Develop Reference

'Source code does not match the bytecode' use IDEA debug JdbcTemplate

When I debug the JdbcTemplate sourcecode use IDEA，the IDE tips me：'Source code does not match the bytecode'
Screenshot:
and i use mvn to manage my project；my maven pom config is:
<dependency>
<groupId>org.springframework</groupId>
<artifactId>org.springframework.orm</artifactId>
<version>3.0.5.RELEASE</version>
</dependency>

This can also happen if you have multiple dependencies that themselves have different versions of the same dependency. This post on the JetBrains site shows how to enable the alternate source switcher in preferences.
https://intellij-support.jetbrains.com/hc/en-us/community/posts/206822215-what-does-Choose-Sources-do-and-how-can-I-undo-what-it-does-

Intellij gives a such warning when compiled code doesn't match the source code, i.e. you try to debug the code but it has changed and not rebuilt.
Make sure after you imported your code you didn't modify it. If you modify then first build/compile it before starting the debugger.
For example below code will cause this warning :-
public class HelloSO {
public static void main(String[] args) {
System.out.println("First time source code");
}
}
Now you compiled above class and start debugging it, everything works fine.
But after that you add one more print statement and try to put the debug point on that line without re-compile it, then in this case as byte code for new line is not generated, hence you will get same warning from IntelliJ.

After viewing the other similar questions and answers on this problem, none of which helped me. What solved the problem was simply adding a dependency. In my case I ran into this issue when I was attempting to debug org.springframework.web.servlet.DispatcherServlet. I finally noticed that IntelliJ could not find javax.servlet in my imports.
In my Maven project, I added
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>8.0.1</version>
</dependency>
to my pom.xml which solved the problem.
Double check that all of your imports are being resolved.

You can try this
Open or move to 'Project Panel'
Scroll down and find your library
Left click on your library
Inside the context menu, select 'Open Library Settings'
Once there, check that the binaries and sources are associated:

For me this issue was arising because I'd made changes to my source code but had not yet deployed them to the target device. It still allowed me to set up the debugging which was confusing, but then gave me this error.
To fix:
Rebuild your project / module
Redeploy to your target device
Run the debugger
After rebuilding / redeploying, your debug and deployed code will match up and you shouldn't get any more errors! Just a matter of matching up the two binaries.

I had the same issue, too. The root reason is two different jar packages have some conflicts. So I solved it by removing one of the conflicting jar package.

I had a problem like yours today. I found that my IntelliJ was set to work with Java version 16 and my project was built in Java version 11.
To fix it, I did this: clicked on File -> Project Structure -> Project Settings -> Project, and changed "Project SDK" property to version 11.
After clicking on OK button, I didn't get the message "source code does not match bytecode" anymore.

'No JUnit tests found' in Eclipse

So I'm new to JUnit, and we have to use it for a homework assignment. Our professor gave us a project that has one test class, BallTest.java. When I right click > Run as > JUnit Test, I get a popup error that says 'No JUnit tests found'. I know the question has been answered here(No tests found with test runner 'JUnit 4'), but closing eclipse, restarting, cleaning, and building doesn't seem to work. Below are screenshots of my run configuration, build path, and the class I'm trying to test.
BallTest.java
import static org.junit.Assert.*;
import junit.framework.Assert;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.JUnitCore;
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;
public class BallTest {
Ball ball;
/**
* #throws java.lang.Exception
*/
#Before
public void setUp() throws Exception {
System.out.println("Setting up ...");
Point2D p = new Point2D(0,0);
ball = new Ball(p);
}
/**
* #throws java.lang.Exception
*/
#After
public void tearDown() throws Exception {
System.out.println("Tearing down ...");
ball = null;
}
/**
* Test method for {#link Ball#getCoordinates()}.
*/
#Test
public void testGetCoordinates() {
assertNotNull(ball); // don't need Assert. because of the import statement above.
Assert.assertEquals(ball.getCoordinates().getX(), 0);
Assert.assertEquals(ball.getCoordinates().getY(), 0);
}
/**
* Test method for {#link Ball#setCoordinates(Point2D)}.
*/
#Test
public void testSetCoordinates() {
Assert.assertNotNull(ball);
Point2D p = new Point2D(99,99);
ball.setCoordinates(p);
Assert.assertEquals(ball.getCoordinates().getX(), 99);
Assert.assertEquals(ball.getCoordinates().getY(), 99);
}
/**
* Test method for {#link Ball#Ball(Point2D)}.
*/
#Test
public void testBall() {
Point2D p = new Point2D(49,30);
ball = new Ball(p);
Assert.assertNotNull(ball);
Assert.assertEquals(ball.getCoordinates().getX(), 49);
Assert.assertEquals(ball.getCoordinates().getY(), 30);
//fail("Not yet implemented");
}
public static void main (String[] args) {
Result result = JUnitCore.runClasses(BallTest.class);
for (Failure failure : result.getFailures()) {
System.out.println(failure.toString());
}
System.out.println(result.wasSuccessful());
}
}

Right Click on Project > Properties > Java Build Path > Add the Test folder as source folder.
All source folders including Test Classes need to be in Eclipse Java Build Path. So that the sources such as main and test classes can be compiled into the build directory (Eclipse default folder is bin).

If none of the other answers work for you, here's what worked for me.
Restart eclipse
I had source folder configured correctly, and unit tests correctly annotated but was still getting "No JUnit tests found", for one project. After a restart it worked. I was using STS 3.6.2 based of eclipse Luna 4.4.1

right click -> build path -> remove from build path
and then again add it ->
Right click on the folder named 'Test' > Build Path > Use as Source Folder.

I had the same problem and solved like this:
I deleted #Test annotation and retyped it.
It just worked, I have no idea why.

It looks like you're missing the runner definition on your test class, that could be the cause:
import org.junit.runners.JUnit4;
#RunWith(JUnit4.class)
public class BallTest {
...
}

Right click your project ->Properties->Java Build Path and go to Source Tab then add your test src folder.
Select Project menu and unselect 'Build Automatically' option if selected
Select Clean and then select 'Build Automatically' option
Restart Eclipse and run your junit.

junit4 require that test classname should be use Test as suffix.

Any solution didn't work for me until I change the name of the my test method. When name of test method starts with "test" is OK.
I am new in android programing and it was for me big surprise.

I think you have created your test classes outside the src folder. You can solve above problem by two way:
Add your package name in java build path->source
Move your package/class in src folder
I have the same problem and solved in this way both solutions working fine.

Try this
Right Click on the Unit Test Class,
Select "Run As" -> Run Configuration
In the "Test" tab, make sure in the field "Test runner" select drop down "JUnit 4"
Click "Apply"
Now Run the test!

I solved the problem by configuring the build path.
Right click on the project(or any of the subfolders)-> Build path -> Configure build path. Once the property window opens up, click on the 'Source' tab and add your src and tst folders.
But this alone did not work for me.
Strangely, I had to retype the annotations.(Project->clean or restart might also have worked though).

Came across this problem while upgrading projects across eclipse versions. For e.g. junits running well in Mars2.0 did not run on Neon. The following worked for me.
Delete .settings folder. Import project into eclipse.
Remove source folders. Then again use the folders as source folders. e.g - remove src/main/java from build path as source folder. -> Ok -> Again make this folder as source folder. Repeat it for main/resources, test/java, test/resources

In Eclipse Photon you may need to add JUnit 4 or 5 to the build path. Right click #Test and select 'Add JUnit 4 to build path'.

Click 'Run'->choose your JUnit->in 'Test Runner' select the JUnit version you want to run with.

The run configuration for a test class can create another cause (and solution) for this problem.
If you go to Run (or Debug) Configurations (using cmd-3 or clicking on the small dropdown buttons in the toolbar) you can see a configuration created for every test class you've worked with. I found that one of my classes that wouldn't launch had a run configuration where the Test Method field had somehow gotten inadvertently populated. I had to clear that to get it to work. When cleared it shows (all methods) in light text.
I'll add that strangely — maybe there was something else going on — it also seemed not to work for me until I fixed the "Name" field as well so that it included only the class name like the other JUnit run configurations.

I was using #RunWith(Parameterized.class) but missed to add the #Parameters annotation in the public static parameters method. After adding the annotation it worked.

The best way to resolve this issue is to put public Access modifier for your Junit Test Case class name and then run the scenario by right click on your Junit test case class and run as Junit Test.

The solution was, after making a backup of the src/test folder, removing it from the filesystem, then creating it again.
That's after I did the "Remove from build path" hint and it screwed the folders when opening the project in STS 4.

I had this problem too with JUnit 5.4.2. I use Eclipse 2019-09 with gradle 5.3.1.
So I had to add this two dependencies to build.gradle file with right configuration for it (testImplementation and testRuntimeOnly):
apply plugin: "java"
//enabled the Gradle’s native JUnit 5 support
test {
useJUnitPlatform()
}
testImplementation group: "org.junit.jupiter", name: "junit-jupiter-api", version: "${junitVer}"
testRuntimeOnly group: 'org.junit.jupiter', name: 'junit-jupiter-engine', version: "${junitVer}"

Some time if lots if Test files are there then Eclipse failed to pass -classpath options for all libs and path due to classpath param lenght limitations.
To Solve it go to Run
Configerations -> JUnit -> Your Project Config -> ClassPath -> Check "Use Temporary Jar Options"
At least it solved my problem.

Right Click on Project > Properties > Java Build Path > Libraries >
select classpath -> add Library -> Junit -> select junit version -> finish -> applay

Sometimes, it occurs when you add Junit Library in Module path. So, Delete it there and add in Class path.

Imported project in a new eclipse workspace, this resolved my issue.

Eclipse error ... cannot be resolved to a type

I have a dynamic web project that I am working on to migrate a jsp/servlet app from JRun to Tomcat.
I am getting the error: com.ibm.ivj.eab.dab.DatastoreJDBC cannot be resolved to a type.
I have the *.class files sitting inside a com/ibm/ivj/eab/dab folder (exactly how I found them). I have tried creating a jar file and adding that to the build path via "Add External Jar", I have also tried adding an "External Class Folder" and pointing to the folder that contains the "com" directory in question.
Still, the error persists. What is strange is if I start typing the package name eclipse actually auto-completes the class for me! (pictured below). Any ideas would be greatly appreciated. Maybe the classes were compiled for a much older java version and that is causing trouble? Maybe there is something I need to do to ensure the classes end up in the WEB-INF/lib directory?
I

Also If you are using mavenised project then try to update your project by clicking Alt+F5.
Or right click on the application and go to maven /update project.
It builds all your components and resolves if any import error is there.

Right click your project name.
Click Properties.
Click Java Build Path.
Click on Add Class Folder.
Then choose your class.
Alternatively, Add Jars should work although you claim that you attempted that.
Also, "have you tried turning it off and back on again"? (Restart Eclipse).

To solve the error "...cannot be resolved to a type.." do the followings:
Right click on the class and select "Build Path-->Exclude"
Again right click on the class and select "Build Path-->Include"
It works for me.

There are two ways to solve the issue "cannot be resolved to a type
":
For non maven project, add jars manually in a folder and add it in java build path. This would solve the compilation errors.
For maven project, right click on the project and go to maven -> update project. Select all the projects where you are getting compilation errors and also check "Force update of snapshots/releases". This will update the project and fix the compilation errors.

Project -> Clean
can at least sometimes be sufficient to resolve the matter.

For maven users:
Right click on the project
Maven
Update Project

Easy Solution:
Go to
Project property -> java builder path -> maven -> find c3p0-0.9.5.2.jar
and see the location where the file is stored in the local repository and go to this location and delete the repository manually.

Right click Project > Properties
Java Build Path > Add Class Folder
Select the bin folder
Click ok
Switch Order and Export tab
Select the newly added bin path move UP
Click Apply button

Solved the problem by dropping the jar into WEB_INF/lib.

copying the jar files will resolve. If by any chance you are copying the code from any tutorials, make sure the class names are spelled in correct case...for example i copied a code from one of the tutorials which had solr in S cap. Eclipse was continiously throwing the error and i also did a bit of googling ...everything was ok and it took 30 mins for me to realise the cap small issue. Am sure this will help someone

For many new users don't forget to add an asterisk (*) after your import statements if you wanna use all the classes in a package....for example
import java.io.*;
public class Learning
{
public static void main(String[] args)
{
BufferedInputStream sd = new BufferedInputStream(System.in);
// no error
}
}
================================================================
import java.io;
public class Learning
{
public static void main(String[] args)
{
BufferedInputStream sd = new BufferedInputStream(System.in);
// BufferedInputStream cannot be resolved to a type error
}
}

Solution :
1.Project -> Build Path -> Configure Build Path
2.Select Java Build path on the left menu, and select "Source"
3.Under Project select Include(All) and click OK
Cause :
The issue might because u might have deleted the CLASS files or dependencies on the project

Project -> Build Path -> Configure Build Path
Select Java Build path on the left menu, and select "Source"
click on Excluded and then Include(All) and then click OK
Cause : The issue might because u might have deleted the CLASS files
or dependencies on the project
For maven users:
Right click on the project
Maven
Update Project

First you need to update the pom.xml by adding below
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>4.1.6.RELEASE</version>
</dependency>
1] Right click your project name.
2] Click Properties.
3] Click Java Build Path.
4] Check on 'Maven Dependencies' in Order and Export tabl.
In my case, previously it was not enabled. So when I enabled it my #GetMapping annotation works fine..

Also, there is the solution for IvyDE users. Right click on project -> Ivy -> resolve
It's necessary to set ivy.mirror property in build.properties

I just closed all the files and reopened them, and voila!!! Hope this helps someone in the future ;)

Download servlet-api.jar file and paste it in WEB-INF folder it will work

Error: Could not find or load main class in intelliJ IDE

I'm a beginner in Java and am trying to run my code using IntelliJ that I just installed as my IDE with JDK 1.7. The following piece of code keeps does not even compile and keeps giving me the error:
Error: Could not find or load main class libTest
Code
import java.lang.Integer;
import java.lang.String;
import java.lang.System;
import java.util.*;
class book {
private String name = "trial";
private int bookCode=1;
private int issued=0;
public void Issue(){
if(issued==0) {
issued=1;
System.out.println("You have succesfully issued the book");
}
else {
System.out.println("The book is already issued. Please contact the librarian for further details");
}
}
public int checkCode() {
return bookCode;
}
String readName() {
return name;
}
public void setName(String newName){
name=newName;
}
public void setBookCode(int newCode){
bookCode=newCode;
}
}
class library {
private ArrayList books=new ArrayList();
public void getList(){
for(int bk:books){
String bName=books(bk).readName();
System.out.println((bk+1)+") "+bName);
}
}
}
public class libTest{
public static void main(String[] args){
library newLib= new library();
System.out.println("code working");
}
}
Is there any change that i have to make in the compiler settings?? Or is it the code.

This might help:
1) "Build" menu -> "Rebuild Project".
Sometimes Intellij doesn't rewrite the classes because they already exist, this way you ask Intellij to rewrite everything.
2) "Run" menu -> "Edit configuration" -> delete the profile -> add back the profile ("Application" if it's a Java application), choose your main class from the "Main Class" dropdown menu.
3)"Build" menu -> "Rebuild Project".

If none of the above answers worked for you, just close your IntelliJ IDE and remove the IntelliJ IDE file and folder from the root of your project:
rm -rf .idea *.iml
Then open the project with IntelliJ. It must work now.

For me the solution was to fix the output directory under project settings. Before I was using just "target" for the Project compiler output. Instead I updated it to have a full path e.g. D:\dev\sigplusjava2_68\target

I had this problem and I tried everything under the sun that I could think of and on this site.
None of my Java classes were being picked up after I pulled from a remote branch. All the classes had red Js by their names in the Project Hierarchy, not blue Cs.
In the end, I tried to follow this tutorial and a few steps in tried something not described and fixed the issue:
https://www.jetbrains.com/help/idea/creating-and-managing-modules.html
Here's what I did:
Goto File | Project Structure, or press Crtl+Shift+Alt+S
Select Modules under the Project Settings section.
In the Sources tab click Sources on the 'Mark as:' line.
Click the Apply button.
For some reason, all my classes then had blue C's.
Someone with a better understanding of how IntelliJ and/or IDE's might be able to explain the phenomenon, but all I know is now it can see all the classes and more importantly the main one, and run.

Invalidate cache and restart your IntelliJ, it worked for me.

Explicitly creating an out folder and then setting the output path to C:\Users\USERNAME\IdeaProjects\PROJECTNAME\out
seemed to work for me when just out, and expecting IntelliJ to make the folder wouldn't.
Also try having IntelliJ make you a new run configuration:
Find the previous one by clicking
then remove it
and hit okay.
Now, (IMPORTANT STEP) open the class containing your main method. This is probably easiest done by clicking on the class name in the left-hand side Project Pane.
Give 'er a Alt + Shift + F10 and you should get a
Now hit Enter!!
Tadah??
(Did it work?)

File > Project Structure > Modules > Mark "src" folder as sources.
This should fix the problem. Also check latest language is selected so that you don't have to change code or do any config changes.

I know this was asked a while ago, but I was just stumbling over this issue and thought my findings might help others. As pointed out, the error message is basically a result of the out folder. That's because, when you're trying to run the program, it compiles the code first, and puts the compiled result to the out location, and then it tries to load the compiled code from the out location. If the compiled code is not in the location expected, you'll get the error.
The point I'm particularly wanting to share is that some times, the code is not compiled (built), even though your run configuration specifies "Build" in the "Before launch" section of the configuration panel.
When can this happen?
One situation that can cause this to happen is if you're using modules and you manually delete the module out directory. For example, if I have a module named "foo", there should be a directory named foo under out/production. If you manually delete it, the build system may not know that it needs to be rebuilt.
Even worse, if you select Build | Build module 'foo', it still may not rebuild the module. If that's the case, you should select a file in the module, for example 'bar.java' and then select Build | Recompile 'bar.java'. Now the out directory out/production/foo should be restored.
Since IntelliJ typically knows about any changes going on, this surprised me, and took me a little time to figure out, so I thought I'd share.

Check your class module : I have encountered this problem with intellij :
I have a maven multi-module project, the problem is that i runing a class which not exist the module within the configuration, so my problem is fixed by setting the right module ("edit configuration" -> "use class of module")
may this help you

I had to mark the "src" folder as "Sources". After restarting IntelliJ and rebuilding the project I could run the project without further issues (see screenshot).
Edit: You can access the "Project Structure" tab via File->Project Structure or by pressing Ctrl+Shift+Alt+S.

I ran into this problem when my Java class was under src/main/kotlin. After I moved it to src/main/java, the problem was gone.

I have faced such problems when the class is in the default folder, i.e. when the class does not declare a package.
So I guess using a package statement (eg. package org.me.mypackage;) on top of the class should fix it.

Open Modules Tab (Press Ctrl+Shift+Alt+S). I had two modules under one project. I've solved the problem after removing the second redundant module (see screenshot).

After creating your project in intelliJ, try running the following command:
mvn package

I have tried all the hacks suggested here - to no avail. At the end I have simply created a new Maven application and manually copied into it - one by one - the pom.xml and the java files and resources. It all works now. I am new to IntelliJ and totally unimpressed but how easy it is to get it into an unstable state.

Invalidating cache didn't work.
I edited the main class java file with a dummy change and ran it. It worked.

In my case the problem seemed to be related to upgrading IntelliJ. When I did this I overwrote the files from the old IntelliJ with the files from the new IntelliJ (2017 community to 2018 community). After that all of my projects were broken. I tried everything in this thread and none of them worked. I tried upgrading gradle to the latest version (4 to 4.8) and that didn't work. The only thing that worked for me was deleting the entire IntelliJ folder and reinstalling it. All of my projects worked after that.

I have tried almost everything suggested in the answers here, but nothing worked for me.
After an hour of just trying to run my application, I noticed that my project's path included non-ASCII characters (Arabic characters). After I moved my project to a path with no non-ASCII characters, it executed just fine.

Goto File-> Invalidate Caches and Restart .
Else delete rm -rf .idea *.iml
and restart InteliJ

You can run the maven command on the pom.xml file in your project directory:
mvn clean install

For me - i tried few of the options above, did not work. Then i just renamed my Application class and that probably forced intelliJ to build a fresh jar and error message started to change. Then i renamed it back and it worked.

Mark the directory as a source directory. Opened via Ctrl+Shift+Alt+S

modules.xml with wrong content, I don't know what's matter with my IDEA.

I inherited a bunch of .JAVA files from elsewhere and couldn't figure out how to get them to work in any IDE. Ultimately I had to go to the command line where the Main.JAVA file was and run javac Main.java. This created a bunch of .CLASS files. The IDE's were then able to figure out what to do.

I got this error when using Scala/SBT. IntelliJ could not find the main class, even though everything was set up correctly.
My solution: delete the <user>/.sbt/<version>/plugins/target folder, then restart IntelliJ.

You probably would have specified a wrong package and the package hierarchy would not be right. Look below
The ide would highlight the wrong path in that case.

I'm using IntelliJ with Spring and my main class is wrapped in a JAR.
I had to mark the 'Include dependencies with "Provided" scope' in the Run/Debug configuration dialog

We are at File/Project Structure..
Answer might be:
Folder indicated as "content root" needs a child folder where the code is.
Plus find the button that marks code as excluded and not.
Not to be confused with tickbox that states excluded without telling in what phase and what**
Is it compiler exclude or runtime exclude? You are doomed to test and lot.
So no that tickbox but icons and colors.
As an idea we need to crack how it was originally thought to work. They never got it to work in first place and started add things in premature codaculation style.
It has been so many years and you cannot expect any improvement.
But as cure we can hack out some way to get it right every time.

Another thing you can check here is the actual command that is being passed to the JVM and make sure it looks OK. Scroll to the top of your Run console, it should be the first line.
Spaces in your Run Configuration VM Options field will malform the app startup command and can result in this error message
-DsomeArgument="arg with space must be quoted"

I am working with Kotlin but am guessing the problem is the same. I would start a project, create a single file and add main to it and the IDE couldn't find the main.
I tried the things in this list and none worked. I finally mentioned my frustration on one of the IntelliJ pages and was contacted. Of course, it worked fine for IntelliJ. After a couple of days back and forth, I noticed that the highlight function wasn't working and mentioned that. It turned out something was wrong with the IDE settings. I still don't know specifically what was wrong but the fix in my case was to reset the IDE settings. File->Manage IDE Settings->Restore Default settings.
After this, the green triangle start icon became visible to the left of my main function and things continued to work normally for subsequent projects.
Thanks to Konstantin at JetBrain's support for his patience.

JUnit4 + Eclipse "An internal error occurred during Launching"

I'm trying to run JUnit4 test cases on Eclipse 3.4.2 but it's not even starting for me. I have the junit-4.7.jar in my build path and the test application.
Here is a simple example that illustrates my problem
package test;
import org.junit.Before;
import org.junit.Test;
public class UTest {
#Test
public void test() {
}
#Before
public void setUp() throws Exception {
}
}
This compiles fine
Then I do "Run JUnit Test case" from Eclipse and I get an error dialog with this message
"Launching UTest' has encountered a problem
An internal error occurred during: "Launching UTest".
java.lang.NullPointerException
What causes these NullPointerExceptions? What am I doing wrong?

What worked for me after trying everything:
Go to help
Install New Software
Work with: Juno
Programming languages (expand it)
Install Java Development Tools
Restart
It works :)

I was able to fix this just by deleting the workspace and the Eclipse directory and starting over.

This worked for me:
create another copy of the test class (CopyOfUTest.java)
run the copy to make sure it passes
go into Run > Run Configurations
under JUnit, find the run configurations for the original class and the copied class
right click and delete the configuration of the original class
rename the configuration of the copied class to the original configuration name
delete the copied class from the project

None of the given answers here worked for me, so I ended up just installing and using InfiniTest instead. It doesn't have this problem, and it also runs the tests automatically so I can focus on my work.

Have you looked in the Eclipse error log? You can see it by opening the "Error Log" view.
http://help.eclipse.org/help32/topic/org.eclipse.pde.doc.user/guide/tools/views/error_log.htm

This error In eclipse can be caused if you are also using the Android Development Kit plugins:
"Launching UTest' has encountered a problem
An internal error occurred during: "Launching UTest".
java.lang.NullPointerException
Can be caused if you are loading a normal Java project into an Eclipse instance with android ADT plugins installed and enabled. In this situation, Eclipse looks for "Android" project files, and doesn't find any. So it says: "NullPointerException".
So to fix it, re-download Eclipse without the ADT Plugin: https://www.eclipse.org/downloads/
Then re-import your project fresh. And the junit tests run without a problem.
Many people hate eclipse for it's enigmatic error messages. It's like we are back in the 1950's punch card world, where there are no error messages. The program just halts and undefined behavior occurs.

Thanks that solved my problem too.
The problem started when i removed an old simulator, and created a new one.
Fix: Like the OP says remove the workspace, make sure to keep the projects inside it :)
then import them back to eclipse
"Sound like a lot of work" ?
Took me less than half a minute !!!

If you are using Android and its associated plugins, then Android only supports JUnit 3.
I resolved the problem by selecting Test Runner as JUnit 3.
In my class, JUnit 4 is added in the build path->libraries.
Then to run the test file, go to: Run As -> Run Configurations then select the corresponding test.java file and select Test Runner accordingly(whether it is JUnit 3 or 4).

Your code works fine for me.
Eclipse
Version: 3.4.1
Build id: M20080911-1700
I right click on the .java file RunAs JUnit Test. This would indicate the problem is caused by an Eclipse configuration problem, not a code problem.

I encountered a similar problem but I am using Python. This is what I did to solve/avoid it:
Removed my .project file and the project from Eclipse.
Created the project again.
Everything was working.
The problem seemed to be in the .project file where there were some references to CDT Builder and were not there in the new .project file.