DAT602 Database Application Development Lecture 6 JAVA Swing

Library of JAVA. In JAVA’s library, different packages contain classes with different functions. java.langjava.iojava.util javax.swing… Developers must import corresponding package in the resource code before using it. Database Application Development - Lecture 6

JFC and Swing JFC is short for Java Foundation Classes, which encompass a group of features for building graphical user interfaces (GUIs) and adding rich graphics functionality and interactivity to Java applications. This lecture’s topic is javax.swing. Database Application Development - Lecture 6

What is in javax.swing package ? What can swing provide to us ? Database Application Development - Lecture 6 FeatureDescription Swing GUI ComponentsIncludes everything from buttons to split panes to tables. Pluggable Look-and-Feel SupportThe look and feel of Swing applications is pluggable, allowing a choice of look and feel. Accessibility APIEnables assistive technologies, such as screen readers. Java 2D APIEnables developers to easily incorporate high-quality 2D graphics, text, and images in applications and applets. InternationalizationLanguage support.

What is container in JAVA swing ? Container is a set of Java classes, a container could be JFrame, JApplet or JDialog. These containers can be used for containing other Java swing components or containers. Database Application Development - Lecture 6

To appear onscreen, every GUI component must be part of a containment hierarchy. A containment hierarchy is a tree of components that has a top-level container as its root. Database Application Development - Lecture 6

containment hierarchy for this example's GUI

Database Application Development - Lecture 6 Top-Level Containers and Containment Hierarchies Each program that uses Swing components has at least one top-level container. This top- level container is the root of a containment hierarchy — the hierarchy that contains all of the Swing components that appear inside the top-level container.

The Root Pane Each top-level container relies on a reclusive intermediate container called the root pane. Database Application Development - Lecture 6

How to add a component to pane ? Here's the simple code that add a label to a container. container.add(yellowLabel, BorderLayout.CENTER); yellowLabel is a Label component. BorderLayout.CENTER indicate which kind of layout this component applied, and its position. Database Application Development - Lecture 6

In next slides, you will see some useful swing components. Button, Label, List, Panel, Password Field, Scroll Pane, Text Field. Database Application Development - Lecture 6

First, let’s see the JButton. In this part, we’ll use ButtonDemo for illustration.

Button. If you want using swing’s button component, you have to import following package in the beginning of your code. package: javax.swing.JButton import javax.swing.JButton; Database Application Development - Lecture 6

How to create a JButton ? JButton b1 = new JButton("Disable middle button", leftButtonIcon); A Swing button can display both text and an image. Database Application Development - Lecture 6

After a JButton being created, some properties should be set. b1 = new JButton("Disable middle button", leftButtonIcon); b1.setVerticalTextPosition(AbstractButton.CENTER); b1.setHorizontalTextPosition(AbstractButton.LEADING); //aka LEFT, for left-to- right locales b1.setMnemonic(KeyEvent.VK_D); b1.setActionCommand("disable"); Database Application Development - Lecture 6

After b1 being created, we also need to add a action listener to this new button. b1.addActionListener(this); What is action listener ? Action listener is a action capturer, it is used for notifying every time the user clicks the button. Database Application Development - Lecture 6

After all properties of button being set, and the action listener being bound with this button, then we can add this button to its higher level container. for example, add button b1 to a pane: pand.add(b1); Database Application Development - Lecture 6

For response the command from buttons, we should create a function to process different commands. public void actionPerformed(ActionEvent e) { if ("disable".equals(e.getActionCommand())) { b2.setEnabled(false); b1.setEnabled(false); b3.setEnabled(true); } Database Application Development - Lecture 6

JList A JList presents the user with a group of items, displayed in one or more columns, to choose from. Lists can have many items, so they are often put in scroll panes. Database Application Development - Lecture 6

Create and initializing a List JList list = new JList(listModel); //create a instance of Jlist list.setSelectionMode(ListSelectionModel.SINGLE_SELECT ION); // set a selection model list.setSelectedIndex(0);// the default selected item list.addListSelectionListener(this); // add a listener list.setVisibleRowCount(5); // number of visible records Database Application Development - Lecture 6

Choose a list model If you initialize a list with an array or vector, the constructor implicitly creates a default list model. The default list model is immutable — you cannot add, remove, or replace items in the list. ArrayList data = new ArrayList(); list = new JList(data); //data has type Object[] Database Application Development - Lecture 6

Choose a list model To create a list whose items can be changed individually, set the list‘s model to an instance of a mutable list model class, such as an instance of DefaultListModel. You can set a list's model when you create the list or by calling the setModel method. list.setModel(ListModel model); Database Application Development - Lecture 6

List selection mode you can use the method setSelectionMode to set the selecting model. SINGLE_SELECTIONSINGLE_INTERVAL_SELECTIONMULTIPLE_INTERVAL_SELECTIO Database Application Development - Lecture 6

Adding Items to and Removing Items from a List Before introduce add and remove operation. Here we creates a mutable list model object, puts the initial items in it, and uses the list model to create a list. We create a list for our example first. DefaultListModel listModel = new DefaultListModel(); listModel.addElement("Debbie Scott"); listModel.addElement("Scott Hommel"); listModel.addElement("Alan Sommerer"); JList list = new JList(listModel); Database Application Development - Lecture 6

Add a element to list. example: listModel.insertElementAt(employeeName.getText(), index); employeeName is a text field which is used for input new employee’s name. index is used for indicating where this new element be inserted. NOTE: add new element to the object list contains. Database Application Development - Lecture 6

Remove an element from list listModel.remove(index); index is used for indicating which element should be removed. You can indicate index manually, or you can use JList’s method getSelectedIndex to get the selected element’s index. Database Application Development - Lecture 6

Scroll Panes A JScrollPane provides a scrollable view of a component. When screen real estate is limited, use a scroll pane to display a component that is large or one whose size can change dynamically. Database Application Development - Lecture 6

Hot to create and initialize scroll pane ? JList list = new JList(array); JScrollPane scrollPane = new JScrollPane(list); You should also add this scroll pane to a higher level container. example: rootPane.add(scrollPane, BorderLayout.CENTER); Database Application Development - Lecture 6

Reference ing/components/index.html Database Application Development - Lecture 6