Eclipse error: “The import XXX cannot be resolved”

问题

I\'m trying to work with Hibernate in Eclipse. I\'m creating a new simple project and I\'ve downloaded a collegue project too, via CVS. Both don\'t work, while on my collegue\'s Eclipse do. The problem is that, for each import of an Hibernate class, Eclipse says:

The import org.hibernate cannot be resolved

But all Hibernate jars are in the build path, that is:

antlr-2.7.6.jar
cglib-2.2.jar
commons-collections-3.1.jar
dom4j-1.6.1.jar
hibernate3.jar
hibernate-jpa-2.0-api-1.0.0.Final.jar
javassist-3.12.0.GA.jar
jta-1.1.jar
slf4j-api-1.6.1.jar

回答1:

Try cleaning your project by going to the following menu item:

Project > Clean...

If that doesn't work, try removing the jars from the build path and adding them again.

回答2:

Obviously there are cases where there is a valid issue however Eclipse throws this error for no good reason sometimes.

This still (2019-03) is an old (2010) Eclipse bug that can be resolved by making a negligible change to the project settings.

The setting I chose to change was: Project > Properties > Java Build Path > Order and Export > make a meaningless order change > Apply.

Changing the order back does not regress to the problem. Simply touching the file might also resolve the issue (I'll test touch next time).

回答3:

Clean the project. And double-check the jars being really on the build path (with no errors). Also make sure there is nothing in the "Problems" view.

回答4:

I found the problem. It was the hibernate3.jar. I don't know why it was not well extracted from the .zip, maybe corrupt. A good way to check if jars are corrupt or not is navigating through their tree structure in "Project Explorer" in Eclipse: if you can't expand a jar node probably it's corrupt. I've seen that having corrupt packages it's frequent when you drag and drop them to the "Project Explorer". Maybe it's better to move and copy them in the OS environment! Thankyou all.

回答5:

If is a Maven project, also click on Maven >> Update project... (F5)

回答6:

clean project Project - > clean...
Right click on project - >BuildPath - >Configure BuildPath - >Libraries tab - >

Double click on JRE SYSTEM LIBRARY - >Then select alternate JRE

回答7:

I solved it by removing the project (do not delete on the disk) and importing it again.

回答8:

I had the problem, that the classpath was broken somehow.

So right click on the project in Package explorer > Plug-in tools > Update classpath... did it for me

回答9:

Try adding JRE System Library in the build path of your project.

回答10:

I resolved this issue by updating the project: right click on the Maven project, select Maven -> Update Project -> select checkbox Force Updates of Snapshots/Releases.

回答11:

With me it helped changing the compiler compliance level. For unknown reasons it was set to 1.6 and I changed it to 1.8.

Once at project level right click on project > Properties > Java Compiler, while in Eclipse click on menu Window > Preferences > Java > Compiler.

回答12:

I tried all of the answers above but no luck. In my case, there is a generated build/classes folder with some additional ".class" files. I ended up going to the package explorer, right-clicking on the project and selecting the "Refresh" option and that made the build/classes folder available again resolving the issue.

回答13:

In my case it was a broken jar in the Maven repository. Delete jar files in repository and let Maven download them again.

When I ran mvn clean install from the command line, it ran fine, but Eclipse still could not compile the code. When I ran maven install in Eclipse then I saw that Maven complained about bad jar file. So I deleted it and ran maven install again. The problem was gone.

回答14:

In order to download non-existing jar file in your .m2 directory, you should run mvn clean install command for your project pom.xml. Then you should update the project dependencies by clicking Alt+F5. This works for me!

回答15:

Removing the "module-info.java" did resolve the issue for me!

This file was automatically generated and did appear in my hierarchy...

回答16:

I had the same problem because I added a jar I created, where I had set the packaging base directory other than the base directory of the classes. As a result the class e.g. java.util.List had to be imported as util.List although the suggested import was the first one.

Check the imported jars under referenced libraries to see that they are imported correctly

回答17:

I didn't understand the reasoning behind this but this solved the same problem I was facing. You may require these steps before executing steps mentioned in above solutions (Clean all projects and Build automatically).

right click project -> Properties -> Project Facets -> select Java -> Apply

回答18:

Whenever you come across this problem just go to Project > Clean, then select Clean all projects. It should get resolved, otherwise try to delete those jars and add them again. Last thing would be to try restarting Eclipse.

回答19:

This has solved my issue.

1) clean project Project -> clean...

2) Right click on project -> BuildPath -> Configure BuildPath -> Libraries tab -> Double click on JRE SYSTEM LIBRARY -> Then select alternate JRE

3) Click Save

4) Again go to your project in project explorer and right click to project -> BuildPath -> Configure BuildPath -> Libraries tab -> Double click on JRE SYSTEM LIBRARY -> This time select "Execution Environment"

5) Apply

回答20:

Please try and check whether all the libs are in place. I had the same issue. But I solved it by moving the lib folder and adding all the jars again in the build path.

回答21:

I got the same problem. I downloaded the jar and added it to the build path, but I didn't notice that the extension was .jar.zip. I again converted it to .jar and added to the build path.

It solved my problem. It's a very silly mistake but I wrote it here in case it could help someone.

回答22:

If you are working with Maven and have this problem, check the repository server (for example nexus server), if the artifact is there. Sometimes, they can change the name of the artifact and you try to get the artifact with its old name.

回答23:

Resolved by linking the source. From the explorer right click on the project, select properties, select Java Build Path, select Source from tabs, press button "LinkSource". And specifying the folder to add to the project.

回答24:

I couldn't import as well. Took me some hours to figure out, that I tried to use a 1.6 bound library/jar, while I was trying to compile for 1.8. When I switched my project also to use 1.6, the import issue has gone. All error messages were leading into wrong directions. Just in the source I found some limitations directing to 1.6 version. And: For example the .settings and .classpath (File-Search) -> org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.6 can give a hint, on such issues.

回答25:

I faced the same issue and I solved it by removing a jar which was added twice in two different dependencies on my pom.xml. Removing one of the dependency solved the issue.

回答26:

If it's a Maven project, go to pom.xml and remove all the dependency jars. Save it. Project will automatically build.

Then add dependency jars again (you can do Ctrl+Z). Save it. Project will automatically build and you won't see that error.

回答27:

For me, it seemed I was adding the wrong level of the library's folder. I downloaded the Jericho HTML Parser, unzipped it into eclipse-workspace/libraries/jericho-html-3.4/

Then when adding this as an external library folder, the trick was to navigate to that folder, highlight the "classes" folder and press Open. I had previously tried adding both the parent and various levels of subfolders and it didn't work.

This is pretty much explained here, it says

You can also add a class folder, a directory containing Java class files that are not in a JAR.

There are two lessons learnt here for me, apologies if these are off-topic:

Read the instructions carefully - as in word-by-word!
Do not give up - this it the first time I am adding a library, it took me around two hours to get it added.

回答28:

Solution for IDE eclipse

In my case I fixed it by correcting one of these two files that may be corrupt: .classpath or .project.

To repair any of the corrupted files, you can copy from another project that has both the .project file or .classpath file in question and is error-free. But be sure not to add additional settings that will not be used.

I hope it serves you