Eclipse Compilation Error - eclipse

I imported some JTB and JavaCC generated files into Eclipse and there is one line giving me an error - the first line (a comment) most of the class files says "The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files" How do I fix this?

Have you tried removing and adding the JRE in your project?
Select Project -> Properties
Select Java Build Path
Navigate to the Libraries Tab
Remove the JRE
Click Add Library and add the default JRE again
PS: Project -> Clean can be very useful, too.

Related

Error: scalac: error while loading package, Scala signature package has wrong version; expected 5.0, found 5.2 in package.class

I have a java & scala project that I am updating jars for.
I swapped out akka-camel_2.11.jar and replaced it with jar akka-camel_2.13-2.5.25.jar, and now I see the error shown in the title when attempting to build in Intellij.
What is the scala signature? What is package.class?
And how might I edit these so that my project can build using this updated jar?
When you have multiple versions of dependencies of same SDK it show this error
I too faced this issue.
my scala project had the following dependencies
org.scala-lang:scala-library.2.11.0 [as well as]
org.scala-lang:scala-library.2.7.0
so this caused the confusion with the signature.
remove one of the added library .
in intellij idea
files -> project structure -> library tab -> scroll and search for the extra added library -> press the '-' icon at top left side of the dialog box.

I couldn't build Jhipster sample app

I'm trying to run Jhipster sample app in my Eclipse kepler . I've downloaded the project from here and I've imported it as existing maven project but it couldn't be build . I got this exception :
The type java.util.Optional cannot be resolved. It is indirectly referenced from required .class files AccountResource.java
and many "Undefined CSS file" errors
how can I run this project in my Eclipse ?
Normally you should create your application using the yeoman generator. Install yeoman and execute yo jhipster from your command line.
a)For the java exception basically you need to remove the old version of java from your build path and add support for java 8.
You need to follow these steps
1) Right-click on project » Properties » Java Build Path
2) Select Libraries tab
3) Find the JRE System Library and remove it
4) Click Add Library... button at right side » Add the JRE System Library(Workspace default JRE)
Do not forget to set the Java jdk compiler compliance level to 1.8 (Preference -> Java -> compiler )
b) The jhipster site mentions about the configuration settings(css,javascript and html etc)for eclipse to avoid errors in eclipe. https://jhipster.github.io/configuring_ide_eclipse.html

build paths eclipse java j2ee

I have imported a project (I am very new at this) and I get the following errors:
Project cannot be built until build path errors are resolved
Project FST is missing required library: 'C:program Files/Apache Group/Tomcat 4.1/common/lib/servlet.jar'
Project FST is missing required library: 'C:program Files/Apache Group/Tomcat 4.1/common/lib/struts.jar'
The project cannot be built until build path errors are resolved
Unbound classpath variable: 'TOMCAT_HOME/common/lib/jasper-runtime.jar' in project
Unbound classpath variable: 'TOMCAT_HOME' in project FST
I create a variable called TOMCAT_HOME and give it the proper directory ,but Also, we should change the project classpath to use TOMCAT_HOME rather than the absolute path.
i dont know how to do it (change the project classpath and the absolute path)
thanks !
To answer somewhat indirectly, if you configure your project build with something like Maven or Gradle, so that you can successfully build the project using the corresponding command-line tool, then it should be quite straightforward to import the project into eclipse using the Maven or Gradle eclipse plugin. I think doing so will be worth whatever trouble it causes you in the short run--just take care to make your project structure conform to the usual project structure that Maven expects or you'll be asking for trouble (it should be no problem to do so for greenfield work).

Error message nutch eclipse

I am trying to build nutch 1.4 from the source code within eclipse env. Everything is ok but I receive an error message in class org.apache.nutch.util.domain.TopLevelDomain.java that says
The type java.lang.Object cannot be resolved.
It is indirectly referenced from required .class files
What could be the reason when Object is the main class and Libraries for JRE are included.
Your project needs to point to a valid JRE, which itself needs to be properly set up n the Installed JREs preference page.

How do you ensure a Utility Projects library dependency gets packaged in the final EAR in Eclipse Galileo?

I have a 'Utilty Project', and an 'EAR Project' that includes that 'Utility Project'. All the classes from the 'Utility Project' end up being packaged as a JAR and placed within the 'lib' directory of the exported EAR, for example:
EAR.ear
META-INF
MANIFEST.MF
lib
utility.jar (which expands to):
META-INF
MANIFEST.MF
com
acme
Foo.class
Bar.class
However, the 'Utility Project' relies on a library (freemarker.jar) that has been added to the build path using 'Properties > Java Build Path > Libraries'. All I want to do is to get freemarker.jar added to the EAR as follows:
EAR.ear
META-INF
MANIFEST.MF
lib
**freemarker.jar**
utility.jar (which expands to):
META-INF
MANIFEST.MF
com
acme
Foo.class
Bar.class
By searching around within Eclipse I've found 4 potential avenues for achieving this, none of which have worked. If someone can just cut to the chase and tell me what I should actually do, that would be great. But just in case, I'll iterate them here:
From the 'Utility Project' Properties:
If I click 'Java Build Path > Order and Export' and select 'freemarker.jar' for export, the jar does not end up in the EAR file at all.
If I click 'Java EE Module Dependencies' and select the 'freemarker.jar' library as a dependency, it says:
This JAR is a bundled library of an
EAR project and is supposed to be
packed in the EAR's library directory.
It conflicts with the manifest class
path dependency you are trying to
create. If you create this dependency,
the JAR will be packed in the root
(not library) directory of the EAR.
Are you sure you want to proceed?
From the 'EAR Project' Properties:
If I click 'Java EE Module Dependencies > Add JARs...' and navigate to the 'freemarker.jar', and make it a dependency, it gets added to the root of the EAR:
/freemarker.jar
If I do the same as above, but check the 'In Lib Dir' checkbox, it gets added into the lib folder, but contained within another lib folder:
/lib/lib/freemarker.jar
Thanks.
I've managed to solve this problem. In the Problems window I was getting the following warning:
Classpath entry /utility-project/lib/freemarker.jar will not be exported or published.
Runtime ClassNotFoundExceptions may result.
What I tried, at a whim, was to use the Ctrl-1 key combination I've been using to get quick fix solutions for my source code. It turns out this also provides quick-fix solutions for for the given errors and warnings. I chose the first of the two options:
Mark the associated raw classpath entry as a publish/export dependency.
and my problem disappeared!
Bizarrely, all this seems to have done is to cause the 'freemarker.jar' lib to be selected in the 'Java EE Module Dependencies' properties dialog, which I was doing myself anyway. This may be an Eclispe bug!
#MonoThreaded: After using the quick fix > Mark the associated raw classpath entry as published/export dependency, if you right-click on the project > properties > depolyment assembly you will notice that eclipse has added a new entry, something like source: /freemaker.jar, deploy path: ../lib. You can do that too, by selecting Add > Java Build Path Entry.