Java creating jar file

Question

I m learning Java and I have a problem  I created 6 different classes  each has it s own main   method  I want to create executable  jar for each class  that is 6 executable  jar files   So far I tried   java -jar cf myJar jar myClass class   and I get  Unable to access jarfile cf   I m doing something wrong but I don t know what  I m also using Eclipse IDE if that means something

User · Answer

Put all the 6 classes to 6 different projects  Then create jar files of all the 6 projects  In this manner you will get 6 executable jar files

User · Answer

way 1    Let we have java file test java which contains main class testa now first we compile our java file simply as javac test java we create file manifest txt in same directory and we write Main-Class  mainclassname   e g       Main-Class  testa   then we create jar file by this command       jar cvfm anyname jar manifest txt testa class   then we run jar file by this command   java -jar anyname jar  way 2    Let we have one package named one and every class are inside it  then we create jar file by this command       jar cf anyname jar one   then we open manifest txt inside directory META-INF in anyname jar file and write     Main-Class  one mainclassname    in third line   then we run jar file by this command       java -jar anyname jar   to make jar file having more than one class file   jar cf anyname jar one class two class three class

User · Answer

In order to create a  jar file  you need to use jar instead of java   jar cf myJar jar myClass class   Additionally  if you want to make it executable  you need to indicate an entry point  i e   a class with public static void main String   args   for your application  This is usually accomplished by creating a manifest file that contains the Main-Class header  e g   Main-Class  myClass     However  as Mark Peters pointed out  with JDK 6  you can use the e option to define the entry point   jar cfe myJar jar myClass myClass class    Finally  you can execute it   java -jar myJar jar   See also   Creating a JAR File Setting an Application s Entry Point with the JAR Tool

User · Answer

Often you need to put more into the manifest than what you get with the -e switch  and in that case  the syntax is   jar -cvfm myJar jar myManifest txt myApp class   Which reads   create verbose jarFilename manifestFilename   followed by the files you want to include   Note that the name of the manifest file you supply can be anything  as jar will automatically rename it and put it into the right place within the jar file

User · Answer

Sine you ve mentioned you re using Eclipse    Eclipse can create the JARs for you  so long as you ve run each class that has a main once   Right-click the project and click Export  then select  Runnable JAR file  under the Java folder   Select the class name in the launch configuration  choose a place to save the jar  and make a decision how to handle libraries if necessary   Click finish  wipe hands on pants

[java] Java creating .jar file

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