There are several websites that offer free Java courses online with a certificate of completion. Here are some options:
1. edX: edX offers a Java course in collaboration with Microsoft that covers basic programming concepts and teaches you how to write and debug Java programs. The course is free, but if you want to receive a certificate, you'll need to pay a fee.
2. Coursera: Coursera has several free Java courses, including an introductory course and a course on object-oriented programming. These courses are offered by universities and companies and come with a certificate of completion.
3. Codecademy: Codecademy offers a free Java course that covers basic programming concepts, data types, control flow, and functions. The course includes interactive lessons and quizzes, and you can earn a certificate of completion when you finish.
4. Udemy: Udemy has several free Java courses that cover topics such as Java programming for beginners, object-oriented programming in Java, and Java web development. These courses come with a certificate of completion.
5. SoloLearn: SoloLearn offers a free Java course that covers basic programming concepts, data types, operators, and control structures. The course includes interactive lessons and quizzes, and you can earn a certificate of completion when you finish.
These are just a few of the many options available for free Java courses with a certificate. Keep in mind that some of these courses may have paid upgrades or require payment for the certificate.