How do I create a Jar file from my program

Question

I am using eclipse, and I am having difficulty in creating jar files.

So I have codes like getClass().getResource("/imagesfolder/dog.jpg"). How would I create Jar files such that the folder containing my images will also be included. Because error occurs if my Jar file is not in my bin folder with the class files and the imagesfolder.

I tried File>Export>Java>Executable Jar>Save in desktop but when I double click it, it does not start. I tried cmd and it worked but with errors that it can't find imagesfolder.

How will I do a jar file in a separate directory that executes with a double click

Answer 1

ANT is The Way

In eclipse you can use Ant to build your .jar file.

From ant.apache.org

Apache Ant is a Java library and command-line tool whose mission is to drive processes described in build files as targets and extension points dependent upon each other. The main known usage of Ant is the build of Java applications. Ant supplies a number of built-in tasks allowing to compile, assemble, test and run Java applications. Ant can also be used effectively to build non Java applications, for instance C or C++ applications. More generally, Ant can be used to pilot any type of process which can be described in terms of targets and tasks.

Ant is written in Java. Users of Ant can develop their own "antlibs" containing Ant tasks and types, and are offered a large number of ready-made commercial or open-source "antlibs".

Ant is extremely flexible and does not impose coding conventions or directory layouts to the Java projects which adopt it as a build tool.

Software development projects looking for a solution combining build tool and dependency management can use Ant in combination with Apache Ivy.

The Apache Ant project is part of the Apache Software Foundation.

Search with google and you will find many documentation, I will show the basic way to do it.

---

The Build.xml file

First of all create a new file xml, for example "Build.xml" this will be the file that Ant will read.

The you start writing inside it this:

<?xml version="1.0" encoding="UTF-8"?>

This is the basic line you have always to include.

<project name="NameOfYourProject" default="try_jar" basedir=".">

This (with its closing tag </project> at the end of the file, is the main tag, declaring the name of the project and the first task (default) that will be executed, each task is something Ant will do, and is called "Target", you can create a single target that do everything or various target that do few things each, in this case you can create different "flow-chart" that ant will follow. For example I usually create 3 route for Ant: try_jar that is used just to try if all is working in the jar without doing many things, new_version_jar that is the same of try_jar but will update version number, will sign the jar and some other stuff, and javadoc that creates the javadoc for the project. Il will show you the basic try_jar.

<description>
This buildfile is used to build the jar of the game.
</description>

No need to explanation.

<!-- ================= File and Directory Names ==================== -->
<property name="src" location="${basedir}/src" />
<property name="conf" location="${basedir}/conf" />
<property name="build" location="${basedir}/build" />
<property name="dist" location="${basedir}/dist" />
<property name="app.name" value="MyAppName" />
<property name="dist.jarHome" value="${user.home}/MyApplicationMainFolder" />
<property name="app.version" value="0.2" />
<tstamp />
<property name="jar.name" value="${app.name}_${app.version}.${DSTAMP}.jar" />
<property name="jar.completePath" value="${dist.jarHome}/${jar.name}" />

Here we declare the base properties of the jar, we tell it where the source code is, where the build folder should be and so on. We also choose to put all the app in a folder in the base user home (in mac this is /user/UserName/) and create the name for the file that will include the name (obviously) the version and the time when this jar is created. This avoid duplicated or overriding of files that we may want to keep.

<property name="shared.lib" value="${basedir}/lib" />

Here we must specify the directory in which jar files needed by this plugin to run are stored

<!-- =============== Custom Ant Task Definitions =================== -->
<property name="compile.debug" value="true" />
<property name="compile.deprecation" value="false" />
<property name="compile.optimize" value="true" />

This are configuration params for ant

<!-- ================== External Dependencies ======================= -->
<property name="LWJGL" value="lwjgl.jar" />
<property name="Timer" value="timer.jar" />
<property name="Database" value="hsqldb.jar" />
<property name="Splice" value="jarsplice-0.25.jar" />

Here you must specify your external dependencies (something like easymock or powermock if you want to create a test target.

<!-- ================== Compilation Classpath ======================= -->
<path id="compile.classpath">
    <fileset dir="${src}">
        <include name="**/*.java" />
        <exclude name="**/server/*.java"/>
    </fileset>
    <fileset dir="${shared.lib}">
        <include name="**/*.jar" />
    </fileset>
</path>

This is what And (with javac command) will build, you have to specify all the folders you want to build and to add (with <fileset>) any jar that is in the buildpath

<!-- =================== All Target ================================ -->

<!-- ================== Try_jar Target ============================ -->
<target name="try_jar" depends="compile, dist, clean_class_files, run" description="Clean build and dist directories, then compile, create jar and finally run" />

This is our target, as specified in "default" the first line, and will run this. Depends tells Ant what it should do before this target. A you can read it will compile, create the jar (dist), remove the class files, and run it.

<!-- ================== Clean Target ============================== -->

<target name="clean" description="Delete old build and dist directories">
    <delete dir="${build}" />
    <delete dir="${dist}" />
</target>

This is very clear, before to compile a new version we want to remove any old class file to avoid problems. You may think that this is never called, but pay attention to the dependencies of each target.

<!-- ================== Prepare Target ============================= -->

<target name="prepare" depends="clean">
    <mkdir dir="${build}" />
    <mkdir dir="${build}/classes" />
    <mkdir dir="${build}/lib" />
    <copy todir="${build}/lib">
        <fileset dir="${shared.lib}" includes="${Timer}, ${LWJGL}, ${Database}" />
    </copy>
</target>

This prepare the path, creating new needed folders (like build and build/classes) and adding the external dependencies jars.

<!-- ================== Compile Target =========================== -->

<target name="compile" depends="prepare" description="Compile Java sources">

    <mkdir dir="${build}/classes" />
    <javac srcdir="${src}" destdir="${build}/classes" encoding="8859_1" debug="${compile.debug}" deprecation="${compile.deprecation}" optimize="${compile.optimize}" source="1.6" target="1.6">
        <classpath refid="compile.classpath" />
    </javac>
</target>

This is the main compiling target, as you can see it depends on prepare (that depends on clean) so until now we are using all <target> tags.
Ant compile .java files using <javac> tag, that needs to know where the source files are, where to put .class files, the encoding, and the three params we specified earlier.

<!-- =================== Dist Target ================================ -->
<target name="dist" description="Creates Jar archive">
    <!-- Create the time stamp -->
    <tstamp>
        <format property="compile.timestamp" pattern="yyyyMMddHHmm" />
    </tstamp>
    <!-- update version in manifest -->
    <replaceregexp file="${basedir}/manifestClient" match="Implementation-Version: .*" replace="Implementation-Version: ${app.version}.${compile.timestamp}" />
    <!-- Create Jar file -->
    <jar destfile="${jar.completePath}" manifest="${basedir}/manifest">
        <fileset dir="${build}/classes" excludes="**/*.bak" />
        <fileset dir="${src}/" excludes="mh/" />
        <fileset dir="${shared.lib}/native/macosx" />
        <zipfileset src="${shared.lib}/${Timer}" />
        <zipfileset src="${shared.lib}/${LWJGL}" />
        <zipfileset src="${shared.lib}/${Database}" />
    </jar>
</target>

this creates the real jar. <tstamp> and <replaceregexp> are used to update the version in the manifest, you can remove them.
Jar tag will create the .jar file, we specified what files to add in the jar that will be avaible to my classes inside. We have also to specify a manifest that will discuss later.

<!-- =================== Delete .class Target===================== -->
<target name="clean_class_files" description="Delete .class files stored inside build directory and dist folder">
    <delete dir="${build}" />
    <delete dir="${dist}" />
</target>

This target deletes the two folder used to store .class files (and obviously all the files inside).

<!-- ================== Run Target =============================== -->
<target name="run" description="Run MagicHogwarts">
    <java jar="${jar.completePath}" fork="true">
    </java>
</target>

The end of our build.xml file, that is the run target that runs the jar.

This is almost what you need to compile and and the correct resources to a jar, if something is not like you are expecting, simply try few times and all will go right.

This is the manifest:

Manifest-Version: 1.0
Created-By: 1.6.0 (Sun Microsystems Inc.)
Main-Class: package.to.class.with.main
Built-by: Gianmarco
Implementation-Vendor: Gianmarco
Implementation-Title: Title

I hope this will be useful to you.

I am editing few things to make the post better, but no contents will be different.

Answer 2

I have a class TreeIcon; it uses two images, and I store them in a folder 'images' which is within the package of TreeIcon. For whatever reason, I made the package of TreeIcon spacecheck.images (it could just as easily have been com.mycompany.images). Therefore I used following code to access my images:

expandedIcon = new ImageIcon(TreeIcon.class.getResource("images/Expanded.GIF"));

where the 'images' here is the name of the folder containing just the images, not the one that is part of the package. I.E., in my tree structure for the program source, the images are in a folder named spacecheck.images.images.

Note that there's no slash at the start of my string; this means it references a path relative to that of the class. Putting the slash in front of the spec causes getResource to regard the path as absolute within your jar, so I could also have used the string "/spacecheck/images/images/Expanded.GIF".