Creating a Jar File Using Command Prompt

**hitmen** · 03-08-2009, 12:44 PM

Q1) Dear All, I have read the Java API and my classes are stored in a folder named CPE102. However, Windows XP refuse to acknowledge my command. Tell me what is wrong?
Refer to help.jpg

Q2) I have downloaded the JavaRunner file from the Java website. However, I am not sure where to pass the arguments. How am I siuppose to tell the program which file I wanna read?

In other words, where to pass the URL if I am accessing a local directory?

import java.io.IOException;
import java.net.URL;
import java.net.MalformedURLException;
import java.lang.reflect.InvocationTargetException;

/**
* Runs a jar application from any url. Usage is 'java JarRunner url [args..]'
* where url is the url of the jar file and args is optional arguments to
* be passed to the application's main method.
*/
public class JarRunner {
public static void main(String[] args) {
if (args.length < 1) {
usage();
}
URL url = null;
try {
url = new URL(args[0]);
} catch (MalformedURLException e) {
fatal("Invalid URL: " + args[0]);
}
// Create the class loader for the application jar file
JarClassLoader cl = new JarClassLoader(url);
// Get the application's main class name
String name = null;
try {
name = cl.getMainClassName();
} catch (IOException e) {
System.err.println("I/O error while loading JAR file:");
e.printStackTrace();
System.exit(1);
}
if (name == null) {
fatal("Specified jar file does not contain a 'Main-Class'" +
" manifest attribute");
}
// Get arguments for the application
String[] newArgs = new String[args.length - 1];
System.arraycopy(args, 1, newArgs, 0, newArgs.length);
// Invoke application's main class
try {
cl.invokeClass(name, newArgs);
} catch (ClassNotFoundException e) {
fatal("Class not found: " + name);
} catch (NoSuchMethodException e) {
fatal("Class does not define a 'main' method: " + name);
} catch (InvocationTargetException e) {
e.getTargetException().printStackTrace();
System.exit(1);
}
}

private static void fatal(String s) {
System.err.println(s);
System.exit(1);
}

private static void usage() {
fatal("Usage: java JarRunner url [args..]");
}
}

In short, I just want to create a jar file and then run it automatically using a click. HELP

**toadaly** · 03-08-2009, 12:52 PM

The problem is that windows doesn't know where the 'jar' executable is.

Go to your windows control panel, open up "system", click the advanced tab, and then the 'environment variables' button. Add the path to your jdk's bin directory to the 'PATH' variable, and then the command prompt will find the 'jar' command.

I don't know why the java installer doesn't set this up automatically, but it's very annoying.

**Eranga** · 03-08-2009, 05:27 PM

Originally Posted by toadaly

I don't know why the java installer doesn't set this up automatically, but it's very annoying.

I think this is happen on SDK installation, not with the JDK installation. JDK comes with jar bundle too.

**hitmen** · 03-09-2009, 03:36 AM

It still doesnt work.Look at my screenshot below
BTW what is the diff btw a classpath and a path
and what is the difference btw a JDK and SDK? I thought they are the same

And is there a way to create a JAR file without using command prompt?

**Eranga** · 03-09-2009, 10:26 AM