Luckily or unluckily, I haven't had to work too extensively with invoking java from the commandline up until this point, I've usually been using something like Maven, Ant, or running things within a servlet container. I've just compiled my application in Maven into one JAR using the assembly:single goal, and am having serious problems running it from the commandline.
Here's what I'm attempting to do:
export JAVA_CLASSPATH="`pwd`:/path/to/remote/libs/"
java -cp "${JAVA_CLASSPATH}" -jar groupId-artifactId-version-jar-with-dependencies.jar com.my.main.Class
This is failing with the following error:
Exception in thread "main" java.lang.NoClassDefFoundError: com/remote/lib/IServer
Caused by: java.lang.ClassNotFoundException: com.remote.lib.IServer
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: com.my.main.Class. Program will exit.
The IServer class is in the /path/to/remote/libs directory and isn't being found. It also seems to not be able to find the main class, which is really odd. What am I doing wrong?
The -jar option ignores the classpath ( and all other ) options.
You need to edit the manifest file in your jar and set the Class-path variable in there.
http://download.oracle.com/javase/1.4.2/docs/tooldocs/linux/java.html
#Kal's answer is correct, but an easier way to fix it would be this:
export JAVA_CLASSPATH="groupId-artifactId-version-jar-with-depencies.jar:`pwd`:/path/to/remote/libs/iserver.jar"
java -cp "${JAVA_CLASSPATH}" com.my.main.Class
No need to tinker with the manifest file; just add the jar you want to the classpath.
Also, if the IServer stuff is in a jar inside /path/to/remove/libs/ then you need to explicitly include the name of the jar file. I've included it above and assumed it is called "iserver.jar"
If you have many dependencies then it's often easier to write a shell script for launching your code. The script can build a (potentially very large) classpath string using shell glob goodness. The java executable doesn't do any globbing.
EDIT: Note that I've assumed that you don't have access to Ant or Maven or any of that good stuff, since you stated that you usually use those tools but are not doing it right now.
The classpath parameter must be specified with the exact path to the jar file. If your IServer class is found in server.jar, you need to specify "$pwd\:/path/to/remote/libs/server.jar", for example. (in other words, you need to include a :-separated list of paths to jar files)
As others have noted, if you choose this method you should remove the -jar parameter and instead include the class name you intend to be your main class on the command line, such as java -cp $PWD:/path/to/server.jar com.remote.lib.IServer.
Side note: usually names that start with I are reserved for interfaces; it seems a bit odd to use an interface as your main class.
Related
I try to create a Minecraft Plugin (it's my first one) and I can't fix this error:
So, the plugin compiles good but when the code has to execute this code :
BCrypt.checkpw(mdp, result.getString("mdp"))
that come from the lib org.mindrot.BCrypt, I have this error :
Caused by: java.lang.NoClassDefFoundError: org/mindrot/BCrypt
But, when I open my JAR with WinRAR, there is my lib bcrypt (so it's well export). And it's also in my .classpath.
Can you help me ?
Thanks.
There are several ways to configure the CLASSPATH when launching a java application via the java command. According to what you posted so far, I would use the -classpath flag:
java -classpath spigot.jar;jbcrypt.jar class.containing.main.method.MyMain
Alternatively, you could modify the MANIFEST in file spigot.jar. Refer to Adding Classes to the JAR File's Classpath.
Or you could copy jbcrypt.jar to the directory pointed to by the java System property "java.ext.dirs".
I am getting a classnotfound exception. The class which is claimed to be not found does not exist, but the class name is set as the path to the list of input files for my map reduce jobs.
INFO server Running: /usr/lib/hadoop/bin/hadoop --config /var/run/cloudera-scm-agent/process/155-hue/JOBSUBD/hadoop-conf jar tmp.jar /user/hduser/datasets/ /user/hduser/tmp/job_20/ mongodb://slave15/db_8.job_20
Exception in thread "main" java.lang.ClassNotFoundException: /user/hduser/datasets/
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at org.apache.hadoop.util.RunJar.main(Runjar.java:190)
As we can see, the /user/hduser/datasets/ is the path to the input files. Why am I getting this error as ClassNotFoundException? Why does it see it as a class?
I found my own error. I have a package structure. I need to specify my package information
/usr/lib/hadoop/bin/hadoop
--config /var/run/cloudera-scm-agent/process/155-hue/JOBSUBD/hadoop-conf
jar tmp.jar org.myorg.tmp /user/hduser/datasets/
/user/hduser/tmp/job_20/ mongodb://slave15/db_8.job_20
In my tool, there is no option for giving the package as argument to Java. So I need to have no packaging. But then I am having the following error since the argument before this input file path is missing.
My classes are directly in the tmp.jar in its root. I mean no org.myorg etc...
SOLUTION:
jar cmf [manifest_file] [jar_name.jar] -C [folder_of_classes] [path_for_jar_file]
it will merge the content of the manifest_file with the generated manifest file in the jar archive. Include the following line in the manifest_file
Main-Class: [Name_Of_Class]
Whether or not there's a package hierarchy (and if there isn't, you've done Something Wrong) you still need to give it the name of the class containing main.
For example, the docs have an example where the main class is org.myorg.WordCount. Even if WordCount was in the default package, it should be specified if the jar file doesn't include a main class in the manifest:
bin/hadoop jar /usr/joe/wordcount.jar WordCount /usr/joe/wordcount/input /usr/joe/wordcount/output
I'd assume you could also specify the main class in the manifest as with any jar; the class argument is shown as optional in those same docs.
I am trying to run a file from command line. The file is a .class file and is apart of a larger project that I compiled in Netbeans. I navigated to the .class file and ran
java MyFile
And I got:
Exception in thread "main" java.lang.NoClassDefFoundError: PersonTest/class
Caused by: java.lang.ClassNotFoundException: PersonTest.class
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: PersonTest.class. Program will exit
Whats up with that? (I should mention that i'm running ubuntu)
You need to check this useful link java - the Java application launcher:
By default, the first non-option
argument is the name of the class to
be invoked. A fully-qualified class
name should be used
So, you have to write the full qualified name of the class (this includes the package name).
So, the right way to execute your command is this (from the root dir where your class files are stored):
> java my.package.MyFile
Also, make sure to include all the needed dependencies at the classpath (-cp) argument (check the referenced link).
UPDATE: to include a classpath setting example:
java -classpath C:\MyProject\classes;C:\MyProject\lib\utility.jar my.package.MyFile
With this, the java runtime will search for the classes at the C:\MyProject\classes directory, and at the C:\MyProject\lib\utility.jar JAR file. You'll need not only your class direct dependencies, but the dependencies needed by the referenced files (the whole tree).
The answer appears to be in this line:
Exception in thread "main" java.lang.NoClassDefFoundError: PersonTest/class
It means you didn't type:
java MyFile
as you said in your original post, you typed
java PersonTest.class
you should have typed
java PersonTest
Yes you can, they are compiled by a java compiler. If you have the right version of the jvm (often other versions work aswell) than it can be run. The information about your error is not enough to tell what went wrong.
Your probably in the wrong folder, mistyped the classname, used a class in your code that couldn't be found, etc.
Unless your class is entirely standalone (i.e. only references java.lang classes like String), you'll need to add other classes/JARs to the classpath when you invoke Java.
The NoClassDefFoundError (which usually states the name of the class by the way, and always includes a stacktrace) indicates that an external class that was available when your class was compiled, is not available on the classpath at runtime.
EDIT based on update:
You're invoking your process incorrectly. You don't need to append the .class suffix of the file - doing so makes Java look for a file class class in a subpackage.
(P.S. you said you ran java MyFile. That's a lie, you actually ran java PersonTest.class. If you'd noted that to start with, it would have made it much easier for people to answer the question!)
Just consider this example
say I already have a folder src and I wrote in my notepad
package test.oye;
class testclass {
static public void main (String [] args)
{
int a=3;
System.out.println(a);
}
}
then what go to src folder and you ,yourself create a folder named test and inside it oye . Then put your .java file in it . Then cd src/test/oye only(in Command prompt or terminal).From there itself
javac testclass.java
cd src
java test.oye.testclass
This will work for sure.
If you don’t want to put .java file there … then just compile your .java file and get the .class file .
Now create the test folder and then oye inside it ….and put .class file inside it ….
Now go back to src …and then type
java test.oye.testclass;
according to terminal ide, android requires classes in DEX format when running them.
Try:
dx --dex --output=practice.jar practice.class
Then run using this:
java -jar practice.jar practice
I'm trying to run .class file from command line. It works when I manually move to the directory it's stored in, but when I try something like this:
java C:\Peter\Michael\Lazarus\Main
it says it can't find the main class. Is there any solution to this other than making a .jar file (I know that .jar is the best solution, but at this moment isn't the one I'm looking for)?
The Java application launcher (a.k.a java.exe or simply java) supports up to four different ways to specify what to launch (depending on which Java version you use).
Specifying a class name is the most basic way. Note that the class name is different from the file name.
java -cp path/to/classFiles/ mypackage.Main
Here we start the class mypackage.Main and use the -cp switch to specify the classpath which is used to find the class (the full path to the class mypackage.Main will be path/to/classFiles/mypackage/Main.class.
Starting a jar file.
java -jar myJar.jar
This puts the jar itself and anything specified on its Class-Path entry on the class path and starts the class indicated via the Main-Class entry. Note that in this case you can not specify any additional class path entries (they will be silently ignored).
Java 9 introduced modules and with that it introduce a way to launch a specific module in a way similar to how option #2 works (either by starting that modules dedicated main class or by starting a user-specified class within that module):
java --module my.module
Java 11 introduces support for Single-File Source Code Programs, which makes it very easy to execute Java programs that fit into a single source file. It even does the compile step for you:
java MyMain.java
This option can be useful for experimenting with Java for the first time, but quickly reaches its limits as it will not allow you to access classes that are defined in another source file (unless you compile them separately and put them on the classpath, which defeats the ease of use of this method and means you should probably switch back to option #1 in that case).
This feature was developed as JEP 330 and is still sometimes referred to as such.
For your specific case you'd use option #1 and tell java where to look for that class by using the -classpath option (or its short form -cp):
java -classpath C:\Peter\Michael\Lazarus\ Main
If your Main.java contains the entirety of your source code (and it is in the same directory), then you can use option #4, skip the compile step and directly compile-and-execute it:
java c:\Peter\Michael\Lazarus\Main.java
Assuming that Main.class does not have a package declaration:
java -cp C:\Peter\Michael\Lazarus\ Main
Java looks for classes in a "classpath", which can be set on the command line via the -cp option.
I just had the same issue, I tried running java hello.class, this is wrong.
The command should be java hello.
Do not include the file extension. It is looking for a class file, and will add the name on its own.
So running 'java hello.class' will tell it to go looking for 'hello.class.class' file.
Try this:
java -cp C:\Peter\Michael\Lazarus Main
You need to define the classpath.
I'd like to make "double-click" cli application but still don't get how.
I know I should propably somehow edit manifest but that is all. I googled ofc. but no success.
Thanks for any tips.
Here is the output from build, run, and manifest:
compile:
Created dir: /home/nick/NetBeansProjects/SemestralWork/dist
Building jar: /home/nick/NetBeansProjects/SemestralWork/dist/SemestralWork.jar
Not copying the libraries.
To run this application from the command line without Ant, try:
java -jar "/home/nick/NetBeansProjects/SemestralWork/dist/SemestralWork.jar"
jar:
BUILD SUCCESSFUL (total time: 1 second)
java -jar /home/nick/NetBeansProjects/SemestralWork/dist/SemestralWork.jar
Exception in thread "main" java.lang.NoClassDefFoundError: semestralwork/Main
Caused by: java.lang.ClassNotFoundException: semestralwork.Main
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:319)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:264)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:332)
Could not find the main class: semestralwork.Main. Program will exit.
MY MANIFEST created with build:
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.7.1
Created-By: 14.0-b08 (Sun Microsystems Inc.)
Main-Class: semestralwork.Main
Class-Path:
X-COMMENT: Main-Class will be added automatically by build
These two lines tell you all you need to know:
Exception in thread "main" java.lang.NoClassDefFoundError: semestralwork/Main
Caused by: java.lang.ClassNotFoundException: semestralwork.Main
And a further clue is dropped by the manifest output:
Main-Class: semestralwork.Main
This means that the JAR file is looking for a package named semestralwork and a class named Main inside it. It fails at this point because it cannot find either the semestralwork package or the Main class.
As you pointed out in your question, the problem is indeed in the manifest file. You can edit this directly in your JAR file if you like, but a better idea would be to do this from Netbeans:
Click on `File --> Project Properties (semestralwork)'
In the dialog that opens, on the tree on the left select Run
Then, on the right, under the field labeled Main class:, enter the fully qualified class name of the class that you want executed when run from the command line.
In your case, as I see from your comment on #Aaron's answer, if your main class is in a file called encryption.java, and it is in the default package (no package), just enter encryption.
Once this is done, do a clean and build, then try running it from the command line again.
HTH
Since I encountered the same problem, I can clarify the solution a little bit.
You must create main Java class outside your method (for example-default_package folder), and then invoke your method(folder), e.g import your_folder.connected_class; in that main class.
Hopefully I could help someone with the same problem.
It's easier to make a .exe from a .jar without netbeans.
Here are my suggestions:
1. Use a special application for this(ex: JSmooth, JEXECreator etc)
2. Make a C++ program that starts a JVM (see this tutorial)
The default class search path may be the issue. You should try changing directory to the location the jar is and launching with java -jar Semestral.jar. Also you may have misnamed the main class. Please also include your package structure.
Open the JAR file with a ZIP tool (or try less ... if you're on Linux or jar tvf ...). Make sure there is a directory semestralwork in there which contains a file Main.class.
It's Easy. Download a copy of netbeans. Make a new project in netbeans. Goto your main class in the Projects Explorer. This should be folder "YourProject" As the class YOURPROJECT.JAVA . It is this yourproject.java file that you want to start with. Just write your code into the public static void main area. You can run the program with the green play button in the top toolbar.