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javacompiler-errorsjavac

Classpath invalid flag - Java

I am using javac to compile a file called Rengine.jar.

I tried:

javac –classpath ./REngine.jar
javac –cp ./REngine.jar
javac ./REngine.jar
javac –classpath REngine.jar

And here are the errors that I got:

javac: invalid flag: –classpath
Usage: javac <options> <source files>
use -help for a list of possible options

javac: invalid flag: –cp
Usage: javac <options> <source files>
use -help for a list of possible options

javac: invalid flag: ./REngine.jar
Usage: javac <options> <source files>
use -help for a list of possible options

javac: invalid flag: –classpath
Usage: javac <options> <source files>
use -help for a list of possible options

I am not familiar with Java at all and I could not find an answer to this problem with a Google search. I precise that I am in the good directory and that I am using Mac OSX. My Java version is 1.8.0_20. Any advice would be much appreciated! :)

Solution

  • Firstly, you cannot compile a .jar file. A .jar file is a collection of complied .java files (.class files). You are however able to run a .jar file if your manifest file is set up correctly.

    The procedure is as follws:
    Compile: 

    javac MyClass.java

    the above line creates MyClass.class

    Create JAR with manifest file: 

    jar cfe myJar.jar myClass myClass.class

    Run JAR: 

    java -jar myJar.jar