Write a Java program that simulates a very simple, but unconventional, calculator. The applications GUI should include two text fields F1 and F2 for numerical input and a label for output. So, to compute 23 + 56, a user enters 23 into F1 and 56 into F2. There should be four buttons labeled +, ?, * , and /. When button B is pressed, the operation (F1) B (F2) is computed and the result displayed on the label. If a button is pressed and a field F1 or F2 is empty then the program should display an error message. Include a button that copies the result of the computation to F1 and another that copies the result to F2. These buttons facilitate subsequent computation using the result of the previous computation. A Quit button ends the program.