public class Test {
     /**
     * 判断一个字符串是否是数字。
     *
     * @param string
     * @return
     */
    public static boolean isNumber(String string) {
        if (string == null)
            return false;
        Pattern pattern = Pattern.compile("^-?\\d+(\\.\\d+)?$");
        return pattern.matcher(string).matches();
    }

    private static void isNumberTest() {
        System.out.println(isNumber("580"));
        System.out.println(isNumber("5234254125424584"));
        System.out.println(isNumber("dfg15s4df5sd1fds"));
    }

    public static void main(String[] args) {
        isNumberTest();
    }

}

Pattern p = Pattern.compile("(\\d{4}\\-\\d{1,2}\\-\\d{1,2})+");
Matcher m = p.matcher(testStr);
if(!m.find())
{
    testStr = "2000-01-01"
}