JAVA

check have string have just numbers

String numbers = "6969696969";
boolean check_n = numbers.matches("[0-9]+"); // true

String notNumber = "0123meowGOGO88l";
boolean check_s = notNumber.matches("[0-9]+"); // false

check if the given string is a number

//Add this to your code and call
static private boolean isMyNumber(String s){
        try{
            Integer.parseInt(s);
            return true;
        }catch (Exception e){
            return false;
        }
    }