尝试从命令行运行时NoClassDefFoundError

Question

Apologies in advance - I know there are many, many, many very similar questions but I wanted to ask something specific to my situation.

I have a bunch of java and jar files in the same directory. I am able to compile fine and thus end up with a number of class files in the same dir. But when I go to execute the program it gives a NoClassDefFoundError saying it can't find the specified class:

C:\Users\DB\Desktop\nextreports-integration-demo\src\ro\nextreports\integration>
java -cp ".;*.jar" SimpleDemo
Exception in thread "main" java.lang.NoClassDefFoundError: SimpleDemo (wrong nam
e: ro/nextreports/integration/SimpleDemo)

I tried the same thing from a higher-level dir but it made no difference:

C:\Users\DB\Desktop\nextreports-integration-demo\src>java -cp ".\ro\nextreports\
integration\*.jar;.\ro\nextreports\integration" SimpleDemo
Exception in thread "main" java.lang.NoClassDefFoundError: SimpleDemo (wrong nam
e: ro/nextreports/integration/SimpleDemo)

The package statement in the source file is:

package ro.nextreports.integration;

I have a feeling I'm overlooking something very elementary. Thanks in advance.

Edit: Thanks very much. It works with the following:

java -cp ".\ro\nextreports\integration\nextreports-engine-6.3.jar;.\ro\nextreports\integration\commons-jexl-2.1.1.jar;.\ro\nextreports\integration\commons-logging-1.1.1.jar;.\ro\nextreports\integration\derby-10.10.1.1.jar;.\ro\nextreports\integration\itext-2.1.7.jar;.\ro\nextreports\integration\itext-rtf-2.1.7.jar;.\ro\nextreports\integration\itextpdf-5.0.6.jar;.\ro\nextreports\integration\jcalendar-1.3.2.jar;.\ro\nextreports\integration\jcommon-1.0.15.jar;.\ro\nextreports\integration\jfreechart-1.0.12.jar;.\ro\nextreports\integration\jofc2-1.0.1.jar;.\ro\nextreports\integration\mysql-connector-java-5.1.23-bin.jar;.\ro\nextreports\integration\mysql-connector-java-5.1.23-bin.jar;.\ro\nextreports\integration\poi-3.7.jar;.\ro\nextreports\integration\winstone-lite-0.9.10.jar;.\ro\nextreports\integration\xstream-1.3.1.jar;" ro.nextreports.integration.SimpleDemo

But why can I not use wildcards for the *.jar files? For instance, the following leads to a NoClassDefFoundError for a class in any jar file I don't make explicit:

java -cp ".;.\ro\nextreports\integration\*.jar" ro.nextreports.integration.
SimpleDemo

Answer 1

Suppose this is your directory tree:

src/
   ro/
     nextreports/
       integration/
         SimpleDemo.class

From your package declaration, your compiled class should be in the integration subdiretory. Check that there really is a SimpleDemo.class in that directory. If that is correct, its classpath includes the contents of the src directory.

That means that, if you didn't have any JAR dependencies, you could run your application from the src directory like this:

java -cp . ro.nextreports.integration.SimpleDemo

You need to use the fully qualified class name.

Since you do have jars, you have to include them in the classpath as well. Suppose you have one JAR in the directory above src, and another in the current directory, you could use:

java -cp ../one.jar;another.jar;. ro.nextreports.integration.SimpleDemo

If you run it from another directory, it will still work if you review the classpath's relative directories or use absolute directories to describe your classpath. I am not sure but usually the current directory is always included in the classpath by the java executable.