If I extract a Jar file into a directory, what's the correct java command to run it as if it was the jar?
Meaning, what would be the equivalent command to java -jar myProgram.jar except not using the jar itself?
I've tried stuff like java -cp ".;META-INF\lib\*" JarMain but it seems like there's still something missing there.
Do you mean that add a jar to classpath but do not run it? If so, java -cp myProgram.jar;ohterjar/libdir JarMain. If you use linux/mac,replace ; to :.
If you run jar file directly (without extracting), you can use command: java -jar jarfilename. jar
If you extract jar file into separated files, you can run .class file only. Use the command java classfilename.
You need to set path environment to java/bin directory before running above commands, or just change directory to it.
Related
I've compiled a JAR file and specified the Main-Class in the manifest (I used the Eclipse Export function). My dependencies are all in a directory labeled lib. I can't seem to get a straight answer on how to execute my JAR file while specifying it should use the lib/* as the classpath.
I've tried:
]$ java -jar -cp .:lib/* MyJar.jar
]$ java -cp .:lib/* -jar MyJar.jar
]$ java -cp .:lib/* com.somepackage.subpackage.Main
etc...
Each gives an error saying:
Error: Could not find or load main class ....
or gives the NoClassDefFoundError indicating the libraries are not being found.
I even tried remaking the JAR file and included the lib directory and contents, but still no dice...
How can I execute a JAR file from the command line and specify the classpath to use?
When you specify -jar then the -cp parameter will be ignored.
From the documentation:
When you use this option, the JAR file is the source of all user classes, and other user class path settings are ignored.
You also cannot "include" needed jar files into another jar file (you would need to extract their contents and put the .class files into your jar file)
You have two options:
include all jar files from the lib directory into the manifest (you can use relative paths there)
Specify everything (including your jar) on the commandline using -cp:
java -cp MyJar.jar:lib/* com.somepackage.subpackage.Main
Run a jar file and specify a class path like this:
java -cp <jar_name.jar:libs/*> com.test.App
jar_name.jar is the full name of the JAR you want to execute
libs/* is a path to your dependency JARs
com.test.App is the fully qualified name of the class from the JAR that has the main(String[]) method
The jar and dependent jar should have execute permissions.
You can do these in unix shell:
java -cp MyJar.jar:lib/* com.somepackage.subpackage.Main
You can do these in windows powershell:
java -cp "MyJar.jar;lib\*" com.somepackage.subpackage.Main
Alternatively, use the manifest to specify the class-path and main-class if you like, so then you don't need to use -cp or specify the main class. In your case it would contain lines like this:
Main-Class: com.test.App
Class-Path: lib/one.jar lib/two.jar
Unfortunately you need to spell out each jar in the manifest (not a biggie as you only do once, and you can use a script to build the file or use a build tool like ANT or Maven or Gradle). And the reference has to be a relative or absolute directory to where you run the java -jar MyJar.jar.
Then execute it with
java -jar MyJar.jar
You can do a Runtime.getRuntime.exec(command) to relaunch the jar including classpath with args.
Under Linux I am trying to run a jar file as follows:
java -jar plantuml.jar -testdot
while having CLASSPATH set to any of the following (the file is located at /home/user/plantuml.jar):
export CLASSPATH=/home/user
export CLASSPATH=/home/user/
export CLASSPATH=/home/user/plantuml.jar
In either case, no matter how I define CLASSPATH, the java command gives an error Unable to access jarfile plantuml.jar. What am I doing wrong here?
You have to supply the complete path after the parameter -jar. So for your example you have to call
java -jar /home/user/plantuml.jar -testdot
The $CLASSPATH is only evaluated to find additional files (classes/resources) but not the jar file defined in the command line.
export CLASSPATH="/path/to/class_or_jar1":"/path/to/class_or_jar2":"${CLASSPATH}"
Maybe you are missing name of the main class or path to the jar. Have you tried execute it:
java -jar full_path/plantuml.jar package.YourClass -testdot
Is your program depending on other classes? If yes you might want to add -cp parameter.
The classpath is used to find classes when you refer to them by name. It's essentially a list of paths (directories AND jar/zip files) where the JVM needs to look for classes, or other resources when using methods like ClassLoader.getResourceAsStream().
The value passed to the -jar option on the command line is the file-path to the JAR file.
So, it won't find a jar file if you are only referring to the jar file by name. The JAR file path in the CLASSPATH is supposed to be a path element that 'contains' other resources.
What you need to do here, is either
Provide the full path to the jar file when trying to execute the jar
Set the classpath to the jar file's path, and run the java command giving the name of the main class you want to execute.
How can I run a jar that needs several jars to work?
Let me explain, I have for example a project with a jar "Main.jar" but to run this Main.jar I need jdom.jar(for xml file), jGit.jar...
Assume we need more than two jars. How can I run my Main.jar?
By including the needed jar files in the classpath. Something like:
java -cp "Main.jar;jdom.jar;jdom.jar" MainClass
If you are under Windows and would like to execute the Main.jar with a double click, you will need to create a .bat file and use that one instead to run your program. The content of the .bat file will have the above command.
Under Unix/Linux you will create a shell file with the similar content.
Note that the -cp argument values will need to contain all the jars that your Main.jar is depended on.
Run the jar with main class and add all other jars to classpath.
java -cp yourJars yourClass
see this post for more info. See this java tutorial
There was a program that I used that made runnable .jar files.. All the ones I'm finding now are ones that make .exe files.. I remember it also has the option to make the file a .sh script as well. Anyone knows its name? I've been searching for hours with no avail :/
The command line
java -jar file.jar
Will run your jar file if it has a Main-Class defined as explained here.
You can use that command in a shell script.
You can create a runnable jar using NetBeans IDE or Eclipse IDE by just providing the main class to run. Rest of the things it will take automatically. That class must be having a main() method in it. Then you can run that jar file using java -jar yourjarfile.jar
Do you mean actually coding java and then compiling to .jar? If you do try
eclipse code editor
I used eclipse to make minecraft mods. It will work if you want to make .jar programs.
If you want to have a jar that you can execute using the usual syntax ./app.jar (instead of java -jar), here is a post explaining the process: how to create executable jars.
Basically, JAR is a variant of ZIP, which allows random bytes to be pre/appended to the JAR without corrrupting it. This means it is possible to prepend a launcher script at the beginning of the jar to make it "executable".
Here is a simple example of the process:
# Append a basic launcher script to the jar
cat \
<(echo '#!/bin/sh')\
<(echo 'exec java -jar $0 "$#"')\
<(echo 'exit 0')\
original.jar > executable.jar
# Make the new jar executable
chmod +x executable.jar
With this, you can now run ./executable.jar instead of java -jar original.jar. This works on all unix like systems including Linux, MacOS, Cygwin, and Windows Linux subsystem.
I create .jar file in eclipse. I use .jar file to print text on pos printer. My program is printing correctly, but when I start .jar file is not connecting with the printer. For connecting with the printer I use javax.comm library.
Open up the jar in achiever tool edit Menifest.txt add the following
Class-Path: /path/to/requiredLibary.jar
Also See
Adding Classes to the JAR File's Classpath
Is the javax.comm jar in the classpath when you start the jar from the command line?
Something like:
java -cp myproject.jar;javax-comm-3.0.jar com.mycompany.MyMainClass
Note that the java -jar myproject.jar is incompatible with -cp, ie this doesn't work: java -cp javax-comm-3.0.jar -jar myproject.jar