Check if string contains valid number example.

1. /*
2. Check if string contains valid number example.
3. This example shows how to check if string contains valid number
4. or not using parseDouble and parseInteger methods of
5. Double and Integer wrapper classes.
6. */
7.  
8. public class CheckValidNumberExample {
9.  
10. public static void main(String[] args) {
11.  
12. String[] str = new String[]{"10.20", "123456", "12.invalid"};
13.  
14. for(int i=0 ; i < str.length ; i ++)
15. {
16.  
17. if( str[i].indexOf(".") > 0 )
18. {
19.  
20. try
21. {
22. /*
23. * To check if the number is valid decimal number, use
24. * double parseDouble(String str) method of
25. * Double wrapper class.
26. *
27. * This method throws NumberFormatException if the
28. * argument string is not a valid decimal number.
29. */
30. Double.parseDouble(str[i]);
31. System.out.println(str[i] + " is a valid decimal number");
32. }
33. catch(NumberFormatException nme)
34. {
35. System.out.println(str[i] + " is not a valid decimal number");
36. }
37.  
38. }
39. else
40. {
41. try
42. {
43. /*
44. * To check if the number is valid integer number, use
45. * int parseInt(String str) method of
46. * Integer wrapper class.
47. *
48. * This method throws NumberFormatException if the
49. * argument string is not a valid integer number.
50. */
51.  
52. Integer.parseInt(str[i]);
53. System.out.println(str[i] + " is valid integer number");
54. }
55. catch(NumberFormatException nme)
56. {
57. System.out.println(str[i] + " is not a valid integer number");
58. }
59. }
60. }
61.  
62. }
63. }
64.  
65. /*
66. Output would be
67. 10.20 is a valid decimal number
68. 123456 is valid integer number
69. 12.invalid is not a valid decimal number
70. */