Develop Reference

Java Ant Job how to ship Log4j jar with my jar

Just trying to upgrade some old stuff and part of that I need to bundle my custom jar which uses Log4j. I did add the following for my <javac> task which compiles successfully.
<path id="my.classpath">
<fileset dir="${mainpath}">
<include name="**/*log4j*.jar"/>
</fileset>
</path>
<javac srcdir="src/java" destdir="build/filez/java" debug="on" deprecation="no"
includes="my/instruments/**/*, org/apache/log4j/**/*">
<classpath refid="my.classpath"/>
</javac>
However, In my <jar> job I cannot see any log4j dependency packed with my custom jar. This might be a silly question, but how do ensure that my custom-jar does not fail when called from another application since the dependency isn't packed? Will it be okay as long as log4j has been loaded by classloader in the target application?
Additionally, do I need to add something in my Manifest for this?
I cannot use Maven (yes I know) for a little while, so cannot solve this problem with maven

You can use One-JAR to package your code along with it's dependencies into one big executable JAR.
It can be used either as a standalone tool from the command line or as a task defined in build.xml.
<!-- Construct the One-JAR file -->
<one-jar destfile="hello.jar" manifest="hello.mf">
<main>
<!-- Construct main.jar from classes and source code -->
<fileset dir="${classes.dir}/src"/>
</main>
<lib>
<fileset file="${build.dir}/lib.jar" />
</lib>
</one-jar>

Ant can't find classpath classes

So I'm extending my company's ant build script to add in a special module we want build in some cases. I've written an ant script that points to where I know the compiled class files for the rest of our codebase are, because they get compiled earlier in the build process. I know with 100% certainty the files are in this location.
However, whenever I try to compile this module, the classpath reference can't see those classes, and I get a bunch of "package does not exist" and "can't find symbol" errors.
I just can't seem to figure out what I'm doing wrong. Hoping for help here.
Here's my build script code:
<property name="classpath" value="${dir.dev}/out/production/Main"
<path id="pfClasspath">
<fileset dir="${classpath}">
<include name="**/*.class"/>
</fileset>
<fileset dir="${dir.dev.lib}">
<include name="**/*.jar" />
</fileset>
<fileset file="${lib.json}" /> <!-- TODO try removing this -->
</path>
<target name="compile" depends="prepare">
<javac source="1.7" classpathref="pfClasspath" srcdir="${dir.project}/src" destdir="${dir.project.build.classes}" />
</target>
The directory the "classpath" property is pointing at 100% contains all of the class files for the rest of the project. That level is the equivalent of the "src" directory on the sources side, immediately within it are the com/companyName/etc... folders.
My code contains references to the classes compiled at this location. Yet ant isn't finding them. Any help?

Try
<path id="pfClasspath">
<pathelement path="${classpath}" />
...
</path>
instead. Specifying the classpath does not mean to specify every single class file that's on the classpath, which is what you do when you define your <path> element using a <fileset>.

Why combine all jars together?

I have create RESTful web service based on the JAX-RS and used Jersey embedded web server. My ant script compiles code successfully while it gives me error ClassNotFoundException when I run my main class. So after doing research I came up with solution & here it goes java build ant file with external jar files . What I did was created a bundled jar file try to execute that & it works perfectly fine. I want to know the reason behind :
why this solution works ?
Why I should combine all jar file ?
Is it similar to war file which we create following J2EE architecture otherwise war will not be extracted by server ( say TOMCAT ) & in my case jar file for Jersey embedded HTTP server?
EDIT:
Here is my ant build.xml file
<property name="lib.dir" value="${user.dir}/lib"/>
<property name="build.dir" value="${user.dir}/build"/>
<property name="build.lib.dir" value="${build.dir}/lib"/>
<property name="build.classes.dir" value="${build.dir}/classes"/>
<property name="src.dir" value="${user.dir}/src/main/java"/>
<property name="main.class" value="com.assignment.ConsoleServer"/>
<path id="classpath">
<fileset dir="${lib.dir}" includes="**/*.jar"/>
</path>
<target name="clean">
<delete dir="${build.dir}"/>
</target>
<target name="init" depends="clean">
<!-- Create the build directory structure used by compile -->
<mkdir dir="${build.dir}"/>
<mkdir dir="${build.classes.dir}"/>
</target>
<target name="copy_jars" depends="init" >
<copy todir="${build.lib.dir}" >
<fileset dir="${lib.dir}">
<include name="**/*.jar" />
</fileset>
</copy>
</target>
<target name="compile" depends="copy_jars">
<javac srcdir="${src.dir}" destdir="${build.classes.dir}" classpathref="classpath" includeantruntime="false"/>
</target>
<target name="jar" depends="compile">
<jar destfile="${build.dir}/${ant.project.name}.jar" basedir="${build.classes.dir}">
<manifest>
<attribute name="Main-Class" value="${main.class}"/>
</manifest>
<zipgroupfileset dir="${lib.dir}" includes="*.jar"/>
</jar>
</target>
<target name="run" depends="jar">
<java fork="true" classname="${main.class}">
<classpath>
<path refid="classpath"/>
<path location="${build.dir}/${ant.project.name}.jar"/>
</classpath>
</java>
</target>
Here is my folder structure
P.S. I am not java expert so pardon me if this question is stupid.

Why this solution works?
In your particular case, you probably didn't include all of the necessary dependencies in your deployment in your previous. (It is not clear from your question how you were originally doing the deployment.)
Now you have put all of the application and dependent class files, etc into one JAR file, and presumably you are deploying / running that file. It works because now it has everything that it needs to run ... which it didn't before.
Why I should combine all jar file?
In your case I suspect that it was not strictly necessary. There was probably a way to "deploy" all of the dependencies without combining them into a single JAR file.
However, there is one case where a "uber-jar" has advantages. That is when the JAR is intended to be an "executable" JAR, and you want to be able to distribute / install it as a single file. (And executable JAR
file can refer to external JARs, etc, but the way that you have to do
it is "fragile".)
Is it similar to war file ... ?
Sort of, though a WAR file contains JAR files ... and typically other kinds of resources that the web-container understands.

The solution works because you packed all you service classes and depending libraries in one jar. That jar and everything inside will be in the class path and visible to your execution virtual machines class loader.
If you leave your depending libraries out your Jersey Web server needs to have them on it's class path, then you wouldn't get ClassNotFoundExcpetion
You shouldn't pack web application in single jar. You should crate war file where you dependencies will be placed inside WEB-INF/lib. You would easily then deploy that war on any application server. Switching to Maven instead of Ant can help a lot.
EDIT: After you added more details to description and ant
If you don't want to use fat-jar you can either
modify your antjava task to specify classpath that will reference
all external libraries (basically telling ant how to build
-classpath parameter for java -jar command
even better, modify your javac ant task by making complete Manifest file that specifies Class-Path correctly, take a better
look at the solution (at the bottom) of the answer you linked (java build ant file with external jar files)
For completness reference on Manifest here

How do I create a Jar file from my program

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

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".

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.

Log4j not being added to classpath in Ant

I'm attempting to add Log4j to my project's classpath in Ant which creates an executable JAR, but it appears that it's not being added properly.
Here is the path component of my Ant build script:
<path id="classpath.compile">
<fileset dir="${dir.myLibs}">
<include name="**/*.jar"/>
</fileset>
<pathelement location="${dir.webContent}/WEB-INF/lib/log4j.jar" />
</path>
The compile target looks like this:
<target name="-compile">
<javac destdir="${dir.binaries}" source="1.6" target="1.6" debug="true" includeantruntime="false">
<src path="${dir.source}"/>
<classpath refid="classpath.compile"/>
</javac>
</target>
Tthe target that creates the JAR:
<target name="-createJar" >
<jar jarfile="${path.jarFile}"
manifest="${dir.source}\META-INF\MANIFEST.MF">
<fileset dir="${dir.binaries}" casesensitive="yes">
<exclude name="**/*.java"/>
</fileset>
</jar>
</target>
Lastly, the MANIFEST.MF:
Manifest-Version: 1.0
Class-Path: ../../../WebContent/WEB-INF/lib/log4j.jar (what is this pathing relative to?)
Main-Class: foo.Bar
The JAR is created, but when I execute it, I get:
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Logger...
Any thoughts as to what I'm doing wrong?

It looks from the classpath in your MANIFEST that you are trying to reference a jar inside your jar. The only two ways to make that work AFAIK are 1) a special classloader, like #infosec812 mentions, or 2) by exploding the jar dependencies directly into the root of your jar. Either is workable, but I don't see either of them happening in your ant script.
If you're trying to reference a jar outside of your jar, your relative classpath is relative to the location of the jar you are executing. Make sure the referenced jar exists in that location.

I'm guessing that you're running the Java program as follows
java -jar myapp.jar
In this case you'll need to specify the Class-Path attribute in the manifest. I suggest you also check out the manifestclasspath task

Creating the jar does not include the linked libraries in the jar. You would have to have the required jars in your execution classpath in order to run it that way. Or, you could use the solution I use, which is to create a one-jar archive. It adds a specialized class loader for your application into the resulting jar and also packages your required jars in to the final executable jar. It works really well for deploying neat, simple to use packages.