Hello Sir/Ma'am. Java is a general-purpose computer-programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" meaning that compiled Java code can run on all platforms that support Java without the need for recompilation. The best places to do a certified JAVA course are : HP Education Services, NIIT, udemy, coursera and edX. After doing the course you can also opt for the Oracle Certified examination of JAVA.