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Eric Walton
Eric Walton

Reputation: 27

jar file execution from cmd prompt

I thoroughly checked this one, and the standard answers aren't working for me.

Whenever I try to execute a jar file from cmd prompt, instead of opening the jar file it opens a new window of Dr. Java.

I've used DrJava's "Create custom drjava jar" to create a jar file called "TestJar.jar", including:

Manifest.txt:

Main-Class: com.package.name.TestJar Class-Path: algs4.jar

TestJar.java:

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

}

I type this in the cmd prompt:

java -jar TestJar.jar

And DrJava opens a new window. Any ideas? I've tried creating the jar file from cmd prompt but all commands I type starting with "jar" get this error:

'jar' is not recognized as an internal or external command, operable program or batch file.

Any help would be greatly appreciated...I'm pretty new to Java.

Upvotes: 1

Views: 6198

Answers (3)

paulsm4
paulsm4

Reputation: 121881

1) To run your test jar from a Windows command:

a) Make sure Java is installed on your PC

b) Set your %JAVA_HOME% (EX: set JAVA_HOME=c:\Program files\java\jre7)

c) Update your %PATH% (EX: PATH=c:\Program files\java\jre7\bin;%PATH%)

d) Invoke program with "java -jar JARFILE MAIN-CLASS (EX: java -jar TestJar.jar TestJar)

2) To run DrJava .jar on Windows, I would just double-click on the .jar file from Windows Explorer

3) To test and debug your program, I would just use DrJava (instead of from the command line).

4) You do NOT need "jar.exe" installed to run a .jar file. You only need it to view, modify or create a .jar. jar.exe comes with the Java JDK.

5) I suspect you probably WILL need the Java JDK to build or debug any programs with DrJava, however.

Here's a good link on running .jar files from Windows, if you need more help:

Upvotes: 0

jpmc26
jpmc26

Reputation: 29974

Java determines the location of the main function using a manifest. If you unzip your jar file, you'll see the manifest file in a META-INF folder. (A jar file is just a zip file with a different extension and some specific files inside.)

You'll need an entry like this in your manifest:

Main-Class: packagename.classname

See here for more details about setting the location of main.

To control the manifest in Dr. Java, I think you will need to create a custom manifest. This source provides these instructions:

For more control over the properties of the jar, you may enter a custom manifest by selecting "Custom Manifest" and pressing the "Edit Manifest" button.

Upvotes: 0

sigpwned
sigpwned

Reputation: 7463

The problem you're having is that the jar program is not in your %PATH%. You may find this answer helpful.

Upvotes: 1

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