The Abstract Window Toolkit (AWT) is Java's original platform-independent windowing, graphics, and user-interface widget toolkit. The AWT is part of the Java Foundation Classes (JFC) — the standard API for providing a graphical user interface (GUI) for a Java program. AWT is also the GUI toolkit for a number of Java ME profiles. For example, Connected Device Configuration profiles require Java runtimes on mobile telephones to support AWT.
Abstract Window Toolkit (AWT) is a set of application program interfaces ( API s) used by Java programmers to create graphical user interface ( GUI ) objects, such as buttons, scroll bars, and windows. AWT is part of the Java Foundation Classes ( JFC ) from Sun Microsystems, the company that originated Java. The JFC are a comprehensive set of GUI class libraries that make it easier to develop the user interface part of an application program.
A more recent set of GUI interfaces called Swing extends the AWT so that the programmer can create generalized GUI objects that are independent of a specific operating system's windowing system .
user interface
The user interface is that part of a program that interacts with the user of the program. User interfaces take many forms. These forms range in complexity from simple command-line interfaces to the point-and-click graphical user interfaces provided by many modern applications.
At the lowest level, the operating system transmits information from the mouse and keyboard to the program as input, and provides pixels for program output. The AWT was designed so that programmers don't have worry about the details of tracking the mouse or reading the keyboard, nor attend to the details of writing to the screen. The AWT provides a well-designed object-oriented interface to these low-level services and resources.
Because the Java programming language is platform-independent, the AWT must also be platform-independent. The AWT was designed to provide a common set of tools for graphical user interface design that work on a variety of platforms. The user interface elements provided by the AWT are implemented using each platform's native GUI toolkit, thereby preserving the look and feel of each platform. This is one of the AWT's strongest points. The disadvantage of such an approach is the fact that a graphical user interface designed on one platform may look different when displayed on another platform.
Components and containers
A graphical user interface is built of graphical elements called components. Typical components include such items as buttons, scrollbars, and text fields. Components allow the user to interact with the program and provide the user with visual feedback about the state of the program. In the AWT, all user interface components are instances of class Component or one of its subtypes.
Components do not stand alone, but rather are found within containers. Containers contain and control the layout of components. Containers are themselves components, and can thus be placed inside other containers. In the AWT, all containers are instances of class Container or one of its subtypes.
Spatially, components must fit completely within the container that contains them. This nesting of components (including containers) into containers creates a tree of elements, starting with the container at the root of the tree and expanding out to the leaves, which are components such as buttons.
.Types of components
The applet on this page shows you the graphical UI components we provide. Every graphical UI component is implemented with a subclass of the AWT Component class.
The AWT provides nine basic non-container component classes from which a user interface may be constructed. (Of course, new component classes may be derived from any of these or from class Component itself.) These nine classes are class Button, Canvas, Checkbox, Choice, Label, List, Scrollbar, TextArea, and TextField.
Following components of Java AWT are explained :
1. Labels : This is the simplest component of Java Abstract Window Toolkit. This component is generally used to show the text or string in your application and label never perform any type of action. Syntax for defining the label only and with justification :
Example: -
import java.awt.*;
import java.awt.event.*;
public class AwtControlDemo {
private Frame mainFrame;
private Label headerLabel;
private Label statusLabel;
private Panel controlPanel;
public AwtControlDemo(){
prepareGUI();
}
public static void main(String[] args){
AwtControlDemo awtControlDemo = new AwtControlDemo();
awtControlDemo.showLabelDemo();
}
private void prepareGUI(){
mainFrame = new Frame("Java AWT Examples");
mainFrame.setSize(400,400);
mainFrame.setLayout(new GridLayout(3, 1));
mainFrame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent windowEvent){
System.exit(0);
}
});
headerLabel = new Label();
headerLabel.setAlignment(Label.CENTER);
statusLabel = new Label();
statusLabel.setAlignment(Label.CENTER);
statusLabel.setSize(350,100);
controlPanel = new Panel();
controlPanel.setLayout(new FlowLayout());
mainFrame.add(headerLabel);
mainFrame.add(controlPanel);
mainFrame.add(statusLabel);
mainFrame.setVisible(true);
}
private void showLabelDemo(){
headerLabel.setText("Control in action: Label");
Label label = new Label();
label.setText("Welcome to Elearning AWT Tutorial.");
label.setAlignment(Label.CENTER);
//Justification of label can be left, right or centered. label.setBackground(Color.GRAY);
label.setForeground(Color.WHITE);
controlPanel.add(label);
mainFrame.setVisible(true);
}
}
Output: -
C:\java\awt>javac AwtControlDemo.java
C:\java\awt>java AwtControlDemo
2. Buttons : This is the component of Java Abstract Window Toolkit and is used to trigger actions and other events required for your application.
Example: -
import java.awt.*;
class First2{
First2(){
Frame f=new Frame();
Button b=new Button("Anuj");
b.setBounds(30,50,80,30);
f.add(b);
f.setSize(300,300);
f.setLayout(null);
f.setVisible(true);
}
public static void main(String args[]){
First2 f=new First2();
}
}
Output: -
C:\java\awt>javac First2.java
C:\java\awt>java First2
3. Check Boxes : This component of Java AWT allows you to create check boxes in your applications.
import java.awt.*;
import java.awt.event.*;
public class AwtControlDemo {
private Frame mainFrame;
private Label headerLabel;
private Label statusLabel;
private Panel controlPanel;
public AwtControlDemo(){
prepareGUI();
}
public static void main(String[] args){
AwtControlDemo awtControlDemo = new AwtControlDemo();
awtControlDemo.showCheckBoxDemo();
}
private void prepareGUI(){
mainFrame = new Frame("Java AWT Examples");
mainFrame.setSize(400,400);
mainFrame.setLayout(new GridLayout(3, 1));
mainFrame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent windowEvent){
System.exit(0);
}
});
headerLabel = new Label();
headerLabel.setAlignment(Label.CENTER);
statusLabel = new Label();
statusLabel.setAlignment(Label.CENTER);
statusLabel.setSize(350,100);
controlPanel = new Panel();
controlPanel.setLayout(new FlowLayout());
mainFrame.add(headerLabel);
mainFrame.add(controlPanel);
mainFrame.add(statusLabel);
mainFrame.setVisible(true);
}
private void showCheckBoxDemo(){
headerLabel.setText("Control in action: CheckBox");
Checkbox chkApple = new Checkbox("Apple");
Checkbox chkMango = new Checkbox("Mango");
Checkbox chkPeer = new Checkbox("Peer");
chkApple.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
statusLabel.setText("Apple Checkbox: "
+ (e.getStateChange()==1?"checked":"unchecked"));
}
});
chkMango.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
statusLabel.setText("Mango Checkbox: "
+ (e.getStateChange()==1?"checked":"unchecked"));
}
});
chkPeer.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
statusLabel.setText("Peer Checkbox: "
+ (e.getStateChange()==1?"checked":"unchecked"));
}
});
controlPanel.add(chkApple);
controlPanel.add(chkMango);
controlPanel.add(chkPeer);
mainFrame.setVisible(true);
}
}
Output: -
C:\java\awt>javac AwtControlDemo.java
C:\java\awt>java AwtControlDemo
