Does Berkeley believe that objects go out of existence when nobody is perceiving them? If not, what does he believe?

No. Berkeley believed that a belief that something exists is justified if and only if the object at issue can be perceived by someone or something, and if so, then the object must be just a collection of ideas; ideas that we all collectively perceive to be true and real. Therefore, we must accept the fact that there are no material objects and just a collection of ideas, which made Berkeley an immaterialist. According to …showed first 75 words of 224 total…

…showed last 75 words of 224 total…although I no longer see the tree, it continues to exist so long as someone else is perceiving it. Something that is imaginary exists in one person's mind alone and continues to exist only if the person continues to thinks of it. But if something exists in many minds, it can continue to exist whether I perceive it or not. However, once nobody perceives the idea of an object's existence, the object ceases to exist.