Command Line Error

[Differintegral]

I was going through the Java Core Vol I and there is a small class they have you compile from the command line. When using the javac Welcom.java everything goes fine. Once I try the java Welcome.class I receive an error. This is the class followed by the error message. The whole thing compiles perfectly fine in eclipse. What would cause it to error out on the command line? :eek:

public class Welcome
{
public static void main(String[] args)
{
String[] greeting = new String[3];
greeting[0] = "Welcome to Core Java";
greeting[1] = "by Cay Horstmann";
greeting[2] = "and Gary Cornell";

for (int i = 0; i < greeting.length; i++)
System.out.println(greeting[i]);
}
}


C:\CoreJaveBook\v1ch02\Welcome>java Welcome.class
Exception in thread "main" java.lang.NoClassDefFoundError: Welcome/class
Caused by: java.lang.ClassNotFoundException: Welcome.class
at java.net.URLClassLoader$1.run(URLClassLoader.java: 202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 07)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 48)
Could not find the main class: Welcome.class. Program will exit.

Any help would be great! Thank you!

[PhHein]

Welcome.class is not on the classpath, the jre doesn't know where to look for it.
That's why you should not use eclipse until you've mastered path, classpath and packaging mechanisms.
Read here: http://download.oracle.com/javase/tu...ems/index.html

[Differintegral]

Yeah it was just user error after a long night. Thanks!

[JosAH]

C:\CoreJaveBook\v1ch02\Welcome>java Welcome.class
Exception in thread "main" java.lang.NoClassDefFoundError: Welcome/class

javac compiles files but java runs classes; the name of the class is 'Welcome' and the file it is stored in is 'Welcome.class'; See how java had changed it to Welcome/class, assuming that Welcome is a package name; you should give java a class name (without the .class extension]

java Welcome

But PhHein is right: first you should study packages and classes and the path and classpath variables.

kind regards,

Jos

[Differintegral]

Thanks a lot for the information and help. I wasnt really paying attention. I already had the path and classpath set up. I just needed to pay attention to what I was typing. Thanks again!!!

[Differintegral]

Well I thought the classpath was set but it was not. The path was set of course or I would have never gotten the error message. The thing is the java Welcome works without the classpath set. How come?

[PhHein]

Wow, lack of coffee. I didn't notice the .class

Thanks Jos!

[JosAH]

Well I thought the classpath was set but it was not. The path was set of course or I would have never gotten the error message. The thing is the java Welcome works without the classpath set. How come?

If I'm not mistaken on a MS Windows machine the current directory is assumed to be in the classpath; I never assume anything:

java -cp . Welcome

The classpath values can also explicitly be set on the command line following the -cp flag.

kind regards,

Jos

[Tolls]

Even the java command assumes the current directory is on the classpath unless '-cp' has been given, or '-jar', in which case it takes only the values in the supplied classpath (either after -cp, or in the manifest for a jar).