AWT Components in Java

Java AWT, which is abbreviated as Abstract Window Toolkit, is nothing but a set of API’s used in order to develop Graphical User Interface or applications based on windows. AWT components in java are platform-dependent components that mean a display of components on a graphical user interface depends on the underlying operating system; AWT components are generally heavy components that make high use of operating system resources.

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Syntax:

Given below is a syntax of how AWT components are used:

// importing awt package
import java.awt.*;
// create a class extending Frame component
class <classname> extends Frame{
<classname>(){
Button button=new Button("<text_to_display_on_button>");  // create instance of component
button.setBounds(40,90,80,30);// call method to set button position
add(button);//    adding component to the container
setSize(400,400);//set size of container
setVisible(true);//set visibility of container to true
}
public static void main(String args[]){
<classname> clsobj=new <classname>();
}}</classname></classname></text_to_display_on_button></classname></classname>

The above syntax shows how to use a Button component of the AWT package.

In the above syntax denotes name of java class. can be set according to our functionality.

Different AWT Components

An AWT component can be considered as an object that can be made visible on a graphical interface screen and through which interaction can be performed.

In java.awt package, the following components are available:

1. Containers: As the name suggests, this awt component is used to hold other components.

Basically, there are the following different types of containers available in java.awt package:

a. Window: This is a top-level container and an instance of a window class that does not contain a border or title.

b. Frame: Frame is a Window class child and comprises the title bar, border and menu bars. Therefore, the frame provides a resizable canvas and is the most widely used container used for developing AWT-based applications. Various components such as buttons, text fields, scrollbars etc., can be accommodated inside the frame container.

Java Frame can be created in two ways:

• By Creating an object of Frame class.
• By making Frame class parent of our class.
  • Dialog: Dialog is also a child class of window class, and it provides support for the border as well as the title bar. In order to use dialog as a container, it always needs an instance of frame class associated with it.
  • Panel: It is used for holding graphical user interface components and does not provide support for the title bar, border or menu.

2. Button: This is used to create a button on the user interface with a specified label. We can design code to execute some logic on the click event of a button using listeners.

3. Text Fields: This component of java AWT creates a text box of a single line to enter text data.

4. Label: This component of java AWT creates a multi-line descriptive string that is shown on the graphical user interface.

5. Canvas: This generally signifies an area that allows you to draw shapes on a graphical user interface.

6. Choice: This AWT component represents a pop-up menu having multiple choices. The option which the user selects is displayed on top of the menu.

7. Scroll Bar: This is used for providing horizontal or vertical scrolling feature on the GUI.

8. List: This component can hold a list of text items. This component allows a user to choose one or more options from all available options in the list.

9. Checkbox: This component is used to create a checkbox of GUI whose state can be either checked or unchecked.

Example of AWT Components in Java

The following example shows the use of different AWT components available in java.

Code:

package com.edubca.awtdemo;
package com.edubca.awtdemo;
import java.applet.Applet;
// import awt and its subclasses
import java.awt.*;
// class extending applet
public class AWTDemo extends Applet {
// this method gets automatically called
public void init() {
Button button = new Button("Click Here to Submit");  // creating a button
this.add(button); // adding button to container
Checkbox checkbox = new Checkbox("My Checkbox"); // creating a checkbox
this.add(checkbox); //adding checkbox to container
CheckboxGroup checkboxgrp = new CheckboxGroup();  // creating checkbox group
this.add(new Checkbox("Check box Option 1", checkboxgrp, false));
this.add(new Checkbox("Check box Option 2", checkboxgrp, false));
this.add(new Checkbox("Check box Option 3", checkboxgrp, true));
// adding to container
Choice choice = new Choice();     // creating a choice
choice.addItem("Choice Option 1");
choice.addItem("Choice Option 2");
choice.addItem("Choice Option 3");
this.add(choice);     //adding choice to container
Label label = new Label("Demo Label");  // creating a label
this.add(label); //adding label to container
TextField textfield = new TextField("Demo TextField", 30);    // creating a Textfield
this.add(textfield);        // adding Textfield to container
}
}

The above program shows how to use AWT components like buttons, Checkboxes, Checkbox group, Labels, Choice and Text Fields in java code.

Output:

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