A JAR (Java ARchive) is a way of packaging together all of the resources associated with a program (class files, images, sounds, etc.). Putting your program in a JAR allows it to be distributed as a single executable file, saving space and simplifying the download process. The information in this tutorial applies to Java version 1.2 or higher. For more information about JAR files, follow Sun’s tutorial<\/A>. To learn about signing the JAR<\/A> and Java Web Start<\/A>. <\/P>
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A simple example.<\/B> Let’s say we wanted to distribute the simple program Hello.java<\/A> as a JAR. First, we create a text file named Hello.mf<\/TT> which contains: <\/P> <\/P> Creating an executable JAR file.<\/B> Here is the general procedure for creating an executable JAR: <\/P> <\/P> <\/P><\/LI> <\/P><\/LI> <\/P><\/LI> <\/P><\/LI> Accessing resources in a JAR.<\/B> In general, the first step in accessing a JAR resource involves creating a URL. This might require modifying your program. For example, you can no longer use the following code fragment to read in an image that is stored in a file as follows <\/P> JAR Subdirectories.<\/B> The JAR format also support storing files in a directory structure. Consider a program The Manifest should read: <\/P> To create the JAR, type: <\/P> The contents listing appears as: <\/P> Notice that the directory structure is still preserved (the META-INF directory is created to hold the manifest and other general information about the JAR). <\/P> Distributing your Application as an executable JAR file A JAR (Java ARchive) is a way of packaging together all of the resources associated with a program (class files, images, sounds, etc.). Putting your program in a JAR allows it to be distributed as a single executable file, saving space and simplifying the download process. The … Continue reading Distributing your Application as an executable JAR file<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-353","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/posts\/353","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.strongd.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=353"}],"version-history":[{"count":0,"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/posts\/353\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.strongd.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=353"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.strongd.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=353"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.strongd.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=353"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nManifest-Version: 1.0
\nMain-Class: Hello
\n<\/PRE><\/BLOCKQUOTE>Then, we create the archive by typing:
\njar cmf Hello.mf Hello.jar Hello.class Hello.java
\n<\/PRE><\/BLOCKQUOTE>and run it by typing:
\njava -jar Hello.jar
\n<\/PRE><\/BLOCKQUOTE>The file Hello.jar<\/A> can now be downloaded and executed.
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\nManifest-Version: 1.0
\nMain-Class: name of class containing main<\/EM>
\n<\/PRE><\/BLOCKQUOTE>The name of the file should end with the .mf<\/TT> suffix. It is important that the file ends with a blank line.
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\njar cmf manifest-file<\/I> jar-file<\/I> input-files<\/I><\/PRE><\/BLOCKQUOTE>The input-files<\/I> must include any class files, images, sounds, etc. that your program uses. Optionally, you can include the program’s
.java<\/CODE> files in the JAR. See below for adding directories ot the JAR.
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\njar tf jar-file<\/I><\/PRE><\/BLOCKQUOTE>
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\njava -jar jar-file<\/I><\/PRE><\/BLOCKQUOTE>If the application is GUI-based, you can also launch it by double-clicking the JAR file. <\/LI><\/OL>
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\nImage image = Toolkit.getDefaultToolkit().getImage(filename);
\n<\/PRE><\/BLOCKQUOTE>Instead, create the URL<\/TT> object using
\nURL url = getClass.getResource(filename);
\nImage image = Toolkit.getDefaultToolkit().getImage(url);<\/PRE><\/BLOCKQUOTE>Or, if the code is in a static method of class X<\/TT>, then create the URL with
\nURL url = X.class.getResource(filename); <\/PRE><\/BLOCKQUOTE>Now, the resource can be accessed the same way, regardless of whether it is in a JAR or the current directory. See the method
play(filename)<\/CODE> in StdDraw.java<\/A> for an example involving audio clips, and and the constructor In(String s)<\/CODE> in In.java<\/A> for an example involving text files.
\nSample.java<\/CODE>, which uses the Turtle Graphics interface to display a collection of pictures stored in a subdirectory called images<\/CODE>. Our working directory<\/A> looks like: <\/P>
\n![](\"http:\/\/www.cs.princeton.edu\/introcs\/85application\/jar\/chart2.gif\")
<\/P>
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\nManifest-Version: 1.0
\nMain-Class: Sample
\n<\/PRE><\/BLOCKQUOTE>
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\njar cmf Sample.mf Sample.jar Sample.class Turtle.class Sample.java Turtle.java images
\n<\/PRE><\/BLOCKQUOTE>
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\nMETA-INF\/
\nMETA-INF\/MANIFEST.MF
\nSample.class
\nTurtle.class
\nSample.java
\nTurtle.java
\nimages\/
\nimages\/image1.gif
\nimages\/image2.gif
\nimages\/image3.gif
\n<\/PRE><\/BLOCKQUOTE>
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