I want to create our own jar which has some simple methods like a print method.
I created the jar of that java project and imported it into an other project I am building path also.
The problem is that I am able to create the object of the classes which reside in the jar but I am unable to call the methods of that class.
i am using eclipse 3.4 (Eclipse Ganymede (3.4))version
Sounds like if you are successfully building the JAR that you are not including it in the classpath when you compile / run your application. You can do that if you are compiling/running from the command line with the -cp or -classpath option. Both perform the same function.
To compile:
javac -cp .:PathToMyJar/MyJar.jar MyMainClass.java
To Run:
java -cp .:PathToMyJar/MyJar.jar MyMainClass
The above commands will look in the current directory ('.') and in the MyJar.jar file specified. On Windows you will separate the items in the classpath with a semicolon and on Linux/Unix/OS X you will use a colon.
If you are using an IDE you will need to somehow add the JAR file to the classpath for your project. How to do that is IDE specific.
Related
I have compiled my java code using eclipse but not it has to be deployed and a cron job has to execute it. I am trying to execute it from command line in Windows, but getting Could not find or load main class. I tried setting classpath using java -cp bin\com\pega\download\engineclasses but it still throws the same error. My folder structure looks like below
C:\Users\s2517457\G360_Linux\FiddlingPega
|__\bin\com\pega\download\engineclasses\TestUtils.class
|__\src\com\pega\download\engineclasses\TestUtils.java
Please let me know what should be the javac and java commands for this to work.
You should use the following command:
java -cp bin/ com.pega.download.engineclasses.TestUtils
Your are telling to java that the entire bin folder is your classpath and the main class is in the class com.pega.download.engineclasses.TestUtils
If you want to add jars as well, you must call the command like:
java --classpath "bin/;lib/*" com.pega.download.engineclasses.TestUtils
Where lib is the folder containing the Jars files
So, I have exported my project in both Netbeans and Eclipse and when I try to
java -jar myproject.jar
I get this prompt
In my project I have some libraries which are located inside of src in Netbeans and out of src in Eclipse as it should (please correct me if I'm wrong) The libraries are included via:
Java Build Path > Add JARs...
I've done some research and it seems that I have to change my JAVA CLASSPATH or somethng like that but I don't know exactly how to do it.
The project works perfectly when I compile it and run it, but it crashes after I build it into a Jar file.
By the way, if it isn't clear enough I'm on Ubuntu 14.04
You need to create the path for the jar files and pass it on the command line.
Something like this:
ftp_jar=${Utils_home}/bin/ftpClientUtil.jar
net_jar=${Utils_home}/bin/commons-net-3.3.jar
jsch_jar=${Utils_home}/bin/jsch-0.1.51.jar
java -cp .:$jsch_jar:$net_jar:$ftp_jar com.myplace.ftputils.SFTPClientUtil $*
Run your program as:
java -cp .:[path-of-lib1.jar]:[path-of-lib2.jar] -jar myproject.jar
replace [path-of-libX.jar] with actual path of your libraries.
I'm trying to make a jar file out of two classes, one of which depends on an external jar. I have a directory with a manifest.txt, a lib folder containing the external jar RXTXcomm.jar, and a folder named Arduino containing my two classes, SendValue.java and SerialClass.java.
First I'm compiling my classes using:
javac arduino\*.java
This creates 3 new files, SerialClass$1.class, SerialClass.class and SendValue.class. To make the jar file, I'm running:
jar -cfm send.jar manifest.txt arduino\*.class lib\rxtxcomm.jar
This works fine. I then try to run the file using:
java send.jar
I get the error:
Could not find or load main class send.jar
I've also tried to run it with the following command, and got the same error:
java -cp . send.jar
The only line in my manifest.txt is :
Main-Class: Arduino.SendValue
My classes run fine in Eclipse, so I'm assuming they're not the problem. SendValue.java has the line:
public static void main(String[] ag) {
as it's supposed to.
Any ideas?
You want to run your jar using:
java -jar send.jar
Also, unless you want to do some magic with nested jars with some tool like OneJar, you should remove lib\rxtxcomm.jar from your jar command, and add the following line to your manifest.
Class-Path: lib\rxtxcomm.jar .
If you're going to use the command line or terminal for running a single java executable, then use
java -jar send.jar
Also it would be better if you went through compiling and testing using an IDE such as Netbeans, IntelliJ IDEA, or Eclipse as they're meant to do such stuff and are more reliable on doing the steps unlike the human brain.
I have exported a jar file that I want to run the console. The code compiles and runs correctly in eclipse but I am having an issue running it from the console.
To me it looks like the referenced jar's I added via built path in the Eclipse project file and not being added to the export. If that is the case, how do I ensure that they do? If not, what am I doing wrong?
When you export your source code's class files to a jar using eclipse, only the .class files of your source are exported! Hence your exported jar file doesn't contain the referenced jars you mentioned in eclipse! Due to this, the error occurs while executing from command prompt.
Solution:
Take all the jar files required to execute the program, store it in the same directory as you store the exported jar file. Now while executing the java command, provide all the jar file's names in classpath field as following:
java -classpath .;JAR1.jar;JAR2.jar MainClass
Once you do this, your problem should be resolved!
The dependencies need to be on the classpath, i.e. run like this:
java -cp <path_to_jar1>;<path_to_jar2> -jar ScrumTimeCaptureMaintenence.jar
When running from the command line make sure any dependencies are set on the class path by listing them in the -classpath parameter
I've looked through many of the existing threads about this error, but still no luck. I'm not even trying to package a jar or use any third-party packaging tools. I'm simply running from within Eclipse (works great) and then trying to run the exact same app from the command line, in the same location it's built to (getting this error). My goal is to be able to zip up the bin folder and send it off to be run by someone else via a command line script. Some details:
It's a command-line app and I'm using the commons-lang-2.4.jar for string utilities. That is the file that cannot be located (specificaly "java.lang.NoClassDefFoundError: org/apache/commons/lang/StringEscapeUtils")
I have that jar in my lib folder and have added it to my build path in Eclipse via right-click "Build Path -> Add to Build Path"
The .classpath file looks correct and contains the reference to the jar, but I assume that file is only used by Eclipse (contains this line: <classpathentry kind="lib" path="lib/commons-lang-2.4.jar"/>)
Could this be related to the Eclipse working directory setting? I have some internal template files that I created that are under src/templates, and the only way I can seem to get those to be seen is by setting the project working directory to AppName/src. Maybe I should be putting those somewhere else?
Let me know if any additional info would help. Surely this is something simple, but I've wasted too much time on it at this point. This is reminding me why I originally left Java back in '05 or so...
A NoClassDefFoundError basically means that the class was there in the classpath during compiletime, but it is missing in the classpath during runtime.
In your case, when executing using java.exe from commandline, you need to specify the classpath in the -cp or -classpath argument. Or if it is a JAR file, then you need to specify it in the class-path entry of its MANIFEST.MF file.
The value of the argument/entry can be either absolute or relative file system paths to a folder containing all .class files or to an individual .jar file. You can separate paths using a semicolon ;. When a path contains spaces, you need to wrap the particular path with doublequotes ". Example:
java -cp .;c:/path/to/file.jar;"c:/spacy path/to/classes" mypackage.MyClass
To save the effort of typing and editing the argument in commandline everytime, use a .bat file.
Edit: I should have realized that you're using an Unix based operating system. The above examples are Windows-targeted. In the case of Unix like platforms you can follow the same rules, but you need to separate the paths using a colon : and instead of an eventual batch file, use a .sh file.
java -cp .:/path/to/file.jar:"/spacy path/to/classes" mypackage.MyClass
Are you specifying the classpath to java on the command line?
$ java -cp lib/commons-lang-2.4.jar your.main.Class
The classpath setting you are setting in Eclispe are only for the IDE and do not affect how you application is run outside the IDE. Even if you use the Eclipse Functionality to export your application as an executable jar file there is no out of the box way to package all the jars your application depends on.
If you have packaged you application into a jar file called myapp.jar then running a command like below will run the application with the jar you depend on, if you have more than one just add them separted by ; on Windows or : on Unix:
java -jar myapp.jar -cp .;c:/pathtolibs/commons-lang-2.4.jar
If you are just running the classes directly then either run the folder containing your .class files will also need to be on the path (though I assume it already is since you are able to run the program and get errors).
Consider File -> Export -> Runnable jar to create a jar file which can be invoked directly with
java -jar yourProgram.jar
There are several variants depending on your needs.
Eclipse does not move any of the jars in your classpath into the bin folder of your project. You need to copy the util jar into the bin folder. If you move it to the root of the bin folder, you might be able to get away without any classpath entries but it's not the recommended solution. See #BalusC's answer for good coverage of that.
Eclipse doesn't build executable java classes by default. Don't ask me why, but it probably has something to do with using their own tools.jar (somewhere in plugins/org.eclipse.core ?) so that Eclipse can run without a JDK.
You can usually go to your project bin directory and do:
java -cp . MyClass
But if you have external jars, Eclipse handles those internally in another weird way, so you'll need to add those too.
make sure your jar commons-lang-2.4.jar in classpath and not redudance.
I ever add jar file to my classpath, and have 2 file jar in my classpath. After I delete it, work smooth