Posted 27 September 2009 - 06:43 PM
Using a Spinner
A spinner is a text field that has two little arrows next to it. A user can click one of these arrows to increase or decrease the value in the text field. Usually, the value in the text field contains a number.
Creating a Spinner
JSpinner jspin = new JSpinner();
Getting value from a spinner we use the getValue method
int value = jspin.getValue();
Creating a spinner with a specify min and max number
JSpinner hours = new JSpinner(new SpinnerNumberModel(1, 1, 12, 1));
Lets see a example on it.
/*
The example demonstrate a simple spinner
It allows the user to choose the time
In addition, user can choose the am/pm
*
*/
import javax.swing.*;
import java.awt.event.*;
public class Spinner extends JFrame
{
private JPanel panel;
private JButton ok;
private JSpinner spinner;
public Spinner()
{
// Sets the title of the window
setTitle("JSpinner Window");
// Sets the size of the window
setSize(300, 200);
// Sets the start location of the window
setLocationRelativeTo(null);
// Sets the action when a window is close
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Creates a spinner with initial, min, and max value
spinner = new JSpinner(new SpinnerNumberModel(1, 1, 12, 1));
// Creates a OK button
ok = new JButton("OK");
// Creates an action listener for the button
ok.addActionListener(new okButtonListener());
// Creates a panel
panel = new JPanel();
// Adds the components to the panel
panel.add(spinner);
panel.add(ok);
// Adds the panel to the content pane
add(panel);
// Sets the visibility of the window
setVisible(true);
}
private class okButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==ok)
{
Object value = spinner.getValue();
JOptionPane.showMessageDialog(null, "You have selected " + value);
}
}
}
public static void main(String[] args)
{
new Spinner();
}
}
Using a Tree
A tree is a more fancy swing component that displays hierarchical data in outline form. The type of tree that we most see/familiar with is the directory structure of the disk drive. Before we start to learn how to create a tree, lets learn a few terms that describe the elements in the tree.
* Node: Each element in the tree is called a node. The nodes in a tree must be created from a class that implements the TreeNode interface.
* Root node: Root node is the starting node of a tree. Every tree components must only have one root node. When we create a tree component, we pass the
root node to the JTree Constructor.
* Parent node: The node that is immediately above a given node. Every node except the root node must have only one parent node.
* Child node: The node that appear immediately below a given node. A node can have more than one child nodes.
* Leaf node: A node that doesn't have any children. It represent the end of a branch.
* Sibling nodes: Nodes that are children of the same parent.
* Path: A node and all of its ancestors such as, its parent, its parent's parent and so on all the way up to the root node.
* Collapsed node: A node whose children are hidden.
* Expanded node: A node whose children are visible.
Building a Tree
The easiest way to build a tree is to use the DefaultMutableTreeNode class, It can be found inside the link below "Swing Method & Constructor Table." Since the DefaultMutableTreeNode class implements the TreeNode interface, we can use the DefaultMutableTreenode objects for any of the methods listed in the table called for TreeNode objects.
/*
This is a JTree program
*
*/
import javax.swing.*;
import java.awt.event.*;
import javax.swing.tree.*;
import javax.swing.event.*;
public class JTreeWindow extends JFrame
{
private JTree tree;
private DefaultTreeModel model;
private JLabel name;
private JPanel panel;
public JTreeWindow()
{
// Sets the title of the window
setTitle("JTree Window");
// Sets the size of the window
setSize(300, 400);
// Sets the start location of the window
setLocationRelativeTo(null);
// Sets the action when the window close
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Creates a panel
panel = new JPanel();
// Create a empty tree node
DefaultMutableTreeNode root, Program_Files, Windows, System_32;
// Creates the root directory
root = new DefaultMutableTreeNode("C");
// Adds program files, windows, and system 32 to the root directory
Program_Files = create("Program Files", root);
Windows = create("Program Files", root);
System_32 = create("System 32", root);
// Add files to the program file folder
create("Winamp", Program_Files);
create("JGrasp", Program_Files);
create("Dev++", Program_Files);
// Add files to the windows folder
create("Window Media", Windows);
create(".dll", Windows);
create(".temp", Windows);
// Add files to System 32
create(".source", System_32);
create("cookies", System_32);
create("bugs", System_32);
// Creates a tree that displays the tree that starts at the root node
tree = new JTree(root);
// Gets the model of the tree
tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
// Sets the number of rows visible in the display
tree.setVisibleRowCount(11);
// Create an even listener for the tree
tree.addTreeSelectionListener(new TreeListener());
// Add a scroll pane to the tree
JScrollPane sp = new JScrollPane(tree);
// Create a label
name = new JLabel();
// Add the scroll pane and label into the panel
panel.add(name);
panel.add(sp);
// Add the panel to the content pane
add(panel);
// Sets the visibility of the window
setVisible(true);
}
private DefaultMutableTreeNode create(String title, DefaultMutableTreeNode parent)
{
// Creates a tree node with a specified user object
DefaultMutableTreeNode creating = new DefaultMutableTreeNode(title);
// Adds it to the tree
parent.add(creating);
return creating;
}
private class TreeListener implements TreeSelectionListener
{
public void valueChanged(TreeSelectionEvent e)
{
// Gets the currently selected node
Object getSelect = tree.getLastSelectedPathComponent();
DefaultMutableTreeNode creating = (DefaultMutableTreeNode) getSelect;
String title = (String)creating.getUserObject();
name.setText(title);
}
}
public static void main(String[] args)
{
new JTreeWindow();
}
}
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