How to Set Classpath in Linux to Let Java Find Jar File

How to set CLASSPATH in Linux to let java find jar file?

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.

set java classpath to multiple folders that have jar files and run from command line

Here is the solution that finally worked as expected. When the '*' character is used in the classpath for my specific scenario, it skipped everything after the first path. Using the double quotes(") for each path separately and then using ";" as the delimiter is the solution.

Having any space before or after the semi-colon ";" will also not work

javac -verbose -classpath "C:\Program Files\lib\java\core\*";"C:\Program Files\lib\java\core\locale\*";"C:\Program Files\lib\java\modules\*";"C:\Program Files\lib\java\modules\ext\*" testClass.java

How to get the path of a running JAR file?

return new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation()
    .toURI()).getPath();

Replace "MyClass" with the name of your class.

Obviously, this will do odd things if your class was loaded from a non-file location.

Determine which JAR file a class is from

Yes. It works for all classes except classes loaded by bootstrap classloader. The other way to determine is:

Class klass = String.class;
URL location = klass.getResource('/' + klass.getName().replace('.', '/') + ".class");

As notnoop pointed out klass.getResource() method returns the location of the class file itself. For example:

jar:file:/jdk/jre/lib/rt.jar!/java/lang/String.class
file:/projects/classes/pkg/MyClass$1.class

The getProtectionDomain().getCodeSource().getLocation() method returns the location of the jar file or CLASSPATH

file:/Users/home/java/libs/ejb3-persistence-1.0.2.GA.jar
file:/projects/classes

Spring Boot Executable Jar with Classpath

If you just want add external libraries you can use the loader.path property.

java -Dloader.path="your-lib/" -jar your-app.jar

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UPDATE

If you also need to read additional files from the classpath you have to create/change the manifest file of your application.

Lets assume that your are initializing your Spring Boot context from the class de.app.Application. Your MANIFEST.MF should looks as follows:

Manifest-Version: 1.0
Main-Class: de.app.Application
Class-Path: your-lib/

And the you can simply start your app with java -Dloader.path="your-lib/" -jar MyApp.jar.

For more information about the MANIFEST.MF please see Working with Manifest Files: The Basics.

Java Classpath not using current directory

Relying on the CLASSPATH system variable is a bad idea. One machine can be used to run many varied apps, so the concept of a 'global setting' is silly.

Try java -cp . Main.

If that DOES work

Then you've been messing with your CLASSPATH environment var and removed . from it. Put it back. Or better yet forget about CLASSPATH; always use -cp; use -cp . if you like. Or make jar files and run them with java -jar thejar.jar, which ignores both CLASSPATH and the -cp parameter (instead that will look at the Class-Path entry in the jar manifest).

If that does not work

Then you were not in the appropriate directory. Or, you're confused about packages. Let's say your Main.java looks like this:

package com.foo;

public class Main {
  public static void main(String[] args) {
    System.out.println("Hello");
  }
}

And you compile it; a Main.class file shows up.

java cannot run this unless Main.class is in a directory named foo, and that directory is in turn in a directory named com. Then, you put the directory that contains com on the classpath. Not the directory that contains Main.class. And then you run java -cp theDirThatContainsCom com.foo.Main. It is not possible to run this file with java -(does not matter what you try it cannot be done) Main - because you provide the full name of the class you want to run to java, and the full name is com.foo.Main.

Execute jar file with multiple classpath libraries from command prompt

Let maven generate a batch file to start your application. This is the simplest way to this.

You can use the appassembler-maven-plugin for such purposes.

how to set class path for more than one jar is used in command prompt in java

For multiple jars you can do

java -cp "path1/servlet.jar;path2/mysql.jar" yourPackage.Class

Or put all jars in one folder (let it be path1/lib) and do something like following

java -cp "path1/lib/*" yourPackage.Class

Note : classpath wildcards can be used only in Java 6 or later.

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