JAVA GUI PART I

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JAVA GUI

PART I Milad Kawesh

» GUI ˃ Introduction

˃ AWT Package

˃ Swing Package

˃ Frame vs. JFrame


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Agenda

» Introduction

˃ GUI (Graphical User Interface)

˃ Simple Example

» AWT and Swing Package

˃ AWT

˃ Swing

˃ JFrame vs. Frame

˃ Simple Example

2


Introduction

» A Graphical User Interface (GUI) presents a

user-friendly mechanism for interacting with

an application.

˃ Gives an application a distinctive "look" and "feel".

˃ Consistent, intuitive user-interface components give users a sense of

familiarity .

˃ Learn new applications more quickly and use them more

productively. 3


Introduction (cont..)

» Built from GUI components.

˃ Sometimes called controls or widgets

» User interacts via the mouse, the keyboard or another

form of input, such as voice recognition.

» IDEs

˃ Provide GUI design tools to specify a component's exact size and location in a visual

manner by using the mouse.

˃ Generates the GUI code for you.

˃ Greatly simplifies creating GUIs, but each IDE has different capabilities and generates

different code.

4


Simple GUI-Based Input / Output with JOptionPane

» Most applications use windows or dialog boxes (also called

dialogs) to interact with the user.

» JOptionPane (javax.swing package) provides prebuilt dialog

boxes for input and output

˃ Displayed via static JOptionPane methods.

» Next Example uses two input dialogs to get input from the

user and a message dialog to display the sum of the given

input. 5


Simple GUI example import javax.swing.JOptionPane;

public class Multiplier {

public static void main(String[] args) {

String firstNumber = JOptionPane.showInputDialog("Enter first number");

String secondNumber = JOptionPane.showInputDialog("Enter Second number");

int number1 = Integer.parseInt(firstNumber);

int number2 = Integer.parseInt(secondNumber);

int result = number1 * number2;

JOptionPane.showMessageDialog(null, "The Multiply of " + number1

+ " and " +number2 + " is " + result, "Result", JOptionPane.PLAIN_MESSAGE);

}

} 6


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Preview

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More on GUI "AWT and Swing"

8

AWT Vs. Swing

» When Java was first released in 1995, it contained a GUI API

referred to as the Abstract Windowing Toolkit (AWT).

» The classes and interfaces of the AWT are in the java.awt

package.

» Aware of the need for a more robust API for creating GUI

applications, Sun Microsystems teamed together with

Netscape (and other industry partners) then created Swing

package.

9


AWT Vs. Swing (cont.)

» Swing is actually a part of the Java Foundation Classes

(JFC).

» The classes and interfaces of Swing are found in the

javax.swing package.

» AWT components are referred to as heavyweight

components because their implementation relies

heavily on the underlying Operating System. 10


AWT Vs. Swing (cont.) » The look and feel of AWT components depend on the platform

the program is running on.

˃ For example, an AWT button will look like a Windows button when the program is run on a Windows

platform.

» Swing components are referred to as lightweight components

because their implementation does not rely on the underlying

Operating System.

» Because Swing components are lightweight, their appearance is

determined by you, the programmer, and not by which platform

the program is running. 11


Converting Frame to JFrame

» The names of the Swing classes all begin with a capital

"J" , like JButton, JLabel, JFrame.

» For the most part, an AWT program can be converted

to a Swing program by adding a capital J to the class

names used in the source code and recompiling the

code.

12


Creating Windows » The basic starting point of a GUI is the container because you need a

container before you can start laying out your components.

» The java.awt.Frame and javax.swing.JFrame classes are containers that

represent a basic window with a title bar and common windowing capabilities

such as resizing, minimizing, maximizing, and closing.

» When working with JFrame objects, there are basically three steps involved to

get a JFrame window to appear on the screen:

˃ Instantiate the JFrame object in memory.

˃ Give the JFrame object a size using setSize(), setBounds(), or pack().

˃ Make the Frame appear on the screen by invoking setVisible(true). 13


JFrame and Frame Constructors The java.awt.Frame class has four constructors:

» public Frame() or JFrame()

˃ Creates a new frame with no message in the title bar.

» public Frame(String title) or JFrame(String title)

˃ Creates a new frame with the given String appearing in the title bar.

» public Frame(GraphicsConfiguration gc) or

JFrame(GraphicsConfiguration gc)

˃ Creates a frame with the specified GraphicsConfiguration of a screen device.

» public Frame(String title, GraphicsConfiguration gc) or JFrame(String

title, GraphicsConfiguration gc)

˃ Creates a frame with the specified title and GraphicsConfiguration. 14


javax.swing.JFrame Class » The javax.swing.JFrame class represents a window similar to

Frame, except that JFrame adds support for the Swing

component architecture.

» However, a JFrame is different in terms of how components are

added to the Frame.

» A JFrame has three panes that components can be added to:

˃ a content pane

˃ a glass pane

˃ and a root pane.

» Typically, the content pane will contain all of the components of

the JFrame. 15


Simple Example of JFrame import javax.swing.JFrame;

public class GUIDemo {

public static void main(String[] args) {

JFrame window = new JFrame(); //create frame in memory

window.setTitle( "Oxus20" ); // Set tittle to frame

window.setSize(300, 300); // Set Size to frame

window.setLocationRelativeTo(null); //Set location to center of monitor

//let program to close

window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

window.setVisible(true); // Let frame to be visible on screen

}

} 16


END


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