differentiating inputs by user in JOptionPane

Question

I want to write a program in which a box is shown to user and asks to enter a name.

If the name is typed correctly (real name), final message comes up but if for instance the user types an integer, the program asks the user to type a real name in String again.

Code :

import javax.swing.*;

public class Project018 {
    public static void main(String[] args) {

    String name = JOptionPane.showInputDialog("What is your name?");

    try {

    int number = Integer.parseInt(name);

        } catch (NumberFormatException n){

             JOptionPane.showMessageDialog(null, "Dear " + name + "\nwelcome to java programming course");
        } 


    String message = String.format("your name must not contain any number");

        JOptionPane.showMessageDialog(null, message);
    }

}

I want to know how I can loop back the program to the top when the user types an integer and how I can skip the second message when a real name is entered

Answer 1

I want to know how I can loop back the program to the top when the user types an integer

Well, for this I would use a do-while loop.

For checking if the input is / has numbers, you shouldn't do it trying to parse the numbers to integer. Instead I would use a Pattern with a Matcher and regex. Otherwise you're not considering this case: Foo123

In this case something like: [0-9]+ for the regex, and if the Matcher matches with it, then it has a number.

how I can skip the second message when a real name is entered

Based on if the Matcher matches something you show one dialog or the other

For example:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;

public class LoopingJOptionPane {
    private static final String REGEX = "[0-9]+";

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new LoopingJOptionPane()::createAndShowGui);
    }

    private void createAndShowGui() {
        boolean found = true;
        do { //This repeats this code if input is incorrect
            Pattern pattern = Pattern.compile(REGEX);

            String name = JOptionPane.showInputDialog("Enter your name");
            Matcher matcher = pattern.matcher(name); //We try to find if there's a number in our string

            found = matcher.find();

            if (found) { //If there's a number, show this message
                JOptionPane.showMessageDialog(null, "Please write only letters");
            } else { //Otherwise show this one
                JOptionPane.showMessageDialog(null, "Welcome " + name);
            }
        } while (found); //If it has no numbers, don't repeat
    }
}