java check if string only contains numbers using regex

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import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Example {

    public static void main(String[] args) {
        String numbers = "1234";
        String text = "ABC";

        String regex = "^[0-9]+$";  // regex to check if string contains only digits
        Pattern pattern = Pattern.compile(regex);  // compiles the regex

        // find match between given string and pattern
        Matcher matcherNumbers = pattern.matcher(numbers);
        Matcher matcherText = pattern.matcher(text);

        // return true if the string matched the regex
        Boolean numbersMatches = matcherNumbers.matches();
        Boolean textMatches = matcherText.matches();

        System.out.println(numbersMatches); // true
        System.out.println(textMatches);    // false
    }
}