public class StringDemo{

     public static void main(String args[]){

         String str ="12343264sd6223";

         if (isNumber(str)){

             System.out.println("字符串由数字组成！");

         } else {

             System.out.println("字符串由非数字组成！");

         }

     }

     public static boolean isNumber(String temp) {

        char [] data = temp.toCharArray();

        for (int x= 0 ; x < data.length ; x ++ ){

            if (data [x] >'9' ||data [x] < '0'){

                return false ;//后续不再判断

            }

        }

        return true ;//如果全部验证通过返回true

     }

 }