Do you have any professional software experience? Having a portfolio is nice but professional experience is better and makes the portfolio less necessary.

A Java certification will be helpful but only for jobs that use Java. Java is a popular language and if you enjoy it then I would say study for the certification, make a portfolio, and get certified. But certifications aren’t usually necessary or even very helpful for most web development jobs. Most web development jobs involve JavaScript, and to my knowledge there aren’t any JavaScript certifications that any company cares about.