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I use eclipse with maven integration for my java web application project. When you right click the project you can "refresh" the project. You can also use "maven -> update project". What is the difference between refresh and update?
Sometimes I got a red-x sign in my pom file (I don't think there is any error). When I use the "refresh", the red-x sign disappears. Any idea?
Another question is that when I update the project, in the property -> deployment assembly, the maven dependencies was removed (I manually added them when I created the project). How can I fix this?
Thanks
A quick google search yielded this result: What does Maven Update Project do in Eclipse?
The correct answer states:
It syncs the Eclipse project settings with that of the pom. If you for example change important plugin settings, such as the output java version, you will find that Eclipse will ask you to update the project and afterwards the configured Java runtime in the project will have changed to reflect what your Maven pom indicates. That is an important thing to keep in mind: the Maven pom is the lead in this kind of project setup. If you want settings to change, try to do that through the pom and not through Eclipse project settings directly or doing a project update might revert what you have changed. There are usually some things I have to correct myself anyway though, such as build path exclusions that m2eclipse likes to put in and strange deployment assembly configurations.
So in short,
Updating your project through maven synchronizes the settings with that of pom and keeps all the settings synchronized between the pom and the project.
Refreshing your project through eclipse will reload the project - that is reload all the files and apply any external changes from the files to the project.
Note that a maven update will cause a refresh of the project in eclipse.
FYI, here's what the official documentation states:
Refresh command
The official Eclipse Oxygen documentation has two distinct (yet similar) definitions:
In Workbench User Guide > Reference > User interface information > Workbench menus > File menu it reads
Refresh (F5)
Refreshes the resource with the contents in the file system.
In Java development user guide > Reference > Menus and Actions > File actions it reads
Refresh
Refreshes the content of the selected element with the local file system. When launched from no specific selection, this command refreshes all projects.
F5
Update Project command
Unfortunately, the only documented occurrence I have found in m2e documentation (see m2e 1.5 release notes) is utterly insufficient and barely related:
The Update Maven Project dialog (launched via Right-click project menu:Maven[Update Project…] or via kbd:[Alt-F5]), now shows a dirty overlay on projects which need updating.
Additionally, an “Add out-of-date” button adds all out-of-date (OOD) projects to the current selection. If an OOD project has not been selected, a warning is shown underneath the selection table with a link equivalent to “Add out-of-date”. Warning text and “Add out-of-date” button tooltip show a count of unselected OOD projects.
Related questions on the 'Update Project' command (or the 'Update Maven Project' dialog):
(Which, alas, however insightful the best answers are, still provide no official statement from m2e developers.)
https://stackoverflow.com/a/20547404/4883320
https://stackoverflow.com/a/42562054/4883320
I have a main method in a package in one of my projects. Say, the package is com.ant.car. I am trying to run and/or debug this main method, and I keep getting the error Could not find or load main class com.ant.car.
I've searched this problem, and it seems like I can't figure out what is wrong.
1) I've checked run configurations. In Run->Run Configurations, I've checked that the Main class is com.ant.car.
2) I've checked build path. If I right click on the project, I select Build->Build Path, and under the Libraries tab I make sure there are no missing folders with red Xs next to them.
Not really sure what else to do. Any suggestions?
Project -> Clean
this is working
Try updating project by right clicking on it. Maven -> Update Project
Today I ran into the same problem and I tried a lot of answers. Nothing helped. Cleaning the project, build automatically is already checked, deleting .metadata, etc.
Eventually I tried this and it worked perfectly:
menu Project -> Properties
Java Build Path, tab Libraries
Remove the JRE System Library from there, press Add Library, take the JRE System Library and press Next. Workspace default JRE and press Finish.
What worked for me:
Menu Project -> Properties
In Java Build Path, tab Libraries
Delete all libraries with a red [x] next to them.
In my case, problem happened when I switched from Kepler to STS IDE.
The solution to this was the following:
Close Eclipse/STS
Use a file explorer on your operating system to navigate to your workspace (In my case, I'm on Windows so I used Windows Explorer)
Delete the .metadata directory (or to be safe, copy the directory somewhere else to be safe, then delete it)
Restart Eclipse/STS
Is there a more improved answer than this? I don't want to look like I'm trying to boost my own reputation points, so if someone can provide a better answer then please do so.
Sometimes the problem can be caused by some newly added dependencies. Try removing the recently added jars. That's how I fixed my problem.
Project -> Clean... -> check project not working -> Clean
I already had build automatically set, but forcing STS to rebuild it fixed it.
This issue occurs when the main .class file moved or not found because you changed the directory for committed/shared the project into the git or another repository.
To Resolve this issue -->
Remove existing run configuration and new one.
Find the parent pom.xml or project pom.xml and open cmd/command prompt and run the below commands,
mvn clean install package
mvn eclipse eclipse
It worked for me:
1. Delete metadata from work-space directory.
2. Import the project again, but selected copy to work-space option.
I think the cause for the error was Non-English characters in the original saved directory.
You just need to delete Run Configuration file and restart STS and run command -mvn clean install and try to restart the service
The Error "Could not find or load main class com.ant.car" occur when your class is not in build path. please make sure that .class file is generated and it's in build path ..
I faced the same issue..
just do follow these steps:
STS/Eclipse --> Project --> Enable "Build Automatically"
then refresh your project, it will resolve your issue.
Still not refreshed your projects automatically, just restart your STS and check.
Hope it will help you.
I think .class files are deleted/missing from JavaProject/bin folder.
To resolve this issue ->
1) Just cut paste and save the code contents of all the files that you are using then .class files will be regenerated.
2) Then run the code and you can see it works fine if there is no syntactical errors.
1 ) Clean the Project
2 ) Enable build automatically Option
3 ) Update the maven project by use the short cut Alt + F5
Deleting target folder manually and mvn clean install worked for me
A quick and easy fix is to directly run your SpringBootApplication class (i.e. Right click, Run As -> Spring Boot App). This runs the app and creates a run configuration automatically.
I spent several hours on this issue, finally it is fixed by doing this:
Properties -> Java Compiler: uncheck the checkbox "use '--release' option"
This worked for me to solve the error. (I got this error after removing AWS ToolKit)
Close the Eclipse/ STS Eclipse.
Go to the WorkSpace folder.
Delete the .metadata folder.
Open the eclipse.
Run maven install on pom.
Run the project with your Run configuration.
Remove project from STS/Eclipse
Close or Refresh the Eclipse/ STS Eclipse.
Run maven install on pom.
Run the project with your Run configuration.
Tried above mentioned steps to resolved issue.
You can try one of the two solutions below:
Solution 1: Right click the project -> Gradle -> Refresh Gradle Project.
Solution 2: Add gradle or maven in your environment variable. My problem was that I had not added gradle in my environment variable. Before, make sure Gradle or maven is installed in your OS.
I tried all the answers but finally what worked for me was deleting the project from eclipse workspace and importing it again.
I have just got a new computer and installed Eclipse Indigo and all of the plugins that I use. But when I open my workspace from my old computer some projects have an exclamation mark.
What does a red exclamation mark mean on a project folder?
The red exclamation mark usually means there is a problem with the Build Path.
Do you see any alerts in the "Problem" View?
It means that there is an error on that project..
You can look at all the errors in the Problems tab. press ALT SHIFT Q followed by X to
show this tab.
It means that there are two things happened.........
What ever jar file or project setup jar file for your application
are not located at that point where it was earlier in your computer.
So that First you have to setup your project with all the jar files
and refresh it.
Check syntax in your project might be some mistake in that.
The red exclamation mark in eclipse is because of the problem/issue with the build path.
To find the specific issue look at the problems tab of the eclipse.
Window -> Show View -> Problems (or) Alt+Shift+Q,X
If you didn't find any error on the project files, usually it means your build path has some issue. First Check your jar file and jar file locations.
On eclispe, right click on your project, Go to build path and go to Configure build path. Check any errors under libraries. Configure it correctly and refresh the project.
It appears mostly because of "build path" only. But just in case you are working on a MAVEN project, here is the solution.
Solution
Step 1. Expand your project in Eclipse > Right click on "JRE System Library" > "Build Path" > "Remove From Build path"
Step 2. Expand your project in Eclipse > Right click on "Maven Dependencies" > "Build Path" > "Remove From Build path"
Step 3. Reach out to your local repository and follow below path "C:\Users\userName\.m2\repository" and delete everything inside repository folder
Step 4. Refresh your project in Eclipse
Step 5. Right Click on your project > "Maven" > "Update Project"
Step 6. Just refresh your project and now we are Ready to GO..
In my case show hidden files was enabled and i had added hidden jar file extensions along with the original jars. Adding only the jar files except the hidden files solved the problem
It can appear when any other file other than .jar is added in the jar library. To fix this, remove the file and clean the project.
If it is maven project and your project view having no error. Then try the following steps
Right click the project ---> maven --> update maven
It works for me.
What the error means is that the Java (JDK) version installed needs an update, as the older version could not be read. To rectify the issue, uninstall your Java (JDK) and install the latest version. Restart eclipse and the would be seen resolved.
This may help in case your build path is correct and you have put the right signature and access specifier for main, so maybe used as a hook to try before you make any modifications to your build path.
Just go to your problems bar and delete the problem given for the project, clean the project and build it. It should solve the problem, if these steps cause the red exclamation to go away.
I am trying to run my project, but Eclipse is saying I have errors. But there are no errors, just a red cross where the project name is. I have tried deleting the R.java and generating a new one, but that didn't work.
Take a look at
Window → Show View → Problems
or
Window → Show View → Error Log
Based on the error you showed ('footballforum' is missing required Java project: 'ApiDemos'), I would check your build path. Right-click the footballforum project and choose Build Path > Configure Build Path. Make sure ApiDemos is on the projects tab of the build path options.
This happens from time to time in Eclipse. In the "Project" menu there's a "Clean" option, that usually takes care of the problem.
Go to project>clean and select the project which display error from check box and click ok , it will clear the error for you.
Click the tab which display build automatically in the project menu
And if this also does not work than restart the eclipse and try again it will work.
For me, this happens with Maven and Eclipse/STS whenever I update my IDE or import an existing Maven project. Go to the "Problems tab" (Window -> Show View -> Problems) and see what it says. Recently, the problems tab showed Project configuration is not up-to-date ... and suggested that I use Maven to update my project configuration, and this solved the "red X" problem. To do this, in the "Project Explorer" view, trigger the context menu and select Maven -> Update Project, as seen in this screenshot:
If you see the error in problem panel it will say : Description Resource Path Location Type
Project configuration is not up-to-date with pom.xml. Select: Maven->Update Project... from the project context menu or use Quick Fix.
Solution : Right click on project > select : Maven->Update Project
Error gone.
Right Click on Project -> Build Path -> Configure Build Path. Check if Maven Dependencies is there in list, if not then update maven project by
Right Click on Project -> Maven -> Update Project
I had a red X on a folder, but not on any of the files inside it. The only thing that fixed it was clicking and dragging some of the files from the problem folder into another folder, and then performing Maven -> Update Project. I could then drag the files back without the red X returning.
Ensure you have Project | Build Automatically flagged. I ran into this issue too and turning that on fixed the problem.
I just removed all the private libraries in JavaBuildPath and added the jars again.. It worked
I came across the same issue while working on a selenium project(maven). The Project folder and pom.xml were showing red cross symbol. This was coming as i had the test datasheet open. I could remove the error by just closing the datasheet and the never faced the issue again
In my Spring Boot application, I right-clicked on my Application class -> run as -> Java Application -> Proceed(All errors will be cleared)
For some reason Eclipse is no longer showing me Java compilation Errors in the Problems View.
It is still showing Warnings.
This has suddenly happened and I cannot think of anything that I have changed which would affect this.
I am using the "Maven Integration for Eclipse" plugin but I have been for some time - not sure if this could have affected it or not.
Any ideas?
I had same problem and randomly did such things as (several times):
1) Project->Clean...,
2) close and open Eclipse again,
3) Run As...
And it started to work again, without changing configuration.
Right-click your project and go to Properties > Java Build Path > Source.
Make sure your source directory (for example MyProject/src) is listed as a Source folder. Otherwise you won't get any red markers.
I want to post my story here if Google brings you to this question.
Somehow, "Project->Build Automatically" got turned off.
Turning it back on produces correct errors list.
In my case it has nothing to do with m2e 1.0. This is default behavior for any Java project and goes back as far as Ganymede ( at the point of writing this post I am running Indigo )
This is not totally an answer to your question, but is related. I thought eclipse stopped showing red/yellow flags next to files in my project. The solution was very simple - I was looking at the Navigator tab (which doesn't show error/warning flags) instead of the Package Explorer tab.
I installed and deinstalled ajdt-plugin and got the same problem.
Check <Project><Properties><Builders>.
It should have a 'Java Builder'.
This code should be in the .project file (file is in the root of your project):
<buildSpec>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.eclipse.jdt.core.javanature</nature>
</natures>
Check your source directory is listed in source folder of project
Right-click your project > Build Path > Configure Build Path > Source.
If you are using multiple projects (as dependencies)
Project->Clean...,
Check "Build Automatically" is enabled or not.
project > Build Automatically
What worked for me is creating a New Problems View (this option is accessible from the three-dots View options):
The new View does show all the warnings and errors that were detected:
I was experiencing this problem as well today. The other solutions presented here (such as cleaning the project and restarting Eclipse) did not work or were not applicable to my setup. What did work for me was right-clicking on the project in the Package Explorer and selecting Maven->Update Project Configuration. Evidently some source folder restructuring I had done the previous day had caused Maven to lose track of things, and issuing this command fixed everything.
At the top right corner of the problems window (next to minimize) there is a small arrow-icon. Click it and select "Configure filters". There is a severity filter that might have been activated.
I have the same problem in slight different situation. I have a parent POM and multiple modules under it. Project was existing and I imported it into eclipse. I can change the "Dependency management" only to parent project but not projects under it. They are not showing any compilation warnings.
Next I'm going to try to change them all into individual projects... that's not what I wanted, but I haven't been able to solve this otherwise...
I have also faced the same problem.
After installing m2eclipse plugin, i was not getting any Java compilation errors.
My solution was to enable dependency management by Select Project -> Right Click (to get context menu) -> m2 Maven -> Enable dependency management.
Now i am able to view Java Compilation Errors.
This is normal problem. In wich order and export function sometimes get turned off.
right click on project<properties< there u hav option
build path < and there ORDER AND EXPORT< click right all the options....all the things are right back.
On Ganymede, check the configuration of the Problem view:
('Configure content') It can be set on 'any element in the same project' and you might currently select an element from the project.
Or it might be set on a working set, and this working set has been modified
Make sure that 'Match any configuration' is selected.
In my case Eclipse wasn't properly picking up a Java project that a current project was dependent on.
You can go to Project > BuildPath > Configure BuildPath and then delete and re-add the project.
There are obviously several reasons why this might occur, and I thought I'd add the solution to my issue. (I have a java project into which I have imported files with virtual links)
If you have a situation like mine, you will have another folder on the same level as your 'src' folder. If you do, right-click on that other folder, then select 'Build Path' > 'Add to Build Path' (if you see 'Build Path' > 'Remove from Build Path', then it had already been added.)
To further configure the Build Path, right click on your top level project dir, and select 'Build Path' > 'Configure Build Path'. Your folders should show up in the 'Source' tab.
To configure what errors you see, Click on Java Compiler > Errors/Warnings and then click 'Configure Workspace Settings'. That is the same as going to Window > Preferences > Java > Compiler > Errors/Warnings. If you don't want Eclipse to ignore something, then just change it to Warning.
Try following:
Open Problems window (Windows -> Show View -> Problems)
Right click on the error and then Quick Fix
This procedure helped me solve the same problem.
If you have reached here that means all the other solutions did not work for you.
One reason could be your source folder is not a java project.
Solution would be to run below command on the source folder
mvn eclipse:eclipse
This worked for me.
If this also doesn't work then try removing .classpath and .project file and run the above command again
I could reproduce this issue by creating an enumeration with a non-static member class and a static block enumerating its values:
public enum Foo {
Dummy(new Bar [] {new Bar()});
static {
for (Foo foo: Foo.values());
}
private Foo(Bar [] params) {}
public class Bar {}
}
This class breaks the Ganymede compiler. If you delete the line in the static initializer block, the code compiles correctly again, and you get the error that there is no enclosing instance for the new Bar() call, as expected.
-- correction: The above holds only if the project has gaeNature from Google Appengine. However, if you get an error similar as mentioned in the original question, you might be encountering another java compiler bug ...
I have the same issue with Eclipse Helios and the m2eclipse plugin. They just can't seem to get this thing to work with WTP or WPT or whatever the blasted acronym is.
If I do a clean on the project and watch the Maven console then I can see the compilation issues in the console but eclipse won't touch it. It seems eclipse or WTP/WPT and m2eclipse are busy playing slap hands.
I experienced that problem with a MapReduce project. I closed the error window and never came back after doing what the other answers suggested.
Click on the bottom left -> Other -> Problems
Kepler SP2, Java Project (Web Driver), and we use Gradle instead of Maven
None of the above helped, what did fix the problem for me was to select my projects (r-Click) > Gradle > Refresh All
Pointing the source(src) folder to the build path will solve this easily
to do so
right click on the project > build path > configure build path > java build path > source > add folder and click Apply
My mistake was that I was creating classes in resource package...
Creating classes in src/main/java solved the issue.
Check your filters, sometimes problem view could be scoped to a working set that you are not currently working in. Also, you can check other configurations for the problem view.
Problem in .classpath
I did "Replace with HEAD revision" to get back the version that I had in the repository Git and the errors appear again.
Duplicates in build path
In my case, errors were not showing up in the Problems View or Package Explorer views because my build path had duplicate entries for src and test directories:
Removing these from Project -> Properties -> Build Path (and just leaving one each) did the trick.
In my case I setted a old workspace and it was the problem.
Try to set a new folder for workspace
If "Debug" has been recently activated then check the top right of the program (under the Minimise button) and click back onto Java.