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Thread: Creating a jar File

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    Default Creating a jar File

    Hello Everyone,

    I currently finding a way how can i package a required/dependency JAR with my runnable JAR only using a command prompt like
    how the ECLIPSE IDE export RUNNABLE JAR
    im running on a linux environment, is there a way to do this.

    i can only make Runnable Jar without the required JAR by using this command

    jar cvfm Test.jar manifest.txt package/*.class

    Thanks in advance , Happy Codings


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    Default Re: Creating a jar File

    Quote Originally Posted by skate101 View Post
    i can only make Runnable Jar without the required JAR by using this command

    jar cvfm Test.jar manifest.txt package/*.class
    External jars must be declared into the manifest. The manifest should have a line like:

    Class-Path: lib/other1.jar lib/other2.jar

    The "lib" sub folder is just an example. Other jars must be tied with a relative path to your main jar.

    And note: if you write the manifest yourself, beware about the line length limitation, from jar specs:
    No line may be longer than 72 bytes (not characters), in its UTF8-encoded form. If a value would make the initial line longer than this, it should be continued on extra lines (each starting with a single SPACE)
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

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    skate101 (March 6th, 2014)

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    Default Re: Creating a jar File

    Welcome to the Forum! Please read this topic to learn how to post code correctly and other useful tips for newcomers.

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    Default Re: Creating a jar File

    Hello Sir andbin,

    Great. it works fine when my compiled classes , and library are all in same directory.


    Thank you Sir. but can i asked again .

    Here's my scenario , considering the following directory
    home/skate/classes/ ----> contains all my compiled classes organized in package
    home/skate/bin/ ----> will contain my runnable jar
    home/skate/manifest/ ----> contain the Manifest File
    home/skate/lib/ ----> contains all required JAR files

    when i executed this command:

    jar cvfm ./bin/Skate.jar ./manifest/Manifest.txt ./classes/* ./lib/*

    it created the Skate.jar inside the bin directory but when i execute the jar, it throws an exception

    Exception in thread "main" java.lang.NoClassDefFoundError:

    i understand that java cannot find the entry point because in theManifest file i declared the entry point like this

    Main-Class: com.main.Main


    and when i checked the Skate.jar, i noticed the "classes" directory are also bundle with the Skate.jar

    classes/com/main/Main.class

    so the question is how can i get rid with the parent directory "classes". for me to bundle only the Main.class in my Skate.jar

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    Default Re: Creating a jar File

    Quote Originally Posted by skate101 View Post
    when i executed this command:

    jar cvfm ./bin/Skate.jar ./manifest/Manifest.txt ./classes/* ./lib/*
    First: it has no sense (and it's useless) that you put external jars into your jar. The JVM will not search jars into your jar!

    Quote Originally Posted by skate101 View Post
    it created the Skate.jar inside the bin directory but when i execute the jar, it throws an exception

    Exception in thread "main" java.lang.NoClassDefFoundError:

    i understand that java cannot find the entry point because in theManifest file i declared the entry point like this

    Main-Class: com.main.Main


    and when i checked the Skate.jar, i noticed the "classes" directory are also bundle with the Skate.jar
    It's not correct that the jar contains the 'classes' directory. If you have a class com.main.Main, the jar must contain a "com" folder at the root of the jar (the "com" contains a "main" folder, etc...).

    Use the -C option of jar tool (see official documentation for further informations).
    Instead to use:

    ./classes/*

    use:

    -C ./classes .


    Final note: if you want to keep the relation
    ....anything/bin/yourjar
    ....anything/lib/otherjars

    then the Class-Path entry in your manifest must be like:

    Class-Path: ../lib/xyz1.jar ../lib/xyz2.jar

    because the JVM must know to go "up" (..) and then enter into lib folder to find the jar.
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

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    Default Re: Creating a jar File

    Thank you again Sir.

    -C ./classes . really works

    from the start i already knew that using this command "jar cvfm ./bin/Skate.jar ./manifest/Manifest.txt ./classes/* ./lib/*"
    in command prompt will produce a runnable jar that CANNOT search its dependency jar inside of it .

    Okay Sir, back to my original question in my FIRST post.

    I currently finding a way how can i package a required/dependency JAR with my runnable JAR only using a command prompt like
    how the ECLIPSE IDE export RUNNABLE JAR .

    or should i rephrase my question..

    Is there a way in creating a RUNNABLE jar via Command prompt be like the way how the ECLIPSE IDE exports its RUNNABLE JAR package with the dependency JARS. ?

    Thank you again Sir. and God Bless .

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    Default Re: Creating a jar File

    Quote Originally Posted by skate101 View Post
    Is there a way in creating a RUNNABLE jar via Command prompt be like the way how the ECLIPSE IDE exports its RUNNABLE JAR package with the dependency JARS. ?
    Eclipse has a "Fat Jar" plugin that can create a jar containing your classes/resources and all classes/resources from all dependencies.
    Technically it's possible to do this from command prompt but requires "some" work: a) first, you need to unpack (unzip) all required jars somewhere, b) you need to "pull in" all those classes/resources using that same -C command that now you know.

    However having a single jar with all classes/resources from all dependencies is not a good thing, and at least for 2 reasons:
    1) Licensing problems: the producer of a library could disagree about this type of bundling for any reason.
    2) Update/deploy problems: if you change just only a small thing in your application, you need to recreate this big jar. This may not be a big problem for you. But if the application is deployed through internet (e.g. you send the jar to a customer, or there is an automatic update system, or you store it with FTP somewhere) the big size may be a problem.
    And if a dependency need to be updated (e.g. you choose another version) you need to redo the a) step for this library.

    So please, don't do this.
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

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    skate101 (March 9th, 2014)

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    Default Re: Creating a jar File

    Thank you Sir andbin . you help me a lot God Bless Sir .

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