Thread: GUI Calculator: Adding Answer Button? Please Help

outside the if statements, it has no value.

No, the answer variable will have a value anywhere in the method. It will default to zero and then can be changed anywhere by an assignment statement.
Add printlns to show its value before and after all the if statements where it has a value assigned to it.

public void aMethod() {
  int aMethodVar = 0;  // define this variable at the method level
  System.out.println("1aMethodVar=" + aMethodVar);  // show its value here
  if (cond) {
     int x = 0;  // define this variable inside of the if{} it goes away at the ending }
 
     // aMethodVar is known here
    aMethodVar = 234;  // change the value
  } // end of if x is now gone
  System.out.println("2aMethodVar=" + aMethodVar);  // show its value here 
  int anotherVar = 33; // define this variable at the method level
 
  if(cond2) {
     // anotherVar and aMethodVar are known here. x is NOT known
    aMethodVar = 432;  // change the value
  }
} // end aMethod()
 System.out.println("3aMethodVar=" + aMethodVar);  // show its value here

I still don't understand how the println's make a difference

They don't effect how your code executes.
The printlns are for debugging. To show you what the values of variables are as the code executes.