java coding

3. Write a Java program that will read a String using a JoptionPane, count the number of characters that are digits, and display that number in another JOptionPane. This may make use of the method in the character wrapper class called isDigit. 4. Write a class called Question4Book that contains the following information: 1. Instance variables for the title (String), author (String) and price (float) of the book. 2. A three-argument constructor to set each of the instance variable above. If the title or author is null or the price is less than 0, throw an IllegalArgumentException stating the argument that is not correct. 3. Get and Set methods for each variable. public class Question 4Book {