How can I check if a string contains only numbers?
For example, you can not have * / = e etc ... only numbers.
Because I need to convert a string to int and if you type letters, symbols will generate an error.
Verify that the string contains only numbers
-3
asked by anonymous 15.12.2017 / 19:47
2 answers
4
One of the ways to know if the string contains only numbers is to use a regular expression
"1239417".matches("[0-9]+"); // true
"12312a".matches("[0-9]+"); // false
"12312+".matches("[0-9]+"); // false
In the regular expression [0-9]+
-
[and]: delimits a set of characters -
0-9: the set of characters, any one between 0 and 9 -
+: of the defined expression, must match 1 or more groups
15.12.2017 / 20:00
2
Another way is to try converting to integer:
String input = "123s";
try {
Integer.valueOf(input);
} catch (Exception e) {
System.out.println("Número inválido");
}
21.12.2017 / 06:37