If you have more than one one crt files, merge them to single abc.crt
openssl pkcs12 -export -in abc.crt -inkey abc.key -out abc.p12
keytool -importkeystore -srckeystore abc.p12 \
-srcstoretype PKCS12 \
-destkeystore abc.jks \
-deststoretype JKS
default alias is 1
password is what you set at the prompt