1. Dialog Boxes

2. JOptionPane Class Allows you to display a dialog box
Small graphical window that displays a message to the user or requests input
Types:
Message Dialog
Input Dialog
Need to import javax.swing.JOptionPane

3. Displaying Message Dialogs
showMessaegDialog method – used to display a message dialog
JOptionPane.showMessageDialog(null, “Hello World”);
First argument will be discussed when we learn about Graphical User Interfaces (GUIs) – used to display other graphical windows
Second argument is the message that we wish to display

4. Displaying Input Dialogs
Quick and easy way to enter data
String name;
name = JOptionPane.showInputDialog(“Enter your name.”);

5. Ending Program Need: System.exit(0);
When using the JOptionPane class, you must end a program
Does not automatically stop executing when the end of the main method is reached because the class causes an additional task(thread) to run
Need: System.exit(0);
Needs an integer argument - value 0 traditionally indicates that the program ended successfully

6. Converting String Input to Numbers
Unlike the Scanner class, the JOptionPane class does not have different methods for reading values of different data types as input
showMessaegDialog method always returns the user’s input as a String, even if a numeric value was entered
What is the problem with this?

7. Converting String Input to Numbers
Use methods to convert string value to a numeric value
Method
Example Code
Double.parseDouble
double num;
num = Double.parseDouble(str)
Integer.parseInt
int num;
num = Integer.parseInt(str)

8. Example *Now you could use number to perform math methods* int number;
String str;
str = JOptionPane.showInputDialog(“Enter a number.”)
number = Integer.parseInt(str);
*Now you could use number to perform math methods*