Creating a JAR with main class def.

Hello Amigos,
I am having problems creating a jar file. My problem is that when I create the jar file and insert this line in my manifest file
Main-Class: classnamewhere classname is what ever class you want as explain here:
http://java.sun.com/developer/Books/javaprogramming/JAR/basics/run.html
Then I have the jar file and double click it and get the Fail to load Main-Class error.
This is what I am typing in the command line:
jar cmf MANIFEST.MF myapp.jar *.class
When I go back and extract all the files out of the jar file the manifest files looks like this:
Manifest-Version: 1.0
Created-By: 1.3.1 (IBM Corporation)Thanks in advance

No ofense but... You got to be kidding me!?!?!Not kidding at all. Had you read the online tutorial, you'd have found the following line:
Warning: The text file must end with a new line or carriage return. The last line will not be parsed properly if it does not end with a new line or carriage return.
Have you tried it yet?

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Dear all,
I want to create a jar file with only classes.My class files and java files are in different folders under com .
say
com
in com there are two folders
folder 1 -- subfolder 1
folder 2 -- subfolder 2
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If i want to create a jar file from com directory how should i give the jar command.Again my jar should contain only .class files.
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Thanks
lekshmi

It doesn't work.Says "No such class or directory"
Any other way Or is it possible to do so?Read the link I posted and create the statement to make your structure. I was thinking you were inside the com directory but if you are above it you will need something like this instead:
jar -cf test.jar com\*.class com\subfolder1\*.class com\subfoler2\*.class
But either way don't just copy and past this. Think about what is does so that you can make it work for you.
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Hello all,
usually it is required, that that jar file (let me call it "main jar"), which contains the main class (by which the application is entered), has to be the first jar in the order of the jar files within <resources> of the jnlp file.
Now if a patch of the "main jar" is created which doesn't contain the main class, where has this patch jar to be arranged in the jnlp file? Because it is a patch jar, usually it must be arranged in front of this main jar, that it is read before the main jar to load the patched class correctly. On the other hand it is required, that the jar with the main class has to be the first ...
Therefore again: Where has that patch jar, described, to be arranged?
Thanks for all good advices.
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The main jar does not need to be first, if you explicitly add the argument main="true":
<jar href="jar2.jar"/>
<jar href="jar1patch.jar" />
<jar href="jar1.jar" main="true"/>
the first jar is used as main only if there is no jar listed with main="true".
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Well, I think I've found one on sourceforge: http://genjar.sourceforge.net/
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package org.igis.assjar;
* <p>Read a class file stream and return all the referenced classes from the
* class.</p>
* @author malcolmm
public class GetClassRefs {
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    private static final byte CONSTANT_InterfaceMethodRef = 11;
    private static final byte CONSTANT_String = 8;
    private static final byte CONSTANT_Integer = 3;
    private static final byte CONSTANT_Float = 4;
    private static final byte CONSTANT_Long = 5;
    private static final byte CONSTANT_Double = 6;
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    private static final byte CONSTANT_Utfs = 1;
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        lengths[CONSTANT_MethodRef] = 5;
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        lengths[CONSTANT_Float] = 5;
        lengths[CONSTANT_Long] = 9;
        lengths[CONSTANT_Double] = 9;
        lengths[CONSTANT_NameAndType] = 5;
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        in.skipBytes(4);
        int cpCount = in.readUnsignedShort();
        constTable = new Object[cpCount];
        nRefs = 0;
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                        if(clsName.charAt(0) == '[') {
                            do
                                clsName = clsName.substring(1);
                            while(clsName.charAt(0) == '[');
                            if(clsName.charAt(0) == 'L' && clsName.endsWith(";"))
                                clsName = clsName.substring(1, clsName.length() - 1);
                        constTable[i] = clsName;
                    break;
                case CONSTANT_Class:
                    nRefs++;
                    constTable[i] = new Integer(in.readUnsignedShort());
                    break;
                case CONSTANT_Long:
                case CONSTANT_Double:
                    i++;
                    in.skipBytes(8);
                    break;
                default:
                    if(tag < 0 || tag >= lengths.length || lengths[tag] == 0)
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        in.skipBytes(2);
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        int cpp = ((Integer)constTable[thisClass]).intValue();
        if(!(constTable[cpp] instanceof String))
            throw new ClassFormatError("Invalid main class pointer");
        mainClass = (String)constTable[cpp];
        refs = new String[nRefs - 1];
        int j = 0;
        for(int i = 1; i < constTable.length; i++) {
            Object entry = constTable;
if(entry instanceof Integer) {
int idx = ((Integer)entry).intValue();
if(idx < 1 || idx >= constTable.length)
throw new ClassFormatError("Out of range class reference");
if(constTable[idx] instanceof String) {
if(i == thisClass)
mainClass = (String)constTable[idx];
else
refs[j++] = (String)constTable[idx];
else
throw new ClassFormatError("Class reference not string");
public String getMainClass() {
return mainClass;
public String[] getRefs() throws ClassFormatError {
return refs;

Create a .jar with a database in mysql????

Hi !!!!
I create a script in .java, and I have none error. My script use a database, to read and to save some data.
I create a Manifest.mf
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Main-Class: AutoPlanning
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Thanks !!!

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jcommon-1.0.0-rc1.jar
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j

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Creating a JAR with main class def.

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