How i can train on java ?

Answer 1

https://www.codewars.com is a good place to train with many languages including Java ^^

Answer 2

start with the java course. buy a few books. I liked Head First Java personally. Check youtube. the coding train is a great YouTube channel. he uses javascript, but he is good and figuring out how to make his things work in java helps you learn

Also, as Visph said. Codewars is excellent practice as well

Answer 3

take a part time course somewhere in Java. Or crack it on your own by reading, watching tutorials and most importantly coding.