Posted 25 September 2009 - 05:33 PM
JRadio Button
Radio button allows user to select only one radio button in each group at a time. If a radio button is selected, whatever the previous radio button is, it will be deselected. To work with radio buttons, we need two classes. First, we create the radio buttons with the JRadioButton class, whose constructors and methods are at the link below
"Swing Method & Constructor Table ." Then we create a group for the buttons with the ButtonGroup class. We must add the radio button themselves to a panel ( so they are displayed ) and to a button group. Here is the usual way of creating a radio button.
JRadioButton pepsi, coke, tea;
Then in the frame constructor, we call the JRadioButton constructor to create the radio button:
pepsi = new JRadioButton("Pepsi");
Now we would add the radio button to the panel the usual way. Finally, to create a button group to group radio buttons that work together, we would just call the ButtonGroup class constructor.
ButtonGroup group = new ButtonGroup();
Then add the method of the ButtonGroup to add each radio button to the group
group.add(pepsi);
group.add(coke);
group.add(tea);
Lets observe an example
/*
The program demonstrate the use of JRadioButton
*
*/
import javax.swing.*;
public class RadioButton extends JFrame
{
JRadioButton pepsi, coke, tea;
JPanel panel = new JPanel();
public RadioButton()
{
// Sets the title
setTitle("Radio Button");
// Sets the window size
setSize(300, 400);
// Sets the action when the window close
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Create a button group to group the radio buttons together
ButtonGroup group = new ButtonGroup();
// Creates a radio button for pepsi
pepsi = new JRadioButton("Pepsi");
// Creates a radio button for coke
coke = new JRadioButton("Coke");
// Creates a radio button for Tea
tea = new JRadioButton("Tea");
// Add the radio button to the group
group.add(pepsi);
group.add(coke);
group.add(tea);
// Adds the button to the panel
panel.add(pepsi);
panel.add(coke);
panel.add(tea);
// Adds the panel to the content pane
add(panel);
// Sets the window to be visible
setVisible(true);
}
public static void main(String[] args)
{
new RadioButton();
}
}
Check Box
A check box is a control that the user can click to either check or uncheck. Check box is similar to radio buttons, and it's usually used to let the user specify Yes or No to an option. To create a check box, we use the JCheckBox class, then adds it to the panel.
JCheckBox ice_cream, banana, ribs;
The above statement declares the class variable to reference to the check box component. Then we can use the constructor from JCheckBox to create the check boxes and add them to the panel.
ice_cream = new JCheckBox("Ice Cream");
JPanel panel = new JPanel();
panel.add(ice_cream);
Notice that the above statements, we didn't specify which box is initially checked, so as a result they're initially unchecked. If we want to create a check box that is initially checked, we would create a constructor like the following:
ice_Cream = new JCheckBox("Ice Cream", true);
Again, Lets observe an example
/*
The program demonstrate a check box
It has an initial box checked
*
*/
import javax.swing.*;
public class CheckBox extends JFrame
{
JCheckBox ice_cream, banana, ribs;
JPanel panel;
public CheckBox()
{
// Sets the title of the window
setTitle("Check Bow Window");
// Sets the size of the window
setSize(300, 400);
// Sets the action when the window closes
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Creates a panel
panel = new JPanel();
// Creates 3 check box with ice_cream initially checked
ice_cream = new JCheckBox("Ice Cream", true);
banana = new JCheckBox("Banana");
ribs = new JCheckBox("Ribs");
// Adds the check boxes to the panel
panel.add(ice_cream);
panel.add(banana);
panel.add(ribs);
// Adds the panel to the content pane
add(panel);
// Sets the window to be visible
setVisible(true);
}
public static void main(String[] args)
{
new CheckBox();
}
}
The example above are all basic example on how to create JCheckBox and JRadioButton, although it isn't much of a use. Hence, after we learn about different layouts we will see more on how to use JCheckBox and JRadioButtons to do more interesting things.
Borders
A border is a decorative element that visually groups components by drawing a line around them. We can apply a border to any object that inherits JComponent. To create a border we can call one of the static methods from the BorderFactory methods which listed in " Swing Methods & Constructor Table. "
To create a border and add to the panel
JPanel panel = new JPanel();
Border b = BorderFactory.createTitledBorder("Title");
panel.setBorder(b );
Hence, any components we add to the panel appear within this border.
Example
/*
The program demonstrates bevel border
*
*/
import javax.swing.*;
import javax.swing.border.*;
public class BevelBorder extends JFrame
{
JPanel panel;
public BevelBorder()
{
// Sets the title of the window
setTitle("Border Window");
// Sets the size of window
setSize(300, 400);
// Sets the action when the window is close
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Creates a panel
panel = new JPanel();
// Creates a border name title
Border b = BorderFactory.createTitledBorder("Title");
panel.setBorder(b);
// Adds the panel to the content pane
add(panel);
// Sets the window to be visible
setVisible(true);
}
public static void main(String[] args)
{
new BevelBorder();
}
}
Now lets combine JCheckBox, JRadioButton, and BevelBorder together to create a ordering program. It's pretty long so bear with me.
/*
This is a small Starbucks order program
It demonstrate the use of BevelBorder, JCheckBox, & JRadioButton
*
*/
import javax.swing.*;
import java.awt.event.*;
import javax.swing.border.*;
public class Starbucks extends JFrame
{
JButton ok;
JPanel radiopanel;
JPanel checkboxpanel;
JPanel mainpanel;
JRadioButton tall, grande, venti;
JCheckBox ice_green, coffee, orange_juice;
public Starbucks()
{
// Sets title of the window
setTitle("Welcome to Starbucks");
// Sets the size of the window
setSize(300, 400);
// Sets the action if the window is close
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Creates a button listener
ButtonListener bl = new ButtonListener();
// Create two panels one for JRadioButton and one for the main panel
radiopanel = new JPanel();
mainpanel = new JPanel();
// Creates a border for JRadioButton
Border b = BorderFactory.createTitledBorder("Size");
// Adds the border to the radio panel
radiopanel.setBorder(b);
// Group the radio buttons together
ButtonGroup radiogroup = new ButtonGroup();
// Add the radio buttons to the panel and group
tall = new JRadioButton("Tall");
radiopanel.add(tall);
radiogroup.add(tall);
grande = new JRadioButton("Grande");
radiopanel.add(grande);
radiogroup.add(grande);
venti = new JRadioButton("Venti");
radiopanel.add(venti);
radiogroup.add(venti);
// Adds the JRadioButton panel to the main panel
mainpanel.add(radiopanel);
// Creates the JCheckBox panel
checkboxpanel = new JPanel();
// Creates a border for the check box panel
Border b2 = BorderFactory.createTitledBorder("Drinks");
// Adds the border to the check box
checkboxpanel.setBorder(b2);
// Create JCheckbox and add the check boxes into the panel
ice_green = new JCheckBox("Ice Green Tea");
checkboxpanel.add(ice_green);
coffee = new JCheckBox("Coffee");
checkboxpanel.add(coffee);
orange_juice = new JCheckBox("Orange Juice");
checkboxpanel.add(orange_juice);
// Adds the check box panel to the main panel
mainpanel.add(checkboxpanel);
// Creates a ok button
ok = new JButton("OK");
/*
Creates a listener for ok button to listen for any events
We pass the bl into the parameter, bl is created from the very beginning
*
*/
ok.addActionListener(bl);
// Adds the ok button into the main panel
mainpanel.add(ok);
// Adds the main panel into the content pane
add(mainpanel);
// Sets the window to be visible
setVisible(true);
}
/*
Inside here, all the events of JCheckBox and JRadioButton will be handled
*
*/
public class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==ok)
{
String drinks = "";
// Determine what is been selected in JCheck Box
if(ice_green.isSelected())
{
drinks += "Ice Green Tea\n";
}
if(coffee.isSelected())
{
drinks += "Coffee\n";
}
if(orange_juice.isSelected())
{
drinks += "Orange Juice\n";
}
// Determine what is been selected in JRadio Button
String msg = "You ordered a ";
if(tall.isSelected())
{
msg += " tall " + drinks;
}
if(grande.isSelected())
{
msg += " grande " + drinks;
}
if(venti.isSelected())
{
msg += " venti " + drinks;
}
// Outputs the order in JOptionPane
JOptionPane.showMessageDialog(null, msg);
/*
Deselected all the check box
Selects tall in radio button
*
*/
ice_green.setSelected(false);
coffee.setSelected(false);
orange_juice.setSelected(false);
tall.setSelected(true);
}
}
}
public static void main(String[] args)
{
new Starbucks();
}
}
The above program we created a main panel to hold the JCheckBox and JRadioButton panel. The idea of the above program is to put two panels inside another panel.
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