The pair struck up a close friendship after performing together in Toronto in 2017 and Shawn says John has been a great help to him in his career.
He told PEOPLE: ''He's a badass. He's just so smart and intellectual. He has a very interesting view on the world -- a view I've never heard from anyone else.''
And Shawn, 19, loves that despite his career longevity, John, 40, is always aiming to better himself.
He said: ''He's one of my really, really good friends. The most incredible thing I learned from [him] is that no matter how much experience you have, you never are done learning; there's always something to be learned.
''John will send me new music and ask me what I think. When that happened to me the first time, I was so impressed that he didn't see himself as a master yet. He's always trying to learn and wants to get better; he always wants to grow with the people and not get left behind.
''He helped me with something on my new album. I'm sure we'll get together. Our friendship has just begun and there's a lot to happen in the future.''
And John recently called Shawn a ''better'' version of himself.
He said: ''Shawn's just a better version of me in a lot of ways. Shawn's like John Mayer 2.0, without the weird software viruses. He's a better version of a celebrity than I ever was. He's not as volatile.''
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