1. Message, Input, and Confirm Dialogs
JOptionPane
JOptionPane Dialogs
January 17, 2019

2. Dialog Boxes Message, Input, and Confirm Dialogs JOptionPane Dialogs
January 17, 2019

3. Dialog Boxes
A dialog box is a small graphical window that displays a message to the user or requests input
A variety of simple dialog boxes can be displayed using the JOptionPane class
Message Dialog - a dialog box that displays a message
Input Dialog - a dialog box that prompts the user for typed input
Confirm Dialog This is a dialog box that asks the user a Yes/No question
JOptionPane Dialogs
January 17, 2019

4. Dialog Boxes
The JOptionPane class provides static methods to display each type of dialog box
JOptionPane Dialogs
January 17, 2019

5. Message dialogs
JOptionPane Dialogs
January 17, 2019

6. Message Dialogs
JOptionPane.showMessageDialog(null, "Hello World");
The first argument can be a reference to a graphical component such as another window
The dialog box is displayed centered on that component
If null is passed as the first argument, the dialog box to be displayed in the center of the screen
The second argument is the message that is to be displayed
JOptionPane Dialogs
January 17, 2019

7. Last parameter determines which icon is shown here
Message Dialogs
By default the dialog box has:
the string “Message” displayed in its title bar, and
an information icon (showing the letter “i”) is displayed
JOptionPane.showMessageDialog(null,
"Invalid Data",
"My Message Box",
JOptionPane.ERROR_MESSAGE);
The third parameter is the title bar text
Last parameter determines which icon is shown here
JOptionPane Dialogs
January 17, 2019

8. Message Dialogs
These constants can be used to control the icon that is displayed
JOptionPane.ERROR_MESSAGE
JOptionPane.INFORMATION_MESSAGE
JOptionPane.WARNING_MESSAGE
JOptionPane.QUESTION_MESSAGE
JOptionPane.PLAIN_MESSAGE
JOptionPane Dialogs
January 17, 2019

9. Message Dialogs with Icons
JOptionPane Dialogs
January 17, 2019

10. Message Dialogs
The dialog boxes displayed by the JOptionPane class are modal dialog boxes
A modal dialog box suspends execution of any other instructions in your program until the dialog box is closed
When the JOptionPane.showMessageDialog method is called, the instructions after the method call do not execute until the user closes the message box
JOptionPane Dialogs
January 17, 2019

11. Input Dialog
JOptionPane Dialogs
January 17, 2019

12. Input Dialogs
An input dialog is a quick and simple way to ask the user to enter String data
The dialog displays a text field, an OK button and a Cancel button
If OK is pressed, the dialog returns the user’s input
If Cancel is pressed, the dialog returns null
JOptionPane Dialogs
January 17, 2019

13. Input Dialogs
The JOptionPane has several overloaded versions of the static showInputDialog method
Here are two of them:
showInputDialog(Object message)
showInputDialog(Component parent,
Object message,
String title,
int messageType)
JOptionPane Dialogs
January 17, 2019

14. Input Dialogs
String name;
name = JOptionPane.showInputDialog("Enter your name.");
The argument passed to the method is the message to display
If the user clicks on the OK button, name references the string entered by the user
If the user clicks on the Cancel button, name references null
JOptionPane Dialogs
January 17, 2019

15. Input Dialogs By default, the input dialog box:
has the string “Input” in its title bar, and
displays a question icon
String value;
value = JOptionPane.showInputDialog (null,
"Enter the value again.",
"Enter Carefully!",
JOptionPane.WARNING_MESSAGE);
JOptionPane Dialogs
January 17, 2019

16. Input Dialog with Default Value
Occasionally with an Input Dialog, a particular value is entered frequently
In that case, that value can be used as a default value the user can accept or replace
The calling sequence in this case is
JOptionPane.showInputDialog (message, defaultValue)
Example:
JOptionPane Dialogs
January 17, 2019

17. Numeric Data Type Wrappers
The Input Dialog inputs only string data. If one inputs a number, it must be converted from the string received into a number before it can be used in numeric calculations
Java provides wrapper classes for all primitive data types
The numeric primitive wrapper classes are:
Wrapper Class
Numeric Primitive Type It Applies To
Byte
byte
Double
double
Float
float
Integer
int
Long
long
Short
short
JOptionPane Dialogs
January 17, 2019

18. The Parse Methods
A string containing a number, such as “127.89”, can be converted to a numeric data type
Each of the numeric wrapper classes has a static method that converts a string to a number
The Integer class has a method that converts a String to an int
The Double class has a method that converts a String to a double
The other numeric wrapper classes have similar methods
These methods are known as parse methods because their names begin with the word “parse”
JOptionPane Dialogs
January 17, 2019

19. The Parse Methods: Examples
// Store 1 in bVar
byte bVar = Byte.parseByte("1");
// Store 2599 in iVar
int iVar = Integer.parseInt("2599");
// Store 10 in sVar
short sVar = Short.parseShort("10");
// Store in longVar
long longVar = Long.parseLong("15908");
// Store 12.3 in fVar
float fVar = Float.parseFloat("12.3");
// Store in dVar
double dVar = Double.parseDouble("7945.6");
The parse methods all throw a NumberFormatException if the String argument does not represent a numeric value
JOptionPane Dialogs
January 17, 2019

20. Now, one can use hours and sales in calculations
“Parse” examples
Now, one can use hours and sales in calculations
JOptionPane Dialogs
January 17, 2019

21. Confirm dialog
JOptionPane Dialogs
January 17, 2019

22. Confirm Dialog
A confirm dialog box typically asks the user a yes or no question
By default Yes, No, and Cancel buttons are displayed
The showConfirmDialog method is used to display a confirm dialog box
There are several overloaded versions of this method
int showConfirmDialog(Component parent, Object message)
int showConfirmDialog(Component parent, Object message, String title, int optionType)
JOptionPane Dialogs
January 17, 2019

23. Confirm Dialog By default the confirm dialog box displays:
int value;
value = JOptionPane.showConfirmDialog (null, "Are you sure?");
By default the confirm dialog box displays:
“Select an Option” in its title bar
Yes, No, and Cancel buttons
JOptionPane Dialogs
January 17, 2019

24. Confirm Dialog
The showConfirmDialog method returns an integer that represents the button clicked by the user
The button that was clicked is determined by comparing the method’s return value to one of the following constants:
JOptionPane.YES_OPTION
JOptionPane.NO_OPTION
JOptionPane.CANCEL_OPTION
JOptionPane Dialogs
January 17, 2019

25. Confirm Dialog int value; value = JOptionPane.showConfirmDialog (null,
"Are you sure?");
if (value == JOptionPane.YES_OPTION) {
// If the user clicked Yes, this code is executed }
else if (value == JOptionPane.NO_OPTION)
// If the user clicked No, this code is executed
else if (value == JOptionPane.CANCEL_OPTION)
// If the user clicked Cancel, this code is executed
JOptionPane Dialogs
January 17, 2019

26. Confirm Dialog
int value;
value = JOptionPane.showConfirmDialog(null,
"Are you sure?",
"Please Confirm", JOptionPane.YES_NO_OPTION);
One of the following constants can be used for the fourth parameter to control which buttons appear in the Confirm dialog
JOptionPane.YES_NO_OPTION
JOptionPane.YES_NO_CANCEL_OPTION
Example: TestAverageDialog.java
JOptionPane Dialogs
January 17, 2019