CODEWITHSUNDEEP
javaregex
Jack
Jack

Reputation: 763

Check if string contains any non digit character - no libraries - Java

This might be clear to someone familiar with regex expressions but I am not.

Example:

String onlyNumbers = "1233444";
String numbersAndDigits = "123344FF";

if (IS_ONLY_NUMBERS(onlyNumbers))
    return true;

if (IS_ONLY_NUMBERS(numbersAndDigits))
    return false;

Suggestions? Is there a way to do a similar check without importing libraries?

Upvotes: 3

Views: 3745

Answers (2)

Konstantin Yovkov
Konstantin Yovkov

Reputation: 62864

You can try with:

if (onlynumbers.matches("[0-9]+")
    return true;

if (numbersanddigits.matches("[0-9]+")
    return false;

Also, as a shortcut, you can use \\d+ instead of [0-9]+. It's just a matter of choice which one to pick.

Upvotes: 2

Tetramputechture
Tetramputechture

Reputation: 2921

Try using String.matches("\\d+"). If that statement returns false, then there are characters in your string that are not digits. \d means the character must be a digit, and the + means that every character must be a digit.

Like so:

String onlynumbers = "1233444";
String numbersanddigits = "123344FF";

System.out.println(onlynumbers.matches("\\d+")); // prints "true"
System.out.println(numbersanddigits.matches("\\d+")); // prints "false"

Upvotes: 4

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