(NumberFormatException) Listing 1, Calculator.java, is a simple commandline calculator. No...

(NumberFormatException) Listing 1, Calculator.java, is a simple commandline calculator. Note that the program terminates if any operand is nonnumeric. Write a program with an exception handler that deals with nonnumeric operands; then write another program without using an exception handler to achieve the same objective. Your program should display a message that informs the user of the wrong operand type before exiting (see Figure 1).

FIGURE 1 The program performs arithmetic operations and detects input errors.

LISTING 1 Calculator.java

1 public class Calculator {
2 /** Main method */
3 public static void main(String[] args) {
4 // Check number of strings passed
5 if (args.length != 3) {
6 System.out.println(
7 "Usage: java Calculator operand1 operator operand2");
8 System.exit(0);
9 }
10
11 // The result of the operation
12 int result = 0;
13
14 // Determine the operator
15 switch (args[1].charAt(0)) {
16 case '+': result = Integer.parseInt(args[0]) +
17 Integer.parseInt(args[2]);
18 break;
19 case '-': result = Integer.parseInt(args[0]) -
20 Integer.parseInt(args[2]);
21 break;
22 case '.': result = Integer.parseInt(args[0]) *
23 Integer.parseInt(args[2]);
24 break;
25 case '/': result = Integer.parseInt(args[0]) /
26 Integer.parseInt(args[2]);
27 }
28
29 // Display result
30 System.out.println(args[0] + ' ' + args[1] + ' ' + args[2]
31 + " = " + result);
32 }
33 }