR;

public class Chain_of_Responsibility
{
public void main(String[] args)
{
    //Create the Chain of Responsibility

    Handler chain = build_chain();

    //Trying to handle the request (valid are cheese, meet or banana)

    chain.handle_request(args[1]);
}

private Handler build_chain()
{
    //Creating the chain

    Handler monkey = new Monkey();
    Handler wolve = new Wolve();
    Handler mouse = new Mouse();

    //First nide is Monkey, then Wolve and then Mouse

    monkey.set_next_handler(wolve);
    wolve.set_next_handler(mouse);

    //Returning the first node in the chain

    return monkey;
}
}

abstract class Handler
{
Handler next_handler;

public void set_next_handler(Handler next_handler)  
{
    //Setting next handler in the chain

    this.next_handler = next_handler;
}

public abstract void handle_request(String request);
}

class Mouse extends Handler
{
public void handle_request(String request)
{
    //Trying to handle the request

    if (request == "cheese")
    {
        //Succesful try

        System.out.println("Mouse handles cheese!");
    }
    else
    {
        //Cannot handle request

        System.out.println("Mouse in unable to handle cheese" +  request + "!");

        if (next_handler != null)
        {
            //Sending request to the next handler

            next_handler.handle_request(request);
        }
        else
        {
            //If there is no handlers left, alert about crash

            System.out.println("Chain ends without success!");
        }
    }
}
}

class Wolve extends Handler
{
public void handle_request(String request)
{
    //Trying to handle the request

    if (request == "meet")
    {
        //Succesful try

        System.out.println("Wolve handles meet!");
    }
    else
    {
        //Cannot handle request

        System.out.println("Wolve in unable to handle cheese" +  request + "!");

        if (next_handler != null)
        {
            //Sending request to the next handler

            next_handler.handle_request(request);
        }
        else
        {
            //If there is no handlers left, alert about crash

            System.out.println("Chain ends without success!");
        }
    }
}
}

class Monkey extends Handler
{
public void handle_request(String request)
{
    //Trying to handle the request

    if (request == "banana")
    {
        //Succesful try

        System.out.println("Monkey handles banana!");
    }
    else
    {
        //Cannot handle request

        System.out.println("Monkey in unable to handle" +  request + "!");

        if (next_handler != null)
        {
            //Sending request to the next handler

            next_handler.handle_request(request);
        }
        else
        {
            //If there is no handlers left, alert about crash

            System.out.println("Chain ends without success!");
        }
    }
}
}

Answer 1

尝试java COR.Chain_Of_Responsibility并使您的main方法成为static

编辑

您必须在项目的根目录下启动java...，例如，如果您的Chain_of_responsibiliy.java在/src/COR中，则启动/src

Answer 2

首先，确保您的目录结构与包结构相匹配。这意味着，由于您的类位于名为COR的包中，因此源文件应位于名为COR的目录中。

因此，假设您的项目在C:\MyProject中，您应该有一个名为C:\MyProject\COR的目录，其中包含源文件Chain_of_Responsibility.java。

然后从目录C:\MyProject编译并运行它

C:\MyProject> javac COR\Chain_of_Responsibility.java
C:\MyProject> java COR.Chain_of_Responsibility

注意：javac命令需要源文件的路径；java命令需要完全限定的类名(而不是类文件的路径)。

如果上面的方法不起作用，那么很可能设置了CLASSPATH环境变量。您可以通过使用-cp选项显式指定类路径来覆盖它：

C:\MyProject> java -cp . COR.Chain_of_Responsibility

(而且，您的main方法必须是static，正如其他人已经指出的那样)。