Setting an Icon Image

In this section, you will learn how to set an icon for the frame in Java Swing.

This program helps us to set the icon (image) on the title bar of the frame. When you open frame or window the icon situated on the title bar is seen on the taskbar also. For this purposes, various methods as follows has been used:

frame.setIconImage(Toolkit.getDefaultToolkit().getImage("siddu.jpg"));
Above method sets the icon for the frame or window after getting the image using the Image class method named getImage().

frame.getDefaultToolkit():
This is the method of the Toolkit class which gets the default toolkit.

Here is the code of program:

Output:

-Source:roseindia.net

Creating a JFrame

This program shows you how to create a frame in Java Swing Application. The frame in java works like the main window where your components (controls) are added to develop an application. In the Java Swing, top-level windows are represented by the JFrame class. Java supports the look and feel and decoration for the frame. 

For creating java standalone application you must provide GUI for a user. The most common way of creating a frame is, using single argument constructor of the JFrame class. The argument of the constructor is the title of the window or frame. Other user interface are added by constructing and adding it to the container one by one. The frame initially are not visible and to make it visible the setVisible(true) function is called passing the boolean value true. The close button of the frame by default performs the hide operation for the JFrame. In this example we have changed this behavior to window close operation by setting the setDefaultCloseOperation() to EXIT_ON_CLOSE value.

setSize (400, 400):
Above method sets the size of the frame or window to width (400) and height (400) pixels.

setVisible(true):
Above method makes the window visible.

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE):
Above code sets the operation of close operation to Exit the application using the System exit method.

Here is the code of the program : 

output:

JComponent

 JComponent Class

With the exception of top-level containers, all Swing components whose names begin with "J" descend from the JComponent class. For example, JPanel, JScrollPane, JButton, and JTable all inherit from JComponent. However, JFrame and JDialog don't because they implement top-level containers. The JComponent class extends the Container class, which itself extends Component. The Component class includes everything from providing layout hints to supporting painting and events. The Container class has support for adding components to the container and laying them out. This section's API tables summarize the most often used methods of Component and Container, as well as of JComponent.

JComponent Features

The JComponent class provides the following functionality to its descendants:

Tool tips

By specifying a string with the setToolTipText method, you can provide help to users of a component. When the cursor pauses over the component, the specified string is displayed in a small window that appears near the component. See How to Use Tool Tips for more information.

Painting and borders

The setBorder method allows you to specify the border that a component displays around its edges. To paint the inside of a component, override the paintComponent method. See How to Use Borders and Performing Custom Painting for details.

Application-wide pluggable look and feel

Behind the scenes, each JComponent object has a corresponding ComponentUI object that performs all the drawing, event handling, size determination, and so on for that JComponent. Exactly which ComponentUI object is used depends on the current look and feel, which you can set using the UIManager.setLookAndFeel method. See How to Set the Look and Feel for details.

Custom properties

You can associate one or more properties (name/object pairs) with any JComponent. For example, a layout manager might use properties to associate a constraints object with each JComponent it manages. You put and get properties using the putClientProperty and getClientProperty methods. For general information about properties, see Properties.

Support for layout

Although the Component class provides layout hint methods such as getPreferredSize and getAlignmentX, it doesn't provide any way to set these layout hints, short of creating a subclass and overriding the methods. To give you another way to set layout hints, the JComponent class adds setter methods — setMinimumSize, setMaximumSize, setAlignmentX, and setAlignmentY. See Laying Out Components Within a Container for more information.

Support for accessibility

The JComponent class provides API and basic functionality to help assistive technologies such as screen readers get information from Swing components, For more information about accessibility, see How to Support Assistive Technologies.

Support for drag and drop

The JComponent class provides API to set a component's transfer handler, which is the basis for Swing's drag and drop support. See Introduction to DnD for details.

Double buffering

Double buffering smooths on-screen painting. For details, see Performing Custom Painting.

Key bindings

This feature makes components react when the user presses a key on the keyboard. For example, in many look and feels when a button has the focus, typing the Space key is equivalent to a mouse click on the button. The look and feel automatically sets up the bindings between pressing and releasing the Space key and the resulting effects on the button. For more information about key bindings, see How to Use Key Bindings. 

-Source:Oracle.com

Swings

    This lesson gives you the background information you need to use the Swing components, and then     describes every Swing component. It assumes that you have successfully compiled and run a program that uses Swing components, and that you are familiar with basic Swing concepts.

Before you get started, you may want to check out these pages (from the Graphical User Interfaces lesson in the Core trail) which have pictures of all the standard Swing components, from top-level containers to scroll panes to buttons. To find the section that discusses a particular component, just click the component's picture.

Using Top-Level Containers

Discusses how to use the features shared by the JFrame, JDialog, and JApplet classes — content panes, menu bars, and root panes. It also discusses the containment hierarchy, which refers to the tree of components contained by a top-level container.

The JComponent Class

Tells you about the features JComponent provides to its subclasses — which include almost all Swing components — and gives tips on how to take advantage of these features. This section ends with API tables describing the commonly used API defined by JComponent and its superclasses, Container and Component.

Using Text Components

Describes the features and API shared by all components that descend from JTextComponent. You probably do not need to read this section if you are just using text fields (formatted or not) or text areas.

How to...

Sections on how to use each Swing component, in alphabetical order. We do not expect you to read these sections in order. Instead, we recommend reading the relevant "How to" sections once you are ready to start using Swing components in your own programs. For example, if your program needs a frame, a label, a button, and a color chooser, you should read How to Make Frames, How to Use Labels, How to Use Buttons, and How to Use Color Choosers.

Using HTML in Swing Components

Describes how to vary the font, color, or other formatting of text displayed by Swing components by using HTML tags.

Using Models

Tells you about the Swing model architecture. This variation on Model-View-Controller (MVC) means that you can, if you wish, specify how the data and state of a Swing component are stored and retrieved. The benefits are the ability to share data and state between components, and to greatly improve the performance of components such as tables that display large amounts of data.

Using Borders

Borders are very handy for drawing lines, titles, and empty space around the edges of components. (You might have noticed that the examples in this trail use a lot of borders.) This section tells you how to add a border to any JComponent.

Using Icons

Many Swing components can display icons. Usually, icons are implemented as instances of the ImageIcon class.