如何从一个类到另一个类调用变量？

Question

For example, i have class a,b,c,d,e,f. and for class f, they have many variable, so how can I call class f variable when i am in class a,b,c,d,e? Use import? or use static variable? Can static variable change while programming? Thank you.

Answer 1

Multiple ways:

• Define variable as static, final and public if that value doesn't change and is a constant.

   public static final int DUMMY = 9999; 

And then you could access it like:

    System.out.println(F.DUMMY);

• Define that variable as instance variable and provide getter and setter in f class. Inject instance of f within a,b.. classes and use getter/setter

    public class F { private int dummy; //getter/setter } public class a { .. int value = f.getDummy(); } 

Answer 2

Can static variable change while programming?

Yes static fields can be changed later after declaring it.But only one value is maintained through out one instance of JVM.

No matter how many instance of class is created the static fileds within the class will be same for all the instance of class.

Here is good explaination in jls.

Static Fields Explaination