문자열이 숫자인지 확인하는 법

double.parseInt() & try-catch 활용

public static boolean isNumeric(String str) {
    if (str == null) {
        return false;
    }
    try {
        double d = Double.parseDouble(str);
    } catch (NumberFormatException nfe) {
        return false;
    }
    return true;
}

정규식 활용

private Pattern pattern = Pattern.compile("-?\\d+(\\.\\d+)?");

public boolean isNumeric(String strNum) {
    if (strNum == null) {
        return false; 
    }
    return pattern.matcher(strNum).matches();
}