Convert .p7b file to .pem
openssl pkcs7 -print_certs \ -in file.p7b \ -out file.pem
Export .pem with private key in .p12
openssl pkcs12 -export \ -name aliasName \ -in file.pem \ -inkey file.key \ -out file.p12
Import .p12 file in keystore
keytool -importkeystore \ -srcstoretype pkcs12 \ -srckeystore file.p12 \ -destkeystore file.jks
Panos Bariamis 
Helped me a lot! I couldn’t find other way to import both to keystrore. I spent many hours with this and finally this was the one which helped!! THANKS!