java command classpath issue

Question

I am having strange issue in this simple scenario.

I am having a jar file which contains following class:

package com.example;

public class Test{
    public void perform(){
       System.out.println("Performing testing one");
    }
}

And I have created a Main class to call the perform method as followed:

import com.example.Test;

public class Main{
    public static void main(String[] args) {
     Test test=new Test();
     test.perform();
    }
}

I have put both the jar and Main.java file in same folder and successfully compiled the Main.java file using following command:

javac -cp ".\*" Main.java

But when I am trying to run the Main class using following command:

java -cp ".\*" Main

It gives following error:

Error: Could not find or load main class Main

If I try to run Main class without -cp argument it gives following error:

Exception in thread "main" java.lang.NoClassDefFoundError: com/example/Test at Main.main(Main.java:5) Caused by: java.lang.ClassNotFoundException: com.example.Test 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) ... 1 more

The syntax is correct then what I am doing wrong here...?

didiz · Accepted Answer · 2017-04-22 06:50:00Z

0

When using -cp you need to specify jar names one by one. Using * does not usually add anything to the classpath. Good luck!

answered Apr 22, 2017 at 6:50

didiz

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2 Comments

Rohit Gupta Over a year ago

i have also tried to run java command as followed java -cp "test1.jar" Main but still same error

didiz Over a year ago

What about the jar where Test sits on, you appear to only have compiled main.java. Also, the jars need to be on local dir to be used this way, otherwise you need full path.

user207421 · Accepted Answer · 2017-05-02 06:21:20Z

0

Everything is wrong.

The source code should be in a directory called com/example.
You should be in the directory containing com.
The compiler command is
```
javac com/example/Main.java
```
The execute command is
```
java com.example.Main
```

You don't need a JAR file with only one class in it.

edited May 2, 2017 at 6:21

answered May 2, 2017 at 5:10

user207421

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Comments

Rohit Gupta · Accepted Answer · 2017-05-02 04:51:31Z

-2

After a lot of experiment and searches on net, I have finally found that we need to put ; after classpath to make it work. So following command does run the Main class:

java -cp ".\*"; Main

answered May 2, 2017 at 4:51

Rohit Gupta

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5 Comments

user207421 Over a year ago

That doesn't make it work, and it isn't necessary. It can't work unless you specify the class to run correctly, and you haven't.

Rohit Gupta Over a year ago

@EJP Can you please explain why java -cp ".\*"; Main works and java -cp ".\*" Main doesn't?

user207421 Over a year ago

Neither works. Cannot reproduce. You will get what I did: the same NoClassDefFoundError you mentioned in your post, unless you've changed your code.

Rohit Gupta Over a year ago

@EJP I have checked the posted code and the behavior does occur. I am using Java 1.8.0_73.

BSavaliya Over a year ago

@RohitGupta, Wow thanks buddy. i got my solution. i have tried to resolved for two days. you saved my time. thanks again

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