Here's an example Java program to check if a string is numeric:

public class NumericChecker {
    public static void main(String[] args) {
        String str = "12345";

        if (isNumeric(str)) {
            System.out.println("The string is numeric");
        } else {
            System.out.println("The string is not numeric");
        }
    }

    public static boolean isNumeric(String str) {
        try {
            Double.parseDouble(str);
            return true;
        } catch (NumberFormatException e) {
            return false;
        }
    }
}

This program uses an isNumeric method that takes a string as input and returns true if the string is numeric, and false otherwise.

To check if the string is numeric, the isNumeric method attempts to parse the string as a double using the Double.parseDouble method. If the parse operation succeeds, the method returns true, indicating that the string is numeric. If the parse operation throws a NumberFormatException, the method returns false, indicating that the string is not numeric.

In the main method, the isNumeric method is called with a sample string "12345". If the string is numeric, the program prints a message indicating that the string is numeric. Otherwise, it prints a message indicating that the string is not numeric.