Need help to create a keystore.jks from my certificates

Hello, I have the files: cert.pem, chain.pem, fullchain.pem, privkey.pem and I need to create a keystore.jks from this files to use the certificates in a springboot java application. I try to use the gui keystore explorer. Can someone help me?

Thanks.

Mit freundlichen Grüßen,
Kevin Jedynak