Check and extract a number from a String in Java

I'm writing a program where the user enters a String in the following format:

"What is the square of 10?"

1. I need to check that there is a number in the String
2. and then extract just the number.
3. If i use .contains("\\d+") or .contains("[0-9]+"), the program can't find a number in the String, no matter what the input is, but .matches("\\d+")will only work when there is only numbers.

What can I use as a solution for finding and extracting?

try this

str.matches(".*\\d.*");

If you want to extract the first number out of the input string, you can do-

public static String extractNumber(final String str) {                
    
    if(str == null || str.isEmpty()) return "";
    
    StringBuilder sb = new StringBuilder();
    boolean found = false;
    for(char c : str.toCharArray()){
        if(Character.isDigit(c)){
            sb.append(c);
            found = true;
        } else if(found){
            // If we already found a digit before and this char is not a digit, stop looping
            break;                
        }
    }
    
    return sb.toString();
}

Examples:

For input "123abc", the method above will return 123.

For "abc1000def", 1000.

For "555abc45", 555.

For "abc", will return an empty string.

I think it is faster than regex .

public final boolean containsDigit(String s) {
    boolean containsDigit = false;

    if (s != null && !s.isEmpty()) {
        for (char c : s.toCharArray()) {
            if (containsDigit = Character.isDigit(c)) {
                break;
            }
        }
    }

    return containsDigit;
}