I recently moved from Eclipse to IntelliJ and I was really used to see any kind of warnings in the tree of my project in eclipse.
I think in IntelliJ by default compilation errors are displayed in the project tree or maybe it worked by enabling the "build project automatically" setting. But I did't find any way to enable the same for simple warnings (e.g. unused imports).
Does somebody know how I could achieve this or anything similar to it so I can simple get informed about any warnings?
I would be happy about any help I can get
Most inspections run in the background only for the currently open file for the performance reasons, therefore there is no way to mark the files with inspection warnings in the project view.
Use Analyze | Inspect Code to get the list of the files with warnings.
What are the possible causes of a "java.lang.Error: Unresolved compilation problem"?
Additional information:
I have seen this after copying a set of updated JAR files from a build on top of the existing JARs and restarting the application. The JARs are built using a Maven build process.
I would expect to see LinkageErrors or ClassNotFound errors if interfaces changed. The above error hints at some lower level problem.
A clean rebuild and redeployment fixed the problem. Could this error indicate a corrupted JAR?
(rewritten 2015-07-28)
Summary: Eclipse had compiled some or all of the classes, and its compiler is more tolerant of errors.
Long explanation:
The default behavior of Eclipse when compiling code with errors in it, is to generate byte code throwing the exception you see, allowing the program to be run. This is possible as Eclipse uses its own built-in compiler, instead of javac from the JDK which Apache Maven uses, and which fails the compilation completely for errors. If you use Eclipse on a Maven project which you are also working with using the command line mvn command, this may happen.
The cure is to fix the errors and recompile, before running again.
The setting is marked with a red box in this screendump:
try to clean the eclipse project
you just try to clean maven by command
mvn clean
and after that following command
mvn eclipse:clean eclipse:eclipse
and rebuild your project....
Your compiled classes may need to be recompiled from the source with the new jars.
Try running "mvn clean" and then rebuild
The major part is correctly answered by Thorbjørn Ravn Andersen.
This answer tries to shed light on the remaining question: how could the class file with errors end up in the jar?
Each build (Maven & javac or Eclipse) signals in its specific way when it hits a compile error, and will refuse to create a Jar file from it (or at least prominently alert you). The most likely cause for silently getting class files with errors into a jar is by concurrent operation of Maven and Eclipse.
If you have Eclipse open while running a mvn build, you should disable Project > Build Automatically until mvn completes.
EDIT:
Let's try to split the riddle into three parts:
(1) What is the meaning of "java.lang.Error: Unresolved compilation
problem"
This has been explained by Thorbjørn Ravn Andersen. There is no doubt that Eclipse found an error at compile time.
(2) How can an eclipse-compiled class file end up in jar file created
by maven (assuming maven is not configured to used ecj for
compilation)?
This could happen either by invoking Maven with no or incomplete cleaning. Or, an automatic Eclipse build could react to changes in the filesystem (done by Maven) and re-compile a class, before Maven proceeds to collect class files into the jar (this is what I meant by "concurrent operation" in my original answer).
(3) How come there is a compile error, but mvn clean succeeds?
Again several possibilities: (a) compilers don't agree whether or not the source code is legal, or (b) Eclipse compiles with broken settings like incomplete classpath, wrong Java compliance etc. Either way a sequence of refresh and clean build in Eclipse should surface the problem.
I had this error when I used a launch configuration that had an invalid classpath. In my case, I had a project that initially used Maven and thus a launch configuration had a Maven classpath element in it. I had later changed the project to use Gradle and removed the Maven classpath from the project's classpath, but the launch configuration still used it. I got this error trying to run it. Cleaning and rebuilding the project did not resolve this error. Instead, edit the launch configuration, remove the project classpath element, then add the project back to the User Entries in the classpath.
I got this error multiple times and struggled to work out. Finally, I removed the run configuration and re-added the default entries. It worked beautifully.
Just try to include package name in eclipse in case if you forgot it
Import all packages before using it, EX: import java.util.Scanner before using Scanner class.
These improvements might work and it will not give Java: Unresolved compilation problem anymore.
Also make sure to check compiler compliance level and selected jdk version is same
As a weird case, I encountered such an exception where the exception message (unresolved compilation bla bla) was hardcoded inside of generated class' itself. Decompiling the class revealed this.
I had the same issue using the visual studio Code. The root cause was backup java file was left in the same directory.
Removed the backup java file
When the build failed, selected the Fix it, it cleaned up the cache and restarted the workSpace.
IntelliJ IDEA suggests there is compile error in source code of jetty.
In Eclipse, it does suggest nothing. And i can run this code. So i think this is the problem of IDEA.
My questions is how to disable this??
You can't just disable compile errors of source file in intellij. You can just disable inspection of some code patterns or compile warnings.
You can flag the folder not to be a source folder in module configuration, and the file will not be compiled anymore...
(But probably you need to investigate the underlined error to fix it really... maybe there is a conflict or a missing library in project configuration like the defined java Project Language Level)
Similar to this question, I'd like to have a warning prompt before I am allowed to commit files into Subversion which contain compiler warnings.
Unlike the linked question, I'm using the standard Subversive team provider. Any suggestions? I don't see anything obvious in the preferences.
I've concluded there is no way to do this with Subversive and have raised an enhancement request about it:
Bug 263442 - Add a pre-commit check for files with errors and warnings
Today, I ran into a java source file that had a typo in the 'package' statement at the top. The name of the package did not match the name of the directory the file was sitting in (one extra 's' at the end).
To my surprise, javac from 1.6, checkstyle, and pmd all passed the file as OK. The only tool that got around to complaining was javadoc, and only because it was the only file in the package, and a package with no classes in it is a fatal error to javadoc.
Is there some option to javac, or some other command-line tool (preferably with a maven plugin maven) that will squeal about this sort of goof?
I tested this with the latest version of Eclipse and it complains. Eclipse has Maven support.
Well, this seems like an interesting "feature". I fight with such errors regularly once a year. I would guess that PMD, FindBugs or a tool like that will find these errors. However if you say they do not, I can think of only three other options at the moment:
Use Eclipse compiler from Maven (to compile the sources and see the error). This should be possible although I have never tried it so far.
Create a custom PMD rule that will check the Java package name and compare it with the directory name.
Create your own Maven plug-in that will check it. This may not be very easy if you have not develop a Maven plug-in so far.
These are just ideas and should be treated as such.