Chapter 17, Problem 3PP

Design and code a Swing GUI calculator. You can use Display 17.19 as a starting point, but your calculator will be more sophisticated. Your calculator will have two text fields that the user cannot change: One labeled "Result" will contain the result of performing the operation, and the other labeled "Operand" will be for the user to enter a number to be added, subtracted, and so forth from the result. The user enters the number for the "Operand" text field by clicking buttons labeled with the digits o through 9 and a decimal point, just as in a real calculator. Allow the operations of addition, subtraction, multiplication, and division. Use a GridLayout manager to produce a button pad that looks similar to the keyboard on a real calculator.

When the user clicks a button for an operation, the following occurs: the operation is performed, the "Result" text field is updated, and the "Operand" text field is cleared. Include a button labeled "Reset" that resets the "Result" to 0.0. Also include a button labeled "Clear" that resets the "Operand" text field so it is blank.

number in the "Operand" text field. Because values of type double are, in effect, approximate values, it makes no sense to test for equality with 0.0. Consider an operand to be "equal to zero" if it is in the range $-1.0\text{e}-10\text{to}+1.0\text{e}-\text{10}\text{.}$