Java String是Numeric

import java.util.Scanner;

public class StringNumeric {

   public static void main(String[] args) {

      Scanner sc = new Scanner(System.in);

      System.out.println("Enter a string ::");

      String str = sc.next();

      boolean number = str.matches("-?\\d+(\\.\\d+)?");



      if(number){

         System.out.println("Given string is a number");

      } else {

         System.out.println("Given string is not a number");

      }

   }

}