从一种方法到另一种方法携带双变量

Question

删除以避免剽窃...

Answer 1

Your problem is that your local variable tax inside your method is shadowing the outer static tax variable.

So your code updates that "inner" tax; but not the outer.

Thus: simply remove all those

double tax = 0;

statements from the body of your method!

But: the better approach would be that your method returns that value. There is not much sense in using global variables to "communicate" values; when your method could simply return them! So change the method from "void" to "double", and simply return the computed value!

Plus: you duplicated those print statements for no reason. Just do one print in the end of the method! Seriously: whenever you have two pieces of code that do exactly the same thing ... get rid of the second one somehow!

And finally: never ever use special chars such as $ for variable/method/... names in your code!

Answer 2

double $$ = income - tax;//here tax is using your class static variable tax, which is never changed from 0.

To debug.. change your class variable to 1000 instead of 0 as a default value.

In your taxPayable() method dont declare double tax again. Just use the variable without declaring it

Answer 3

because you are re-declaring variable tax - please read about scopes. change each double tax = ... in your method taxPayable(int income) to just tax.