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.
Related
Using Eclipse 2018.12, I've installed the Eclipse Kotlin plugin (0.8.20.20200316-1305), created a Kotlin project (using the "New..." options under "Kotlin") and wrote a "Hello World!" program:
Test.kt:
fun main() = System.out.println("Hello World!")
However, when I try to run it I get the message
Error: Could not find or load main class TestKt
Caused by: java.lang.ClassNotFoundException: TestKt
Upon further inspection it seems the class has never been compiled. There is no corresponding .class file anywhere. Under the project directory I see Eclipse configuration directory .settings and files .project and .classpath. Besides that, I have an empty bin directory and a src directory with Test.kt only.
I found two similar questions about this in SO:
In Unable to Run Kotlin Application in Eclipse, the accepted answer simply indicates working with a new version of Eclipse and Kotlin plugin, both older than what I have now. Besides, the problem may have been solved in that case due to a new installation rather than the version.
Kotlin - Error: Could not find or load main class _DefaultPackage is quite old and the accepted answer does not apply anymore. It was about not naming the main class properly, but in my case there is not even a byte code file to be found.
Running "Project -> Compile Kotlin classes" had no effect.
How can I get this simple example to run?
Update: I've updated to 2020-06 (not that it should matter since Eclipse Kotlin lists 2018-12 in its requirements) and replaced Zuly by AdoptOpenJDK HotSpotJDK 11. The error persists. The Eclipse log does not show any related messages.
Update 2: re-created the project in a brand-new workspace but the problem persists.
I used eclipse with jdk 8 to export to jar. Yet i still get this error when start my server sfs
Exception in thread "main" java.lang.UnsupportedClassVersionError: sfs2x/extension/mmo/MMORoomDemoExtension$NPCData has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0
Could someone tell me how to fix.
I tried to uninstalled all java and install jdk8 only. But nothing change.
I had a similar problem, what fixed it for me was making sure that jdk8 was selected as the build jdk for that project (right click on your project in Eclipse and click on properties -> Java build path -> JRE System Libraries -> Workspace Default JRE, make ure that jdk8 is selected) and then recompiling. I was able to delete all .class files before recompiling as well, but that may be difficult if this is a project.
Best of luck.
Actually, after I created the Project in Eclipse, I created a Java class, but it showed an error:
The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files.
I don't know how to resolve this error.
BTW, I have properly installed JDK v1.8 on my computer.
So, please can anyone resolve this problem?
I created a jar file (compiled it using jdk1.7). When I used this jar in a project(using JRE 1.6), I get the following exception- unsupported major.minor version 51.0 (I suppose 51.0 is meant for jdk1.7). I used eclipse IDE for all these operations.
I am wondering whether this exception is a norm (in this kind of situation) or is it coming just because class loading in eclipse works differently
This is expected. Bytecode specifically compiled for a java version, can't be executed on a lower version. This is because it might have bytecode instructions and/or features not supported by an earlier Java version.
To compile for a lower java version, you need to explicitly specify the target version of compilation, eg:
javac -target 1.6 ...
In Eclipse you can set this under Properties > Java Compiler > "Generated .class files compatibility". However in general it is advisable to just use a Java 6 compiler to make sure you are actually only using features and libraries included in Java 6.
Class loading is performed by the JVM, both within eclipse and outside of it. This error simply indicates the the file format of class files has changed in Java 7, and a Java 6 virtual machine does't know the class file format from the future.
You can instruct the Java compiler to use the class file format of a previous java version (in eclipse, you can find the setting under Properties -> Java Compiler -> JDK compliance).
In addition, you'll want to verify that you only use API elements that also existed in JDK 6.
I'm having this exception with some stubs generateds by Axis2:
"The type org.apache.axiom.om.OMElement cannot be resolved. It is
indirectly referenced from required .class files"
I've been reading many posts, and trying to find a solution. What I've found so far is to add the apache tomcat 5.5 library to the build path. It removed the error in the java file, but then, when I to execute any java program inside the project, I got this error:
'Launching myApp' has encountered a problem Exception occurred
executing command line. Cannot run program "C:\Program
Files\Java\jdk1.5.0_22\bin\javaw.exe" (in directory
"D:\Digicel\workspace\Digicel\myClassSample"): CreateProcess error=87,
The parameter is incorrect
then if I remove the apache tomcat library from the build path, I can run the other java programs, but not the one mentioned initially.
Any thoughts about it?
Okay, I've found the cause of the problem with the help of a friend :)
The thing is that Eclipse is aware that one of my dependencies, depends of another library, and Eclipse is checking for it when it tries to build the code.
So, what I've done is try to check which jar file contains this library: " org.apache.axiom.om.OMElement".
I've googled it and found that it is "axiom-api-1.2.10.jar" and finally my file compiled with 0 errors.
He also explained to me that my original solution of adding the apache tomcat server library is adding all the jars that cames with apache tomcat (which is a big list), and probably there may have been a version conflict with my current list of added jars.
So, the fix was to find the appropriate jar and add it to the project.
This error can also occur when a indirect dependency has a corrupt jar file. This may be caused by problems at the public maven repository.
If this is the case removing the local maven repository to download fresh jar files will fix your problem:
rm -Rf ~/.m2/repository/{enter/path/to/broken/stuff}
Goto Maven >Update Maven project>checkmark the Force update >Then Run
..That error Will gone....