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http://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html
http://leepoint.net/notes-java/data/variables/45local-inst-class.html
- Instance Variables (Non-Static Fields) Technically speaking, objects store their individual states in "non-static fields", that is, fields declared without the
statickeyword. Non-static fields are also known as instance variables because their values are unique to each instance of a class (to each object, in other words); thecurrentSpeedof one bicycle is independent from thecurrentSpeedof another. - Class Variables (Static Fields) A class variable is any field declared with the
staticmodifier; this tells the compiler that there is exactly one copy of this variable in existence, regardless of how many times the class has been instantiated. A field defining the number of gears for a particular kind of bicycle could be marked asstaticsince conceptually the same number of gears will apply to all instances. The codestatic int numGears = 6;would create such a static field. Additionally, the keywordfinalcould be added to indicate that the number of gears will never change. - Local Variables Similar to how an object stores its state in fields, a method will often store its temporary state in local variables. The syntax for declaring a local variable is similar to declaring a field (for example,
int count = 0;). There is no special keyword designating a variable as local; that determination comes entirely from the location in which the variable is declared — which is between the opening and closing braces of a method. As such, local variables are only visible to the methods in which they are declared; they are not accessible from the rest of the class. - Parameters You've already seen examples of parameters, both in the
Bicycleclass and in themainmethod of the "Hello World!" application. Recall that the signature for themainmethod ispublic static void main(String[] args). Here, theargsvariable is the parameter to this method. The important thing to remember is that parameters are always classified as "variables" not "fields". This applies to other parameter-accepting constructs as well (such as constructors and exception handlers) that you'll learn about later in the tutorial.
전역변수, 멤버변수, 로컬변수 등 다양한 이름의 변수들이 존재한다. 물론 의미만 통하면 개발자들 끼리 큰 문제는 없겠지만 정확한 명칭은 위와 같습니다. (Oracle Refrence 자료)
'인스턴스 변수'는 Static 이 아닌 변수를 의미합니다.
'클래스 변수'는 Static 으로 선언한 변수를 의미합니다.
'로컬 Variable' 변수는 method 안에서만 처리 되는 등 지역변수를 의미합니다. (쓰고 버려지는 변수를 의미합니다.)
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