How do you check if a string contains numbers?

To find whether a given string contains a number, convert it to a character array and find whether each character in the array is a digit using the isDigit() method of the Character class .

To match any number from 0 to 9 we use \d in regex . It will match any single digit number from 0 to 9. \d means [0-9] or match any number from 0 to 9. Instead of writing 0123456789 the shorthand version is [0-9] where [] is used for character range.

The [0-9] expression is used to find any character between the brackets . The digits inside the brackets can be any numbers or span of numbers from 0 to 9. Tip: Use the [^0-9] expression to find any character that is NOT a digit.

Using Regular Expression: