Executable jar file

[franklyn@bellsouth.net]

Can the main class be included in a package? And can this package be created into a jar executable?

I was able to create a package with no compile error. I was also able to create a jar file from the *.class files in the package. The jar file is in the CLASSPATH environment variable. But got the following errors when trying to execute the jar file:

java -jar test.jar
Exception in thread "main" java.lang.NoClassDefFoundError: PackageTest
Caused by: java.lang.ClassNotFoundException: PackageTest
at java.net.URLClassLoader$1.run(URLClassLoader.java: 202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 07)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 48)
Could not find the main class: PackageTest. Program will exit.

Thx

[JosAH]

Can the main class be included in a package? And can this package be created into a jar executable?

I was able to create a package with no compile error. I was also able to create a jar file from the *.class files in the package. The jar file is in the CLASSPATH environment variable. But got the following errors when trying to execute the jar file:

java -jar test.jar
Exception in thread "main" java.lang.NoClassDefFoundError: PackageTest

Where did it get that 'PackageTest' thing from? Have you put that in your manifest file? You are just giving your .jar file so the jvm should read a manifest file and find a main class in there, package name and all.

kind regards,

Jos

[Norm]

Please post the contents of the jar's manifest file.
Also show the package name and class name for the class containing the main() method.

[franklyn@bellsouth.net]

Hi JosAH,

Fellow are the files and comamnds.
Also the test.jar file is in the CLASSPATH environment variable

Thx

PackageTest.java:

package com.bcs.util; // com.bcs.util package

public class PackageTest
{
public static void main(String[] args)
{
while (Console.askYorN("Keep going?") ) {
System.out.println("D 'oh!");
}

}

}

Console.java


package com.bcs.util;


import java.util.Scanner;

public class Console
{
static Scanner sc = new Scanner(System.in);

public static boolean askYorN(String prompt)
{
while (true) {
String answer;
System.out.print("\n" + prompt + " (Y or N)" );
answer = sc.next();
if(answer.equalsIgnoreCase("Y"))
return true;
else if (answer.equalsIgnoreCase("N"))
return false;
}


}
}

The above *.java files are in ~/javaclasses/src.com.bcs.util

The package, test.jar and test.mf are in the ~/javaclasses/com.bcs/util

test.mf:

Main-Class: PackageTest

simon@ohare:~/javaclasses/com/bcs/util> jar tf test.jar
META-INF/
META-INF/MANIFEST.MF
PackageTest.class
Console.class

The jar command is successful:

simon@ohare:~/javaclasses/com/bcs/util> jar cfm test.jar test.mf *.class
simon@ohare:~/javaclasses/com/bcs/util>

simon@ohare:~/javaclasses/com/bcs/util> jar cfm test.jar test.mf *.class
simon@ohare:~/javaclasses/com/bcs/util> java -jar test.jar
Exception in thread "main" java.lang.NoClassDefFoundError: PackageTest (wrong name: com/bcs/util/PackageTest)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader. java:632)
at java.lang.ClassLoader.defineClass(ClassLoader.java :616)
at java.security.SecureClassLoader.defineClass(Secure ClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader .java:283)
at java.net.URLClassLoader.access$000(URLClassLoader. java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java: 197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 07)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 48)
Could not find the main class: PackageTest. Program will exit.
simon@ohare:~/javaclasses/com/bcs/util>

[Norm]

NoClassDefFoundError: PackageTest (wrong name: com/bcs/util/PackageTest)

The JVM was looking for the short name and found the longer name with a package path.

Your class is in a package. You need to include the package path in the Main-Class field:
Main-Class: com.bcs.util.PackageTest

[franklyn@bellsouth.net]

Hi Norm,

I make the change to the test.mf file, but I still have the same problem. I remember also doing just that before posting this problem

Thx

simon@ohare:~/javaclasses/com/bcs/util> jar cmf test.jar test.mf *.class
simon@ohare:~/javaclasses/com/bcs/util> java -jar test.jar
Exception in thread "main" java.lang.NoClassDefFoundError: PackageTest (wrong name: com/bcs/util/PackageTest)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader. java:632)
at java.lang.ClassLoader.defineClass(ClassLoader.java :616)
at java.security.SecureClassLoader.defineClass(Secure ClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader .java:283)
at java.net.URLClassLoader.access$000(URLClassLoader. java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java: 197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 07)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 48)
Could not find the main class: PackageTest. Program will exit.

[Norm]

Please show the contents of the manifest file that is in the jar file.
Also you need to position the current directory when the jar command is issued to include the package path to the class file so that it is in the jar file. You should be in the folder containing the com folder. The reference to the class files should include the path to them. Here's some lines from a batch file I use to create a jar file:

SET JarName=%DEV_HOME%\JavaDevelopment\HTTPServer\Serv lets.jar
%DEV_DRIVE%
cd %DEV_HOME%\JavaDevelopment\HTTPServer\
jar -cfm %JarName% servlets\Servlets.mnf servlets\*.class servlets\cart\*.class servlets\database\*.class servlets\htmlchat

cd %DEV_HOME%\JavaDevelopment\HTTPServer\servlets\
jar -uf %JarName% rmibook\*.class rmibook\chat\*.class rmibook\chat\Client\*.class rmibook\chat\Server\*.class rmibook\database\*.class rmibook\database\DBServer\*.class rmibook\timeserver\*.class rmibook\util\*.class

Here

[franklyn@bellsouth.net]

Hi Norm,

Here is the content of the manifest file and a listing of the current directory
where the jar executable is made. But I still get the same problem. The test.jar file is also in the CLASSPATH.

Thx


simon@ohare:~/javaclasses/com/bcs/util> jar tf test.jar
META-INF/
META-INF/MANIFEST.MF
Console.class
PackageTest.class


simon@ohare:~/javaclasses/com/bcs/util> ls -lt
total 16
-rw-r--r-- 1 simon users 2659 2010-08-25 22:18 test.mf
-rw-r--r-- 1 simon users 563 2010-08-25 22:15 PackageTest.class
-rw-r--r-- 1 simon users 982 2010-08-25 22:15 Console.class
-rw-r--r-- 1 simon users 1448 2010-08-25 19:57 test.jar
simon@ohare:~/javaclasses/com/bcs/util>

simon@ohare:~/javaclasses/com/bcs/util> jar -cfm test.jar test.mf /home/simon/javaclasses/com/bcs/util/*.class

simon@ohare:~/javaclasses/com/bcs/util> java -jar test.jar
Exception in thread "main" java.lang.NoClassDefFoundError: com/bcs/util/PackageTest
Caused by: java.lang.ClassNotFoundException: com.bcs.util.PackageTest
at java.net.URLClassLoader$1.run(URLClassLoader.java: 202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 07)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 48)
Could not find the main class: com.bcs.util.PackageTest. Program will exit.
simon@ohare:~/javaclasses/com/bcs/util>

[JosAH]

META-INF/
META-INF/MANIFEST.MF
Console.class
PackageTest.class

I can see an entry 'PackageTest.class' in your .jar but no 'com/bcs/util/PackageTest.class' entry. You have stored a wrong file in your .jar.

kind regards,

Jos

[Tolls]

simon@ohare:~/javaclasses/com/bcs/util> jar tf test.jar

You are jarring the class files, but ignoring the package structure.
You need to do as Norm said and jar from the package (in your case from the javaclasses directory).

[franklyn@bellsouth.net]

Thx To Norm and Jos

The below works. The package directory is the directory that contains the package. It can be very confuse since a package has the form as a directory.

Thx again

simon@ohare:~/javaclasses> jar cfm test.jar com/bcs/util/test.mf com/bcs/util/*.class
simon@ohare:~/javaclasses> jar tf test.jar
META-INF/
META-INF/MANIFEST.MF
com/bcs/util/Console.class
com/bcs/util/PackageTest.class
simon@ohare:~/javaclasses> java -jar test.jar

[Norm]

package has the form as a directory.

Yes it is that.
packages and classpath are one of the problems students have. Hopefully you've got it now and can move on. Write a script to create the jar file and you'll have something to refer back to if you forget how later.

[JosAH]

Thx To Norm and Jos

The below works. The package directory is the directory that contains the package. It can be very confuse since a package has the form as a directory.

Thx again

simon@ohare:~/javaclasses> jar cfm test.jar com/bcs/util/test.mf com/bcs/util/*.class
simon@ohare:~/javaclasses> jar tf test.jar
META-INF/
META-INF/MANIFEST.MF
com/bcs/util/Console.class
com/bcs/util/PackageTest.class
simon@ohare:~/javaclasses> java -jar test.jar

Yup, that's what we were trying to tell you all the time ;-) The system class loadee uses directory structures (optionally in a .jar) as the only means of determining the package structure. If you had used your own classloader you could've used your own structure. The class loader loads a class a.b.yourClass by looking for an entry yourClass.class in directories a/b/ pointed to by the classpath value(s). Simple and consistent ...

kind regards,

Jos