Switch raises NoClassDefFoundError in tomcat using undefined inner classes

Question

I have a very simple listing

my.package.data.util

public enum Mode { SQLEXPORT, PREVIEW, PRINT } 

What is used in another class, since enumerations should be used

my.package.program.ComponentController

 switch (_mode) { // line 278, _mode is of type my.package.data.util.Mode case PREVIEW: // Do thing for preview break; case SQLEXPORT: // Do thing for SQL break; case PRINT: // Do thing for print break; default: throw new IllegalArgumentException(); } 

These two classes are in the same project and compiled into a jar file.

Then the web project uses this library (placed in the WEB-INF/lib folder). But, when the time comes to use this library and, in particular, this switch, NoClassDefFoundError appears:

NoClassDefFoundError: my / package / program / ComponentController $ 1

in my.package.program.ComponentController.doCall (ComponentController.java:278)

This is something that I cannot understand at several levels:

• Why is Java trying to load the inner class (as seen at $1 ). There is no inner class in the ComponentController , and it has never been.
• Why does Java think the switch uses this inner class as an argument
• If the class my.package.data.util.Mode disappeared.

What's going on here?

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Additional information is not in the original question

• ComponentController extends another class, SessionBuilder . This class also has no inner classes.

I decompiled ComponentController using javap and tried to find interesting things in the resulting byte code.

It looks like there really is an inner class in the byte code:

 public class my.package.program.ComponentController extends my.other.package.SessionBuilder SourceFile: "ComponentController.java" InnerClasses: static #192 of #2; //class my/package/program/ComponentController$1 of class my/package/program/ComponentController 

This class is used whenever my.package.data.util.Mode referenced:

 #192 = Class #486 // my/package/program/ComponentController$1 #193 = Utf8 #194 = Utf8 InnerClasses #195 = Utf8 _mode #196 = Utf8 Lmy/package/data/util/Mode; 

And also, when the transition actually occurs:

 183: getstatic #102 // Field my/package/program/ComponentController$1.$SwitchMap$my$package$data$util$Mode:[I 186: aload_0 187: getfield #5 // Field _mode:Lmy/package/data/util/Mode; 190: invokevirtual #103 // Method my/package/data/util/Mode.ordinal:()I 193: iaload 194: tableswitch { // 1 to 3 1: 220 2: 335 3: 440 default: 516 } 

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Further research on issues related to Rich caused something interesting: the jar built from the library project differs by the local installation of tomcat and the one used to create the jar for the production server:

Left: jar in WEB-INF/lib via local tomcat using eclipse, right: jar , like ANT built

Now it seems that the build process used by eclipse when publishing to the local tomcat is different from what ANT does (this is AFAIK just a simple javac call)

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Ok, now I just copied the jar created by ANT to the local WEB-INF/lib cats, and everything works fine. Of course, this means that after every change in the library project, I have to manually copy the new jar to my tomcat lib.

I filed this as an error report in eclipse and report any news.

Answer 1

In accordance with this question:

... Sun Javac 1.6 creates an extra synthetic class every time you use the Enum switch.

And in accordance with this question you are not alone.

Answer 2

In my experience, the problem is that this new class is not deployed by Eclipse, but it is generated during the build process.