Java visibility modifier and parameter passing

Java visibility modifier:

Public, private, protect

(1) Before classes, methods, and data fields, use public to indicate that they can be accessed by any other class.

(2) without any modification, the data domain and method can be accessed by any class in the same package.

(3) Before the class, add public to indicate that the class can be accessed by any other class. If not, the class can be accessed by other classes in the same package.

(4) The methods and data fields of the private modifier can be accessed in their own classes.

Parameter transfer:

In Java, basic data is passed as values, and other data is passed as references, that is, the address of the variable. Therefore, it can be considered that it is a value that does not consume extra space.