Develop Reference

Java and intelij idea [duplicate]

I just imported a project from subversion to IntelliJ IDEA 11 - it's a maven project. But I have a problem in maven library dependencies so that I can't include all maven dependencies automatically - IDEA shows dependency errors only when I open that class/ Thats what I get here:
So I want all dependencies to be added automatically - is that possible or do I have to go through all class files to identify and add maven dependencies?!
UPDATE: After doing some modifications I found how to resolve my problem in some way. Thats what I did:
but I think logically it will not include and check new dependencies ahead?!... Is there any settings area for this in intelliJ - auto export dependencies to classpath?

IntelliJ should download and add all your dependencies to the project's classpath automatically as long as your POM is compliant and all the dependencies are available.
When importing Maven projects into IntelliJ an information box usually comes up asking you if you want to configure Auto-Import for Maven projects. That means that if you make any changes to your POM those changes will be loaded automatically.
You can enable such feature going to File > Settings > Maven > Importing, there is a checkbox that says "Import Maven projects automatically".
If that doesn't help, then I would suggest to make a full clean-up and start again:
Close your project window (and IntelliJ) and remove all *.iml files and all .idea folders (there should be one per module)
Run mvn clean install from the command line
Re-import the project into IntelliJ and pay attention when it asks you to enable auto-import
IntelliJ 2016 Update:
The Import Maven Projects automatically setting has been moved to Build, Execution, Deployment > Build Tools > Maven > Importing in your IntelliJ preferences.

Fix before IntelliJ 14
File [menu] -> Settings -> maven -> importing and uncheck "use maven3 to import project"
ref: http://youtrack.jetbrains.com/issue/IDEA-98425 (which may have a few other ideas too)
Fix IntelliJ 15+
Ran into this again, with IntelliJ 15 this time, which has no "use maven3 to import" option available anymore. The cause was that sometimes IntelliJ "doesn't parse maven dependencies right" and if it can't parse one of them right, it gives up on all of them, apparently. You can tell if this is the case by opening the maven projects tool window (View menu -> Tool Windows -> Maven Projects). Then expand one of your maven projects and its dependencies. If the dependencies are all underlined in red, "Houston, we have a problem".
You can actually see the real failure by mousing over the project name itself.
In my instance it said "Problems: No versions available for XXX" or "Failed to read descriptor for artifact org.xy.z" ref: https://youtrack.jetbrains.com/issue/IDEA-128846
and
https://youtrack.jetbrains.com/issue/IDEA-152555
It seems in this case I was dealing with a jar that didn't have an associated pom file (in our maven nexus repo, and also my local repository). If this is also your problem, "urrent work around: if you do not actually need to use classes from that jar in your own code (for instance a transitive maven dependency only), you can actually get away with commenting it out from the pom (temporarily), maven project reload, and then uncomment it. Somehow after that point IntelliJ "remembers" its old working dependencies. Adding a maven transitive exclude temporarily might also do it, if you're running into it from transitive chain of dependencies."
Another thing that might help is to use a "newer version" of maven than the bundled 3.0.5.
In order to set it up to use this as the default, close all your intellij windows, then open preferences -> build, execution and deployment -> build tools -> maven, and change the maven home directory, it should say "For default project" at the top when you adjust this, though you can adjust it for a particular project as well, as long as you "re import" after adjusting it.
Clear Caches
Deleting your intellij cache folders (windows: HOMEPATH/.{IntellijIdea,IdeaC}XXX linux ~/.IdeaIC15) and/or uninstalling and reinstalling IntelliJ itself. This can also be done by going to File [menu] -> Invalidate Caches / Restart.... Click invalidate and restart. This will reindex your whole project and solve many hard-to-trace issues with IntelliJ.

When importing the project, select pom.xml instead of the project directory. It should work.

Try to Re-Import the project from the Maven Projects panel in IntelliJ IDEA. It should download and configure all the dependencies defined in your pom.xml automatically.
If download doesn't work from IDEA for some reason, try mvn install from the command line and see if the dependencies can be fetched.
Of course all the required dependencies and any custom repositories must be defined directly in the pom.xml file.

For IntelliJ 2016-2.4 (and I believe other new-ish versions):
View > Tool Windows > Maven Projects
In the newly revealed toolbar, select Maven settings (icon of a toolset).
When this screen opens, expand the Maven menu and click 'Importing'
Here, click "Import Maven projects automatically." Also ensure that the 'JDK for Importer' option matches the JDK version you mean to use.
Click OK. Now go to the red dependency in your pom.xml, select the red lightbulb, and click 'Update Maven indices'.

What helped me:
Navigage:
Settings | Build, Execution, Deployment | Maven
Specify "Maven home directory" - the place you installed the maven

If certain maven modules are not compiling check if their pom.xml is on the "ignored files" list. In IntelliJ goto
preferences -> project settings -> maven -> ignored files
and check if the related pom.xml is ignored.

I had the same issue and tried all the answers mentioned here, none worked.
The simple solution is go to your project folder and delete all the .idea and .iml files and restart the IntelliJ ide. It works. No need to do anything with the settings.

Open IntelliJ Idea, Go to
File > Other Settings > Default Settings... > Maven (Preferences) > Importing or|
Preferences > Maven > Importing
Click on Enable Auto-import in the console.

When you create a new project you simply need to choose the option:
...
Import project from external model
Create IDEA project structure over existing external model (Eclipse, Maven...)
...
You'll find it pretty straight forward from there.
And in your case you can close your project and simply create a new one. Choose your project's directory, which will override it, making it a Maven project.

Importing Maven dependencies may not work if you import the same path several times. This may happen automatically after importing an existing maven project. I can't figure out why this happens, so I'm inclined to think it is a bug.
For example, if my project is
hibernate
src/main
src/test
the three paths may be imported as top nodes:
hibernate
src/main
src/test
If such is the case, the dependencies appear to be right, but they won't be used until you remove the superfluous paths (in this case, src/main and src/test). Once you do this, refresh and click Build > Rebuild Project. IDEA will pick up the dependencies.
A symptom of this problem is that IDEA warns you of a duplicated path when you manually check a library (second screenshot in the question).
There are several ways to re-read the dependencies in case you need it. If you go to the “Maven Projects” tab, there is a “Reimport All Maven Projects” icon at the top left of the tab. If you suspect IDEA became confused you can click on File > Invalidate Caches.

First check path Specified for User Settings file: in Settings -> Build,Execution,Development -> Build Tools -> Maven .
The field should have path of the settings.xml of your maven. Also the settings.xml should have correct path of remote repository.

Go into your project structure, under project Settings, Modules, select the dependencies table. For each dependency, change the scope from 'Test' to 'Compile'.

If in the lower right corner it says "2 processes running..." or similar, you may just need to wait for that to finish, since it may take time to download all the jars.

Reimport the project. If you install maven plugin you can use this.
Right click on the project -> Maven -> Reimport

I had a similar issue, in my case I am using a custom settings.xml which was not picked from IntelliJ.
Solution:
File > Settings > Build, Execution, Deployment > Maven: User settings file (chose here my custom settings.xml).

IntelliJ 2020.3.3
This one did it for me.
Build, Execution, Deployment > Build Tools.
Change "Reload project after changes in the build scripts":
from default "External Changes" to "Any Changes"
With this, it took a while for the project to rebuild but now I can see Maven dependencies in IntelliJ:

I ran into the problem that some subdependencies couldn't be resolved in IntelliJ 2016.3.X. This could be fixed by changing the Maven home directory in Settings > Build, Execution, Deployment > Build Tools > Maven from Bundled (Maven 3) to /usr/share/maven.
After that all subdependencies got resolved as in previous IntelliJ versions.

In my case, path for JAVA used by MAVEN was not set as JAVA_HOME as configured on the machine. Hence, it was not even trying to download the dependencies.
Steps I followed which solved this issue,
Checked for JAVA path , Settings >> Build >> Build Tools >> Importing >> JDK for importer. Pointed it to JAVA_HOME.
mvn clean install -U
Used above command to force the dependencies download.
Re imported Maven Projects

So I was also facing this problem in lots of my organisation's codebase. On addition to the answers suggested above, we can tweak around with the allocation pool memory of the jvm. This is because, the volume of the dependencies brought in large codebases may be overwhelming for the jvm for IDE to build the project completely. Hence tried increasing XMX value and it worked! Added -Xmx3072 to resolve the issue of "not building" my Java project in IntelliJ

Maven - Reimport did not work for me.
I have Spring project in STS(Eclipse) and my solution is to import project to IDEA like so:
1) File - New - Project from Existing Sources... - select directory - choose Eclipse.
2) Set Maven autoimport to true in settings.
3) Then right click in pom.xml and choose Add as Maven Project.
After this it has imported everything.

I had the similar issue with my macbook, just did a small change in pom.xml and it started downloading all dependencies:
Earlier dependencies were written as below for my windows machine:
<dependencies>
<dependency>
<groupId>javax.mail</groupId>
<artifactId>mail</artifactId>
<version>1.4</version>
</dependency>
</dependencies>
I just removed the <dependencies> and </dependencies> tags and it started downloading all the dependencies:
<dependency>
<groupId>javax.mail</groupId>
<artifactId>mail</artifactId>
<version>1.4</version>
</dependency>
I am not sure it will work for you or not.. but worked fine for me.
Thanks

Deleting the .idea folder from the project directory, and then re-importing the project as a Maven project is what worked for me.

Invalidate Caches worked for me:
File > Invalidate Caches
Checks:
Clear file system cache and Local History
Clear downloaded shared indexes
Then Invalidate and Restart

I solved this issue by updating my settings.xml file with correct mirror config, seems that intellij will try to download meta-data from repository every time the maven module imported.

Hijacking a bit to add what ended up working for me:
Go into the Maven Projects sidebar on the right edge of the IDE, and verify that your dependencies are listed correctly under your module there. Assuming they are, just ask IDEA to reimport then (the first button at the top, looks like two blue arrows forming a counter-clockwise circle).
Once I did that, and let IDEA reload the project for me, all my dependencies were magically understood.
For reference: this was with IDEA 13.1.2

I faced the same problem and tried everything suggested which did not solve the issue, I was using Intellij version 13.1.3
Finally after spending more than couple of hours trying to fix it, I decided to try an upgraded version and opened the project in version 14.1.4 which ultimately resolved the issue. I would think this as a probable bug in the previous version.
I hope this helps!

I was able to resolve it by removing unnecessary modules from Project Settings -> Modules list.
It turns out these additional modules were created automatically by IntelliJ IDEA when I created the IntelliJ project by importing from the project folder (instead of by opening pom.xml). Then, after declaring the project as Maven project, proper modules were created, and existing modules were conflicting with them. It is also possible to exclude those modules during project creation.

In my case, one of the modules was ignored for some reason.
To resolve that: Right click the problematic module and choose "Unignore Projects".

You might be working under a company's internal network.
If so, to download or add external Maven dependencies your settings.xml file under user/<username>/.m2 folder might need to be updated.
Contact your administrator to provide the right settings.xml file and then paste it into you .m2 folder.

Cannot find jar at libraries [duplicate]

I just imported a project from subversion to IntelliJ IDEA 11 - it's a maven project. But I have a problem in maven library dependencies so that I can't include all maven dependencies automatically - IDEA shows dependency errors only when I open that class/ Thats what I get here:
So I want all dependencies to be added automatically - is that possible or do I have to go through all class files to identify and add maven dependencies?!
UPDATE: After doing some modifications I found how to resolve my problem in some way. Thats what I did:
but I think logically it will not include and check new dependencies ahead?!... Is there any settings area for this in intelliJ - auto export dependencies to classpath?

IntelliJ should download and add all your dependencies to the project's classpath automatically as long as your POM is compliant and all the dependencies are available.
When importing Maven projects into IntelliJ an information box usually comes up asking you if you want to configure Auto-Import for Maven projects. That means that if you make any changes to your POM those changes will be loaded automatically.
You can enable such feature going to File > Settings > Maven > Importing, there is a checkbox that says "Import Maven projects automatically".
If that doesn't help, then I would suggest to make a full clean-up and start again:
Close your project window (and IntelliJ) and remove all *.iml files and all .idea folders (there should be one per module)
Run mvn clean install from the command line
Re-import the project into IntelliJ and pay attention when it asks you to enable auto-import
IntelliJ 2016 Update:
The Import Maven Projects automatically setting has been moved to Build, Execution, Deployment > Build Tools > Maven > Importing in your IntelliJ preferences.

Fix before IntelliJ 14
File [menu] -> Settings -> maven -> importing and uncheck "use maven3 to import project"
ref: http://youtrack.jetbrains.com/issue/IDEA-98425 (which may have a few other ideas too)
Fix IntelliJ 15+
Ran into this again, with IntelliJ 15 this time, which has no "use maven3 to import" option available anymore. The cause was that sometimes IntelliJ "doesn't parse maven dependencies right" and if it can't parse one of them right, it gives up on all of them, apparently. You can tell if this is the case by opening the maven projects tool window (View menu -> Tool Windows -> Maven Projects). Then expand one of your maven projects and its dependencies. If the dependencies are all underlined in red, "Houston, we have a problem".
You can actually see the real failure by mousing over the project name itself.
In my instance it said "Problems: No versions available for XXX" or "Failed to read descriptor for artifact org.xy.z" ref: https://youtrack.jetbrains.com/issue/IDEA-128846
and
https://youtrack.jetbrains.com/issue/IDEA-152555
It seems in this case I was dealing with a jar that didn't have an associated pom file (in our maven nexus repo, and also my local repository). If this is also your problem, "urrent work around: if you do not actually need to use classes from that jar in your own code (for instance a transitive maven dependency only), you can actually get away with commenting it out from the pom (temporarily), maven project reload, and then uncomment it. Somehow after that point IntelliJ "remembers" its old working dependencies. Adding a maven transitive exclude temporarily might also do it, if you're running into it from transitive chain of dependencies."
Another thing that might help is to use a "newer version" of maven than the bundled 3.0.5.
In order to set it up to use this as the default, close all your intellij windows, then open preferences -> build, execution and deployment -> build tools -> maven, and change the maven home directory, it should say "For default project" at the top when you adjust this, though you can adjust it for a particular project as well, as long as you "re import" after adjusting it.
Clear Caches
Deleting your intellij cache folders (windows: HOMEPATH/.{IntellijIdea,IdeaC}XXX linux ~/.IdeaIC15) and/or uninstalling and reinstalling IntelliJ itself. This can also be done by going to File [menu] -> Invalidate Caches / Restart.... Click invalidate and restart. This will reindex your whole project and solve many hard-to-trace issues with IntelliJ.

When importing the project, select pom.xml instead of the project directory. It should work.

Try to Re-Import the project from the Maven Projects panel in IntelliJ IDEA. It should download and configure all the dependencies defined in your pom.xml automatically.
If download doesn't work from IDEA for some reason, try mvn install from the command line and see if the dependencies can be fetched.
Of course all the required dependencies and any custom repositories must be defined directly in the pom.xml file.

For IntelliJ 2016-2.4 (and I believe other new-ish versions):
View > Tool Windows > Maven Projects
In the newly revealed toolbar, select Maven settings (icon of a toolset).
When this screen opens, expand the Maven menu and click 'Importing'
Here, click "Import Maven projects automatically." Also ensure that the 'JDK for Importer' option matches the JDK version you mean to use.
Click OK. Now go to the red dependency in your pom.xml, select the red lightbulb, and click 'Update Maven indices'.

What helped me:
Navigage:
Settings | Build, Execution, Deployment | Maven
Specify "Maven home directory" - the place you installed the maven

If certain maven modules are not compiling check if their pom.xml is on the "ignored files" list. In IntelliJ goto
preferences -> project settings -> maven -> ignored files
and check if the related pom.xml is ignored.

I had the same issue and tried all the answers mentioned here, none worked.
The simple solution is go to your project folder and delete all the .idea and .iml files and restart the IntelliJ ide. It works. No need to do anything with the settings.

Open IntelliJ Idea, Go to
File > Other Settings > Default Settings... > Maven (Preferences) > Importing or|
Preferences > Maven > Importing
Click on Enable Auto-import in the console.

When you create a new project you simply need to choose the option:
...
Import project from external model
Create IDEA project structure over existing external model (Eclipse, Maven...)
...
You'll find it pretty straight forward from there.
And in your case you can close your project and simply create a new one. Choose your project's directory, which will override it, making it a Maven project.

Importing Maven dependencies may not work if you import the same path several times. This may happen automatically after importing an existing maven project. I can't figure out why this happens, so I'm inclined to think it is a bug.
For example, if my project is
hibernate
src/main
src/test
the three paths may be imported as top nodes:
hibernate
src/main
src/test
If such is the case, the dependencies appear to be right, but they won't be used until you remove the superfluous paths (in this case, src/main and src/test). Once you do this, refresh and click Build > Rebuild Project. IDEA will pick up the dependencies.
A symptom of this problem is that IDEA warns you of a duplicated path when you manually check a library (second screenshot in the question).
There are several ways to re-read the dependencies in case you need it. If you go to the “Maven Projects” tab, there is a “Reimport All Maven Projects” icon at the top left of the tab. If you suspect IDEA became confused you can click on File > Invalidate Caches.

First check path Specified for User Settings file: in Settings -> Build,Execution,Development -> Build Tools -> Maven .
The field should have path of the settings.xml of your maven. Also the settings.xml should have correct path of remote repository.

Go into your project structure, under project Settings, Modules, select the dependencies table. For each dependency, change the scope from 'Test' to 'Compile'.

If in the lower right corner it says "2 processes running..." or similar, you may just need to wait for that to finish, since it may take time to download all the jars.

Reimport the project. If you install maven plugin you can use this.
Right click on the project -> Maven -> Reimport

I had a similar issue, in my case I am using a custom settings.xml which was not picked from IntelliJ.
Solution:
File > Settings > Build, Execution, Deployment > Maven: User settings file (chose here my custom settings.xml).

IntelliJ 2020.3.3
This one did it for me.
Build, Execution, Deployment > Build Tools.
Change "Reload project after changes in the build scripts":
from default "External Changes" to "Any Changes"
With this, it took a while for the project to rebuild but now I can see Maven dependencies in IntelliJ:

I ran into the problem that some subdependencies couldn't be resolved in IntelliJ 2016.3.X. This could be fixed by changing the Maven home directory in Settings > Build, Execution, Deployment > Build Tools > Maven from Bundled (Maven 3) to /usr/share/maven.
After that all subdependencies got resolved as in previous IntelliJ versions.

In my case, path for JAVA used by MAVEN was not set as JAVA_HOME as configured on the machine. Hence, it was not even trying to download the dependencies.
Steps I followed which solved this issue,
Checked for JAVA path , Settings >> Build >> Build Tools >> Importing >> JDK for importer. Pointed it to JAVA_HOME.
mvn clean install -U
Used above command to force the dependencies download.
Re imported Maven Projects

So I was also facing this problem in lots of my organisation's codebase. On addition to the answers suggested above, we can tweak around with the allocation pool memory of the jvm. This is because, the volume of the dependencies brought in large codebases may be overwhelming for the jvm for IDE to build the project completely. Hence tried increasing XMX value and it worked! Added -Xmx3072 to resolve the issue of "not building" my Java project in IntelliJ

Maven - Reimport did not work for me.
I have Spring project in STS(Eclipse) and my solution is to import project to IDEA like so:
1) File - New - Project from Existing Sources... - select directory - choose Eclipse.
2) Set Maven autoimport to true in settings.
3) Then right click in pom.xml and choose Add as Maven Project.
After this it has imported everything.

I had the similar issue with my macbook, just did a small change in pom.xml and it started downloading all dependencies:
Earlier dependencies were written as below for my windows machine:
<dependencies>
<dependency>
<groupId>javax.mail</groupId>
<artifactId>mail</artifactId>
<version>1.4</version>
</dependency>
</dependencies>
I just removed the <dependencies> and </dependencies> tags and it started downloading all the dependencies:
<dependency>
<groupId>javax.mail</groupId>
<artifactId>mail</artifactId>
<version>1.4</version>
</dependency>
I am not sure it will work for you or not.. but worked fine for me.
Thanks

Deleting the .idea folder from the project directory, and then re-importing the project as a Maven project is what worked for me.

Invalidate Caches worked for me:
File > Invalidate Caches
Checks:
Clear file system cache and Local History
Clear downloaded shared indexes
Then Invalidate and Restart

I solved this issue by updating my settings.xml file with correct mirror config, seems that intellij will try to download meta-data from repository every time the maven module imported.

Hijacking a bit to add what ended up working for me:
Go into the Maven Projects sidebar on the right edge of the IDE, and verify that your dependencies are listed correctly under your module there. Assuming they are, just ask IDEA to reimport then (the first button at the top, looks like two blue arrows forming a counter-clockwise circle).
Once I did that, and let IDEA reload the project for me, all my dependencies were magically understood.
For reference: this was with IDEA 13.1.2

I faced the same problem and tried everything suggested which did not solve the issue, I was using Intellij version 13.1.3
Finally after spending more than couple of hours trying to fix it, I decided to try an upgraded version and opened the project in version 14.1.4 which ultimately resolved the issue. I would think this as a probable bug in the previous version.
I hope this helps!

I was able to resolve it by removing unnecessary modules from Project Settings -> Modules list.
It turns out these additional modules were created automatically by IntelliJ IDEA when I created the IntelliJ project by importing from the project folder (instead of by opening pom.xml). Then, after declaring the project as Maven project, proper modules were created, and existing modules were conflicting with them. It is also possible to exclude those modules during project creation.

In my case, one of the modules was ignored for some reason.
To resolve that: Right click the problematic module and choose "Unignore Projects".

You might be working under a company's internal network.
If so, to download or add external Maven dependencies your settings.xml file under user/<username>/.m2 folder might need to be updated.
Contact your administrator to provide the right settings.xml file and then paste it into you .m2 folder.

Problems with IntelliJ at cloning repo from github

I am new to github. I tried to clone a repo and then pull the files on my computer. All the other team members did the same thing and it worked for them. When i open the project with Intellij all the .java files look like this:
files
It also says that my SDK isn't set.
I tried to set my SDK, and also i tried to set the java directory as 'sources root' because someone said that is a problem with the project structure.
These problems disappeared but then IntelliJ didn't recognize that my project is a maven project so i had to add manually the file pom.xml and refresh maven.
Then this problem disappeared but i had another:
"Cannot start compilation: the output path is not specified for module 'cmsiss'.
Specify the output path in Configure Project."
I tried to set it from project structure but now I have this error:output error
Please help.

Open maven project using pom.xml file. File->Open->pom.xml
Sources should be pointed to project root, not java directory.
Give these a try.

The usual steps that I follow to open the project:
git clone <github clone url>
Open the project in intelli J using
File<Open
and browse to open the root of the project.
This should work fine but if it does not, a few more things you can try:
Try making the project root as a maven module
You can open the Project Structure to make sure you have Java SDK set up properly. It should show the java version you are using there.
Worst case, that is if nothing else works and if the project is not too big, just create a new maven project and make sure it runs, then add all the project files.

I pulled the project again and started from zero. I specified the SDK and then I opened the Maven project window and added a maven project (selected the pom.xml file) and refreshed it. Maven did it's job and created the project structure and all the stuff I've tried to do manually and finally worked!

Maven root pom.xml marked as red when importing existing project into eclipse

When importing existing maven project into eclipse my root pom.xml is marked red.
when i select on the pom.xml the message reads :
Can't import project XYZ from an existing workspace folder
This only happens for the root pom.xml
Eclipse in use: Luna Service Release 2 (4.4.2)
Maven Integration for Eclipse 1.5.2.20150413-2215
I have tested with number of different maven projects and in different workspaces.
Please note this worked before, I have been working on some tutorials and created number of Maven projects with same name and artifact Ids etc. I have deleted all the earlier projects, but could there still be some conflicts ?
any suggestions will help

Yes, You should start your Eclipse Workspace out of the pom.xml folder.
for example: D:\workspace\Project_Name.
In your Project_Name folder which contains pom.xml.
So you have to select D:\workspace while starting the eclipse.
And now, then import the project called Project_Name as maven project, It will work.
Hope, it will help !!

1. In Eclipse select -> File -> Switch Workspace -> Other...
2. The choose one directory up from the the one containing pom.xml
3. Import as Maven the project directory one directory up form the one you are intrested in.
4. Select project of interest from the list of projects.

I also came across this same issue. I kept my eclipse workspace name and existing maven project name same and got the error importing pom.xml. Later i opened new workspace with different name which is not matching to the existing maven project and now i could import maven project.

Solution:
1.Click on Windows tab then Preference(if you are using Eclipse).
2.Search for the Workspaces first and remove all of them from list(which you can add later eventually)
3.Then search for Maven and choose User Setting and check your .m2 path along with the updated setting.xml(meanwhile check the proxy too)
4.After that restart your eclipse and import the existing maven project again.
I'm 100% percent sure u'll no longer face this issue after that. Good Luck :)

I had the same issue while importing the existing spring project to eclipse, what I did is create a new folder as my workspace,
under that I put my spring project,
Then reopen eclipse and gave the workspace location as my newly created folder path
After that,
File -> Import -> Maven -> Existing Maven Projects -> Browser -> (Select the spring project) ->Finish

The problem is the project and the workspace must be two different folder. In my case I have erroneously selected my project folder as my workspace folder and so I was unable import the project.

How to refresh external Jars in Eclipse project (Java)?

I have a Java project in Eclipse which includes a couple of external jar files. These external jar files are being rebuilt through a different process (not Eclipse, Ant). Those changes are not being reflected on the Eclipse project even if I refresh the project. If I close the project and reopen, it works.
Any suggestions on how I could expedite the project without having to close and reopen? Thanks.

Try right click on the project and select refresh.
If that does not work, go to the Project menu, clean, and check your project.

In the package explorer view, you can select the jar and do right click and refresh.
Is not available in Eclipse Version: 3.6.1, Build id: M20100909-0800. I think that version's current. A reportable bug IMHO.
Restarting Eclipse works.

In the package explorer view, you can select the jar and do right click and refresh.

If the above answers did not work for you and this jar is on your build path. Do following steps :
1- remove the jar from the build path(right clicking the jar -> Build Path -> Remove from build path)
2- add the jar to the build path(right clicking the jar -> Build Path -> Add to build path)
This worked for me and is much easier than restarting Eclipse.

If refreshing the project, cleaning the project, refreshing referenced jar (F5) does not work, it might be Maven dependency still referencing old version. If your project uses Maven, remove this jar temporarily from Maven Dependencies list (you can update it later). It worked for me..

I think you should check if you open auto build project option.
Project 、Auto Build Project
Everytime I change the method code block , Eclipse would help me build the project to jar.