There are different scenarios for converting code signing certificates, these are the most common. If your scenario is not listed here, refer to your manufacturer's instructions.
SPCfile into the Windows certificate store on the same machine (using the same login account) where the certificate request was submitted.
SPCfile in the Windows Explorer and select Install Certificate. Proceed through the wizard as directed.
SPCfile, you will need to change the file type filter. When you're finished, click OK.
PFX/P12file, including the private key and all intermediate certificates in the chain. For more information see Export an Installed Code Signing Certificate from Windows.
See Sign Java code.