Develop Reference

Force IntelliJ project to use Scala compatible with Java 6

I have this project in IntelliJ IDEA which uses Scala. I need it to be compatible to run on Java v1.6. I configured the project as such, and I even only have Java 6 in my development environment. However, when I build the project and run it I get the following:
Exception in thread "main" java.lang.UnsupportedClassVersionError: scala/Function1 : Unsupported major.minor version 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:637)
at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at myproject.Main.main(Main.scala)
It appears as so there's still some class in my project compiled for Java 8. Could it be that the Scala libraries I have are compiled for Java 8? These are the libraries downloaded by IntelliJ IDEA. How can I solve this?

connect to server socket running in eclipse

I want to connect a Client written in Perl and running via command line to a server written in java and running in Eclipse. It don't work, it's because the server is running in Eclipse ? when I try to run the server via command line I got an error, but in eclipse it work fine
java MultiThreadServer
Exception in thread "main" java.lang.NoClassDefFoundError: MultiThreadServer (wrong name: inet/MultiThreadServer)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

I think that is a classpath issue.
The NoClassDefFoundError indicates that the classloader can't find the .class file that you're trying to use. You should set the classpath when executing your code.
See
Classpath in Java

hadoop wordcount Unsuppored Major.Minor version 51.0 ERROR

I created a jar file for wordcount in Hadoop 1.1.1 while running world count its giving me following error:
hduseros#MT2012018:/usr/local/hadoop$ bin/hadoop jar playground/wordcount.jar org.apache.hadoop.examples.WordCount /user/input/playground /user/output1
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/hadoop/examples/WordCount : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at org.apache.hadoop.util.RunJar.main(RunJar.java:149)

This error comes when your hadoop system is running lower Java version than the one used to compile your MapReduce code.
Check java versions of your hadoop system and system you used to compile your code with "java -version".

The error is because of jdk mismatch on the machine which you are compiling and the machine on which you are running the jar. Match both the versions of jdk.

StackOverFlowError when using SAXReader after Java security update

Running a Mac (OS X 10.8.1). We were upgraded to the latest Java security update 1.6.0_35-b10-428 and since then our main app doesn't launch in Eclipse.
The Exception below is thrown when starting up Openfire 3.6.4. Pretty much where the openfire.xml config is parsed is when the error occurs:
private void buildDoc(Reader in) throws IOException {
try {
SAXReader xmlReader = new SAXReader();
xmlReader.setEncoding("UTF-8");
document = xmlReader.read(in);
}
catch (Exception e) {
Log.error("Error reading XML properties", e);
System.out.println("NOOO");
e.printStackTrace();
throw new IOException(e.getMessage());
}
finally {
if (in != null) {
in.close();
}
}
}
Exception thrown:
Exception in thread "main" java.lang.StackOverflowError
at java.nio.HeapByteBuffer.<init>(HeapByteBuffer.java:52)
at java.nio.ByteBuffer.wrap(ByteBuffer.java:350)
at java.nio.ByteBuffer.wrap(ByteBuffer.java:373)
at java.lang.StringCoding$StringEncoder.encode(StringCoding.java:237)
at java.lang.StringCoding.encode(StringCoding.java:272)
at java.lang.String.getBytes(String.java:946)
at java.io.UnixFileSystem.getBooleanAttributes0(Native Method)
at java.io.UnixFileSystem.getBooleanAttributes(UnixFileSystem.java:228)
at java.io.File.exists(File.java:733)
at sun.misc.URLClassPath$FileLoader.getResource(URLClassPath.java:999)
at sun.misc.URLClassPath.getResource(URLClassPath.java:169)
at java.net.URLClassLoader$1.run(URLClassLoader.java:194)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at org.dom4j.DocumentFactory.createDocument(DocumentFactory.java:102)
at org.dom4j.DocumentFactory.createDocument(DocumentFactory.java:122)
at org.dom4j.io.SAXContentHandler.createDocument(SAXContentHandler.java:830)
at org.dom4j.io.SAXContentHandler.getDocument(SAXContentHandler.java:164)
at org.dom4j.io.SAXContentHandler.comment(SAXContentHandler.java:428)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.comment(AbstractSAXParser.java:667)
at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.comment(XMLDTDValidator.java:978)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:479)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:808)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:119)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
at org.dom4j.io.SAXReader.read(SAXReader.java:465)
at org.dom4j.io.SAXReader.read(SAXReader.java:365)
at org.jivesoftware.util.XMLProperties.buildDoc(XMLProperties.java:471)
at org.jivesoftware.util.XMLProperties.<init>(XMLProperties.java:114)
at org.jivesoftware.util.XMLProperties.<init>(XMLProperties.java:63)
at org.jivesoftware.util.JiveGlobals.loadSetupProperties(JiveGlobals.java:832)
at org.jivesoftware.util.JiveGlobals.getXMLProperty(JiveGlobals.java:282)
at org.jivesoftware.util.JiveGlobals.isSetupMode(JiveGlobals.java:791)
at org.jivesoftware.util.JiveGlobals.getProperty(JiveGlobals.java:529)
at org.jivesoftware.openfire.XMPPServer.initialize(XMPPServer.java:300)
at org.jivesoftware.openfire.XMPPServer.start(XMPPServer.java:419)
at org.jivesoftware.openfire.XMPPServer.<init>(XMPPServer.java:163)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.Class.newInstance0(Class.java:355)
at java.lang.Class.newInstance(Class.java:308)
at org.jivesoftware.openfire.starter.ServerStarter.start(ServerStarter.java:106)
at org.jivesoftware.openfire.starter.ServerStarter.main(ServerStarter.java:51)
Edit: Added Xss1m as suggested, but whilst the application got further I'm seeing the same error. Here's my startup args:
here's my startup args:
-DopenfireHome="${workspace_loc:openfire}/target/openfire" -Djava.net.preferIPv4Stack=true -Xms32m -Xmx512m -Xss1m -XX:ThreadStackSize=128 -XX:PermSize=72m -XX:MaxPermSize=96m -XX:+PrintGCDetails -Xloggc:/tmp/gc.log -XX:+HeapDumpOnOutOfMemoryError
Edit2:
Seems the below amendments work:
amending -Xss128k to -Xss1m and removing -XX:ThreadStackSize=128

Did you try increasing stack size? You can do it by specifying -Xss1m when starting JVM. In the example JVM will allocate 1 Megabyte for stack for each thread. Be careful not to use too big a value as it will be multiplied by the number of threads in your application.
To change configuration in Eclipse, please follow these steps (copied from here).
Open the Run Configuration for your application (Run/Run Configurations..., then look for the applications entry in 'Java application').
The arguments tab has a text box Vm arguments, enter -Xss1m (or a bigger parameter for the maximum stack size). The default value is 512 kByte.
EDIT:
It looks like it's a common issue. Security patch probably introduced another method call to the chain and all projects that used to fit into the stack don't fit anymore.

How to run a project that written in NetBeans on another computer?

I wrote a project in NetBeans IDE in my computer, and I ran it. That was OK. I transferred it into my Friend's computer. I ran it with NetBeans, but I got these errors:
java.lang.UnsupportedClassVersionError: friendspro/Server/RunServer : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
Could not find the main class: friendspro.Server.RunServer. Program will exit.
Exception in thread "main" Java Result: 1
///
When I ran my project in my computer in CMD, I got the same error:
C:\Users\Blue\Desktop\FriendsPro\src\friendspro\Server>java RunServer -ORBIniti
alRef NamingServic=corbaloc::localhost:1049/NameService
Exception in thread "main" java.lang.NoClassDefFoundError: RunServer (wrong name
: friendspro/Server/RunServer)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14
2)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:476)

It's not the same error. Your friend has an older Java version. Here's how to target older Java versions in NetBeans: Target JDK for Java Applications.
You are running your program incorrectly. You need to do
java friendspro.Server.RunServer -ORBIniti ...
in your main directory (probably bin or src).

On your computer, open CMD, cd to your source directory and then, as Banthar specified,
java friendpro.Server.RunServer ...