Basic Abstract Window Toolkit (AWT) Interview Preparation Guide

Download PDF

JFC stands for Java Foundation Classes. The Java Foundation Classes (JFC) are a set of Java class libraries provided as part of Java 2 Platform, Standard Edition (J2SE) to support building graphics user interface (GUI) and graphics functionality for client applications that will run on popular platforms such as Microsoft Windows, Linux, and Mac OSX.

Changing the state of an object is called an event.

setBounds

Event-delegation model has two advantages over event-inheritance model. a)Event delegation model enables event handling by objects other than the ones that generate the events. This allows a clean separation between a component's design and its use. b)It performs much better in applications where many events are generated. This performance improvement is due to event-delegation model does not have to be repeatedly process unhandled events as is the case of the event-inheritance.

Controls are components that allow a user to interact with your application. AWT supports the following types of controls: Labels, Push Buttons, Check Boxes, Choice Lists, Lists, Scrollbars, Text Components. These controls are subclasses of Component.

A Scrollbar is a Component, but not a Container whereas Scrollpane is a Container and handles its own events and perform its own scrolling.

The elements of a FlowLayout are organized in a top to bottom, left to right fashion. The elements of a BorderLayout are organized at the borders (North, South, East and West) and the center of a container. The elements of a CardLayout are stacked, on top of the other, like a deck of cards. The elements of a GridLayout are of equal size and are laid out using the square of a grid. The elements of a GridBagLayout are organized according to a grid. However, the elements are of different size and may occupy more than one row or column of the grid. In addition, the rows and columns may have different sizes. It is the most flexible layout.

Applets cannot read or write files on the client machine that's executing it. They cannot load libraries or access native libraries. They cannot make network connections except to the host that it came from. They cannot start any program on the client machine. They cannot read certain system properties. Windows that an applet brings up look different than windows that an application brings up.

An event-listener interface defines the methods that must be implemented by an event handler for a particular kind of event. An event adapter provides a default implementation of an event-listener interface.

The paint() method supports painting via a Graphics object. The repaint() method is used to cause paint() to be invoked by the AWT painting thread.

Canvas is a Component subclass which is used for drawing and painting. Canvas is a rectangular area where the application can draw or trap input events.

Pluggable Look-and-Feel, Accessibility API, Java 2D API, Drag and Drop Support.

They are light weight components that perform no painting, but can take space in the GUI. This is mainly used for layout management.

Realized mean that the component has been painted on screen or that is ready to be painted. Realization can take place by invoking any of these methods. setVisible(true), show() or pack().

JComponent is a subclass of Container and can contain other components and JComponents.

SWT (Standard Widget Toolkit) is a completely independent Graphical User Interface (GUI) toolkit from IBM. They created it for the creation of Eclipse Integrated Development Environment (IDE). AWT is from Sun Microsystems.

Converter is an application that converts distance measurements between metric and U.S units.

The enableEvents() method is used to enable an event for a particular object. Normally, an event is enabled when a listener is added to an object for a particular event. The enableEvents() method is used by objects that handle events by overriding their event-dispatch methods.

The java.awt.AWTEvent class is the highest-level class in the AWT event-class hierarchy.

The Frame class extends Window to define a main application window that can have a menu bar. A window can be modal.

Java uses layout managers to lay out components in a consistent manner across all windowing platforms. Since Java's layout managers aren't tied to absolute sizing and positioning, they are able to accommodate platform-specific differences among windowing systems.

This method is used to ensure that Swing components are updated through the event-dispatching thread.

When a window is repainted by the AWT painting thread, it sets the clipping regions to the area of the window that requires repainting.

A Canvas object provides access to a Graphics object via its paint() method.

The CheckboxMenuItem class extends the MenuItem class to support a menu item that may be checked or unchecked.