Java Swing Continue Part 4

Swing

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(); } }

ClickHere to download Spinner.java

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(); } }

ClickHere to download JTreeWindow.java

The above program, a method DefaultMutableTree is created, hence we use the method to create the root folder, files and other folders.