What's mean oop ???

Question

learning java

Answer 1

Object Oriented Programming

[ https://www.google.com/ ]

Answer 2

Your question had been asked many times before, you should always check if there isn't an answer in Q&A already.
Check this other questions for instance 😉

https://www.sololearn.com/discuss/455677/?ref=app

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https://www.sololearn.com/discuss/383976/?ref=app