You can find information about how to setup development environment for Java or for C++ here.
maven -o clean new
svn diff File >> patchfile
Please try to give your patch files meaningful names. This helps the developer who applies a number of different patches. A recommendation is to use the JIRA issue number as part of patch file name. For example
svn diff File >> File312
In this example, the number 312 is a JIRA issue number associated with this patch.
Please include detailed steps to reproduce the problem in the issue description so that the patch can be properly verified after it is applied.