/*
    GUI_IO1.java
    CIS 160
    David Klick
    2015-09-02

    Demonstrates simple GUI I/O.
    
    Note: Unexpected user input will crash this program.
*/

import javax.swing.JOptionPane;  // needed for JOptionPane

public class GUI_IO1 {
    public static void main(String[] args) {
        String name, strIn;
        int age;

        // Get name from user - easy since it is a String
        name = JOptionPane.showInputDialog("Please enter your name");

        // JOptionPane can get input, but it will be a String.
        // Get age from user - must convert from String to int
        strIn = JOptionPane.showInputDialog("Please enter your age");
        age = Integer.parseInt(strIn);

        // Display what was read in
        JOptionPane.showMessageDialog(null, "Your name is " + name);
        JOptionPane.showMessageDialog(null, "Your age is " + age);

        /*
            Please note that an object reference is required as the
            second argument to JOptionPane.showMessageDialog(). This
            is fine if you are displaying a String since Strings are
            objects, but the eight primitive data types (boolean,
            char, byte, short, int, long, float, double) are NOT
            objects. This means that you can NOT display them directly.
            In other words, this is NOT allowed:
               JOptionPane.showMessageDialog(null, age);

            If you do want to display just a number, use the following
            trick:
               JOptionPane.showMessageDialog(null, "" + age);

            The expression ["" + age] will have to be evaluated before
            sending the information to JOptionPane.showMessageDialog().
            Java will see you are using "+" with a number to a String.
            It knows it can't add a number to a String, but it can turn
            the number into a String of characters and append it to the 
            other String. Since the other String contains nothing, you
            have conveniently converted the number into a String. This
            String is then sent to JOptionPane.showMessageDialog().
        */

    }
}