Develop Reference

Travis CI: java.lang.UnsupportedClassVersionError

I am trying to setup CI for https://github.com/amCap1712/pljava using Travis. But it fails with following log:
find pljava-packaging -name \*.jar | sudo xargs java -jar
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/gjt/cuspy/JarX has
been compiled by a more recent version of the Java Runtime (class file version 53.0), this
version of the Java Runtime only recognizes class file versions up to 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:757)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:468)
at java.net.URLClassLoader.access$100(URLClassLoader.java:74)
at java.net.URLClassLoader$1.run(URLClassLoader.java:369)
at java.net.URLClassLoader$1.run(URLClassLoader.java:363)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:362)
at java.lang.ClassLoader.loadClass(ClassLoader.java:419)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
at java.lang.ClassLoader.loadClass(ClassLoader.java:352)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:495)
The complete build log and travis config is available at https://travis-ci.org/github/amCap1712/pljava/builds/661687014 . I am using OpenJDK9 for this build but it fails for OpenJDK14 as well.
How to fix the error ?

ClassNotFoundException Error any ideas?

I am new to Java and I get this error for my code:
C:\Users\Unknown\Desktop\AIB>java GreenhouseControls -f examples1.txt
Restarting system
java.lang.ClassNotFoundException: ThermostatNight
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at GreenhouseControls$Restart.action(GreenhouseControls.java:139)
at tme3.Controller.run(Controller.java:32)
at GreenhouseControls.main(GreenhouseControls.java:197)
I believe I have a classpath errors.

Did you try to add your compiled java files (i.e., Event.class, ThermostatNight.class, ...) of Event.java, ThermostatNight.java to the classpath:
java -cp "target/*" GreenhouseControls -f examples1.txt
I assume that your compiled class files are in the target directory.

I solved in this way.
java -classpath YourProjectWar.jar com.yourpackage.ClassWithMain -f examples1.txt

Java classpath issue with external jars

I am having issues compiling external jars along with my source code. My .java files and the external jar reside in the same directory. Here is my makefile:
JFLAGS = -g
JC = javac -cp ${CLASSPATH}
.SUFFIXES: .java .class
.java.class:
$(JC) $(JFLAGS) $*.java
CLASSPATH = *.jar
CLASSES = \
AESCBC.java
default: classes
classes: $(CLASSES:.java=.class)
clean:
$(RM) *.class
The compilation succeeds. However, when I runjava AESCBC, I get the following error:
Exception in thread "main" java.lang.NoClassDefFoundError: org/bouncycastle/jce/provider/BouncyCastleProvider
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2693)
at java.lang.Class.privateGetMethodRecursive(Class.java:3040)
at java.lang.Class.getMethod0(Class.java:3010)
at java.lang.Class.getMethod(Class.java:1776)
at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526)
Caused by: java.lang.ClassNotFoundException: org.bouncycastle.jce.provider.BouncyCastleProvider
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

You need to specify your dependencies when running your class. Assuming your class is not compiled into a JAR you will run it like so:
java -cp [PLACE YOUR DEPENDENCIES HERE] AESCBC

error executing java class file

I have the following file ~/workspace/A/A.java:
package A;
public class A{
public static void main(String[]args){
System.out.println("Hello world");
}
}
compiling with ecj don't give me problems,but then I get this error when tring to execute:
~/workspace/A $ java A
Exception in thread "main" java.lang.NoClassDefFoundError: A (wrong name: A/A)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
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$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
~/workspace/A $ java -cp . A
Exception in thread "main" java.lang.NoClassDefFoundError: A (wrong name: A/A)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
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$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
I tried this on Linux Mint 17 with openjdk-7-jre version 7u55-2.4.7-1ubuntu1

As you said you have the structure /workspace/A/A.java
just open the terminal and browse to workspace directory then type the following command
For compiling
javac A/A.java
For executing
java A.A

did you try compiling your class first and then executing it
javac A.java
java A

1st you have to compile java program, using below command.
javac A.java
Then, run java A

First you need to compile using javac A.java
then you also need to specify classpath while running like
java -classpath . A

Don't know if ecj differs from javac, so make sure the A.class file has ended up in same dir as your java file (~/workspace/A/) after compiling and try this:
cd ~/workspace
java -cp . A.A

I recommend using a JAVA package name in lowercase especially when your classname is same as the package name. You might want to read this:
http://docs.oracle.com/javase/tutorial/java/package/namingpkgs.html

Why is my jar not running?

I can run my program outside of a jar file, but I want to deploy it and run it as a jar.
This command works for running the .class file:
java -classpath .;./libs/mail.jar;./libs/jcommon-1.0.16.jar;./libs/jfreechart-1.0.13.jar;./libs/jxl.jar;./libs/ojdbc5.jar gdsreports/ReportsDriver
This is how I package my jar file:
jar -cfvm GDSReports.jar GDSReports.mf gdsreports/* util/* libs/*
My manifest looks like this:
Manifest-Version: 1.0
Main-Class: gdsreports.ReportsDriver
Created-By: Me
This is how I run my jar:
java -classpath .;./libs/mail.jar;./libs/jcommon-1.0.16.jar;./libs/jfreechart-1.0.13.jar;./libs/jxl.jar;./libs/ojdbc5.jar;./util;./gdsreports -jar GDSReports.jar
However, run I run the jar file, it fails to load all the libraries. This is what it spits out:
Error loading configuration file: config/reportConfig
Error loading configuration file: config/gdsIds
Exception in thread "main" java.lang.NoClassDefFoundError: jxl/write/WriteException
at util.ReportConfig.setupReports(ReportConfig.java:197)
at util.ReportConfig.setup(ReportConfig.java:65)
at gdsreports.ReportsDriver.main(ReportsDriver.java:36)
Caused by: java.lang.ClassNotFoundException: jxl.write.WriteException
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 3 more
This is the expected output:
Error loading configuration file: config/reportConfig
Error loading configuration file: config/gdsIds
-------------------------------------
Running TimingReport with parameters:
Filename: Reports/06-26-2012/TimingRptZL_06-26-2012.xls
Brand: ZL
Using production database: false
-------------------------------------
-------------------------------------
Exception in thread "main" java.lang.NullPointerException
at gdsreports.TimingReport.fillChartData(TimingReport.java:417)
at gdsreports.TimingReport.fillReport(TimingReport.java:238)
at gdsreports.TimingReport.run(TimingReport.java:131)
at gdsreports.ReportsDriver.main(ReportsDriver.java:40)
What am I doing wrong?

The -classpath argument (and the CLASSPATH environment variable) are ignored when you use the -jar argument.
If a jar file depends on other libraries, you have two choices:
Use the Class-Path header in your MANIFEST.MF file to call out the other jars, or
Unpack the other jars and include them in your jar.