Why does one class not see the variables of another?

Question

Java

I am learning on the well-known JAVA site and I don’t understand why MainActivity doesn’t see the variables from Question.java
I know that the question is stupid, but I don’t understand myself (

Answer 1

Because:
1. A class is not just a file in which the code is written. Until you have created an object (an instance of a class), it does not exist, as well as its variables (with the exception of static variables).
2. To access variables of another class, you must access them through this class, for example:

Question question = new Question();
....
public boolean isCorrect(Question quest) {
    return quest.correctAnswer == quest.playerAnswer;
}

3. Thirdly, in your case, you should not write at all as you wrote, or as I showed in paragraph 2, the isCorrect method should be a method of the Question class and be called as: quest.isCorrect ()
And if it seemed to you that I answered better than Sergey Gornostaev , then you are mistaken. He is completely right, read the tutorials, and on that site you can consolidate your knowledge, although even for this your own pet project is better.

Answer 2

Because you teach Java on a well-known site, and not from a textbook.