Re-compile a Java Class from Jar

Question

I have an executable jar that has one class file with a wrong value. I requested that file from the author and corrected the value.

Now I want to compile it and add the compiled class file into the jar and run it.

Not surprisingly I get multiple "cannot find symbol" errors for references of custom object that were in the jar file.

I tried to compile the file by referencing the jar file in the classpath like so

C:/> javac  file.java  -classpath C:/folder/where/jar/is

but this doesnt seem to work... I get the same errors as if just doing

C:/> javac file.java

Is there a way to compile this individual class somehow referencing the other files in the jar?

Thanks.

---

Errors I am getting while following some of the suggestions below here:

javac -classpath C:/jar/location.jar File.java

File.java:226: cannot find symbol
symbol  : class Stuff
location: class com.shared.stuffers
                              Stuff s1 = new Stuff();
                                             ^

Stuff class is found in the Jar, but can not be seen by the javac program... I feel like I am doing something wrong but not sure where? Thanks.

Solution 1

You will want to compile your file like so:

javac -classpath C:\folder\where\jar\is\the_jar_file.jar file.java

per the javac usage instructions:

C:\Console2>javac -help
Usage: javac <options> <source files>

Solution 2

Once you've compiled the new file (such as in Mr. Will's answer), you can add the new file to the jar using:

jar uf C:\folder\where\jar\is\the_jar_file.jar file.class

Comments

[Admin]

Thanks for suggestion --- but issue remains :(

[mjn]

The base directory (.) is missing. Command should be javac -classpath .;C:\folder\where\jar\is\the_jar_file.jar file.java