getting part of a number string

lets say i have a number string "1234567890" and out of that i want to get the first 3 digits from the number string "123". everything i have looked at needs some sort of pattern to split a string but the number could be any number so ther开发者_运维问答e would not be any pattern but i need the first 3 digits of the number.

can this be done?

You need the substring method on String. See http://download.oracle.com/javase/6/docs/api/java/lang/String.html#substring%28int,%20int%29 for details.

String firstThreeDigits = number.substring(0, 3);

Seems like you could just use a substring:

number.substring(0, 3);

String myFirstThreeDigitsAsStr = String.valueOf(mynumber).substring(0,3)

"1234567890".substring(0, 3); is what you need. That method returns a String that starts at the 0th index of your input and ends at index 3.

If the string contains a number, like your example you can simply use the substring method:

String number = "12345678";
String firstThreeDigits = number.substring(0, 3);

If you mean you need grab the first number out of a String and get the first 3 characters you could do this:

public class NumberFinder {

    public int findNumber(String string) throws NumberFormatException{
        String regex = "\\d+"; //matches one or more digits
        Pattern myPattern = Pattern.compile(regex);
        Matcher myMatcher = myPattern.matcher(string);
        String numString = new String();
        while (myMatcher.find()) {
            numString = myMatcher.group(); //returns whole match
        }
        String numSub = numString.length() >= 3 ? numString.substring(0, 3).toString() : "Not Enough Numbers";
        System.out.println(string);
        System.out.println(numString);
        System.out.println(numSub);
        return Integer.parseInt(numSub);
    }
}

    public static void main(String[] args) {
        String string = "ABCD1242DBG";
        try {
            new NumberFinder().findNumber(string);
        } catch (NumberFormatException e) {
            System.out.println("Not enough numbers in " + string);
        }
    }