I am currently working on mainframes application support. I am very much unsatisfied and I am interested in Java. I am learing Java apart from my daily office work.
Will I be able to switch to Java after 1 year of experince from my current profile? Please I require all your suggestions.
Maybe. It's a combination of luck (the right opportunity existing), your skills and knowledge and experience. With one year of experience (in something else), you will be applying for entry level Java jobs. Your job experience will probably be treated like people's internships. This is ok. Just start learning! Also, remember to practice coding and not just reading a book.
Finally, if you are applying for work in an English speaking country, note that it is "career" not "carrer". You want to make that mistake here and not in a typo on your cover letter.