2022 Java Developer Roadmap. So how long does it take to become a Java developer? Does it take ten months, ten weeks or a day? You may find odd and unspecific answers to the question on online forums. As it entirely depends on the learning capacity of an individual. But, it will not take more than 3 months to 12 months for a person to learn Java. Here you will find the list of technologies, tools and libraries that you might adapt to become a Java developer. Using which you will be able to know why you choose one tool over another.