blocks|key|1646591|text|在编译/运行代码时，需要将.jar文件放入类路径中。然后，您只需在.jar中使用类的标准导入。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1646592|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You need to put the .jar file into your classpath when compiling/running your code. Then you just use standard imports of the classes in the .jar.

blocks|key|1431620|text|并不是每个jar文件都是可执行的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1431621|现在，您需要在java文件中导入jar下的类。例如,|1431622|import+org.xml.sax.SAXException;|code-block|syntax|javascript|1431623|如果您正在使用IDE，那么您应该参考它的文档。或者至少指定您在此线程中使用的是哪一个。这将使我们能够进一步帮助您。|1431624|如果您没有使用任何集成开发环境，那么请查看javac+-cp选项。但是，更好的做法是将程序打包到jar文件中，并在其中包含所有需要的jar。然后，为了执行你的jar，比如|offset|length|style|CODE|1431625|java+-jar+my_program.jar|1431626|您的jar中应该有一个META-INF/MANIFEST.MF文件。有关操作方法，请参阅here。|1431627|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/8/docs/technotes/tools/windows/javac.html|1|https://stackoverflow.com/questions/2848642/how-to-setup-main-class-in-manifest-file-in-jar-produced-by-netbeans-project^0|0|0|0|0|1C|3|1U|3|27|3|L|9|0|0|0|2|3|B|K|18|4|1|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|16|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|17|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|18|8|@$M|19|N|1A|O|P]|$M|1B|N|1C|O|P]|$M|1D|N|1E|O|P]]|9|@$M|1F|N|1G|1|1H]]|A|$]]|$1|Q|3|R|5|F|7|1I|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|1J|8|@$M|1K|N|1L|O|P]|$M|1M|N|1N|O|P]]|9|@$M|1O|N|1P|1|1Q]]|A|$]]|$1|U|3|-4|5|6|7|1R|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]|12|$5|X|Y|Z|A|$10|13]]]]

Not every jar file is executable.

Now, you need to import the classes, which are there under the jar, in your java file. For example,

<pre><code>import org.xml.sax.SAXException;
</code></pre>

If you are working on an IDE, then you should refer its documentation. Or at least specify which one you are using here in this thread. It would definitely enable us to help you further.

And if you are not using any IDE, then please look at <a href="http://docs.oracle.com/javase/8/docs/technotes/tools/windows/javac.html" rel="noreferrer">javac -cp</a> option. However, it's much better idea to package your program in a <code>jar</code> file, and include all the required <code>jar</code>s within that. Then, in order to execute your <code>jar</code>, like,

<pre><code>java -jar my_program.jar
</code></pre>

you should have a <code>META-INF/MANIFEST.MF</code> file in your <code>jar</code>. See <a href="https://stackoverflow.com/questions/2848642/how-to-setup-main-class-in-manifest-file-in-jar-produced-by-netbeans-project">here</a>, for how-to.

blocks|key|1646689|text|正如workmad3所说，您需要jar文件位于类路径中。如果你从命令行编译，那就意味着要使用-classpath标志。(避免使用CLASSPATH环境变量；这是一个令人头疼的问题。)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1646690|如果您使用的是IDE，请让我们知道是哪种IDE，我们可以帮助您执行特定于该IDE的步骤。|1646691|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

As workmad3 says, you need the jar file to be in your classpath. If you're compiling from the commandline, that will mean using the -classpath flag. (Avoid the CLASSPATH environment variable; it's a pain in the neck IMO.)

If you're using an IDE, please let us know which one and we can help you with the steps specific to that IDE.

blocks|key|1646743|text|您需要在类路径中添加jar文件。要编译您的java类：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1646744|javac+-cp+.;jwitter.jar+MyClass.java|code-block|syntax|javascript|1646745|要运行您的代码(假设MyClass包含一个main方法)：|1646746|java+-cp+.;jwitter.jar+MyClass|1646747|您可以将jar文件放在任何位置。如果jar文件与您的java文件位于同一目录中，则可以使用上面的方法。|1646748|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You need to add the jar file in the classpath. To compile your java class:

<pre><code>javac -cp .;jwitter.jar MyClass.java
</code></pre>

To run your code (provided that MyClass contains a main method):

<pre><code>java -cp .;jwitter.jar MyClass
</code></pre>

You can have the jar file anywhere. The above work if the jar file is in the same directory as your java file.

I read the Java tutorials on Sun for JAR files, but I still can't find a solution for my problem. I need to use a class from a jar file called jtwitter.jar, I downloaded the file, and tried executing it (I found out yesterday that .jar files can be executed by double clicking on them) and Vista gave me an error saying "Failed to load Main-Class Manifest attribute from [path]/jtwitter.jar".

The guy who coded the .jar file wants me to import it, but where do I store the .jar file to import it in my code? I tried putting both the .jar file and my .java file in the same directory, didn't work.

The file I'm trying to work for is here: <a href="http://www.winterwell.com/software/jtwitter.php" rel="noreferrer">http://www.winterwell.com/software/jtwitter.php</a>

I'm using JCreator LE.

How to use classes from .jar files?

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我阅读了Sun上关于JAR文件的Java教程，但我仍然找不到解决问题的方法。我需要使用一个名为jtwitter.jar的jar文件中的一个类，我下载了这个文件，并尝试执行它(我昨天发现.jar文件可以通过双击它们来执行)，Vista给我一个错误，说“无法从路径/jtwitter.jar加载主类清单属性”。编写.jar文...

问如何使用.jar文件中的类？
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