The following code is not robust against invalid user input. Describe how to change the code so that it will not proceed until the user has entered a valid age and grade point average (GPA). Assume that any int is a legal age and that any double is a legal GPA.

Scanner console = new Scanner(System.in);
System.out.print("Type your age: ");
int age = console.nextInt();
System.out.print("Type your GPA: ");
double gpa = console.nextDouble();
For an added challenge, modify the code so that it rejects invalid ages (for example, numbers less than 0) and GPAs (say, numbers less than 0.0 or greater than 4.0).