Java Reference
In-Depth Information
Add
Subtract
Multiply
Divide
F IGURE 9.14 The program takes an expression in one argument ( operand1 operator
operand2 ) from the command line and displays the expression and the result of the
arithmetic operation.
The program is shown in Listing 9.5.
L ISTING 9.5 Calculator.java
1 public class Calculator {
2 /** Main method */
3 public static void main(String[] args) {
4 // Check number of strings passed
5 if ( != 1 ) {
6 System.out.println(
7 "Usage: java Calculator \"operand1 operator operand2\"" );
8 System.exit( 1 );
9 }
10
11
args.length
check argument
// The result of the operation
12
int result = 0 ;
13
14 // The result of the operation
15 String[] tokens = args[ 0 ].split( " " );
16
17
split string
// Determine the operator
check operator
18
switch (
tokens[ 1 ].charAt( 0 )
) {
19
case '+' : result = Integer.parseInt(
tokens[ 0 ]
) +
20 Integer.parseInt(
tokens[ 2 ]
);
21
break ;
22
case '-' : result = Integer.parseInt(
tokens[ 0 ]
) -
23 Integer.parseInt(
tokens[ 2 ]
);
24
break ;
25
case '*' : result = Integer.parseInt(
tokens[ 0 ]
) *
26 Integer.parseInt(
tokens[ 2 ]
);
27
break ;
28
case '/' : result = Integer.parseInt(
tokens[ 0 ]
) /
29 Integer.parseInt(
tokens[ 2 ]
);
30 }
31
32 // Display result
33 System.out.println(
tokens[ 0 ]
+ ' ' +
tokens[ 1 ]
+ ' '
34 +
tokens[ 2 ]
+ " = " + result);
35 }
36 }
Search WWH ::




Custom Search