Re: Beginner question referring to an object in a class from within method in that class

Thanks Barbara. Between you, Craig Pelkie, and robmorning, I'm beginning to get it.

If I define it within MyClass, it's similar to a module-level field in RPG.

If I define it within the main() method, it's similar to a procedure-level field in RPG.

If I define it within an IF  statement, it's not the same as anything in RPG.

The other thing, I'm not certain of this yet, is what constitutes defining a field/variable?  At the moment, it looks like specifying the type ahead of the field/variable name means I'm defining/declaring it, and if I leave off the type, I'm using whatever version of the field/variable was defined in the closest scope.

Also, a variable can be defined with the "new" keyword, e.g.

    wb = new SXSSFWorkbook();

without specifying the type, since the type is determined by the method's constructor method.


On 7/28/2023 2:55 PM, Barbara Morris wrote:

On 2023-07-27 6:56 p.m., Peter Dow wrote:

I'm very much a beginner with Java and I'm having a problem understanding how scope works.
...

If you define a variable inside a block, it's only visible within that block.

Here, my variable "str" can't even be used in main() outside the "if" block where I defined it.

class MyClass
{
   static public void main()
   {
      if (1 == 2)
      {
         String str = "abc"; // only visible in this "if" block
         str = "def";        // ok, still in the "if" block
      }
      str = "ghi";           // str is not visible any more
   }
}