Understanding AWT and the java.awt package, learning about Swing components and the javax.swing package, manually coding GUI programs, mastering common basic Swing component usage methods, and familiarizing with commonly used layout managers such as FlowLayout, BorderLayout, GridLayout. Using JPanel to implement complex layouts.
Concept of GUI: So far, we have only written console-based programs in C and Java; GUI (Graphical User Interface) makes applications appear more user-friendly. One major reason for the popularity of Java is its support for GUIs.
Introduction to AWT: In the previous chapter, we learned that GUI programming is accomplished through a series of graphical components (i.e., predefined classes), known as controls. In early versions of Java, these GUI components were provided by a standard library called AWT (Abstract Window Toolkit). Besides GUI components, AWT also includes functionalities for image painting, handling cut/copy data transfer types, and other related operations.
the java.awt package is built into Java and is part of the core class library (JFC), which includes:
- A rich set of interface components for user input;
- Several layout managers to position components appropriately;
- An event handling model;
- Graphics and image tools; etc. To use classes from this package explicitly declare: import java.awt.*;
The biggest drawback of AWT components is their dependency on the operating system; meaning that an AWT program will look different when run on different systems—this contradicts Java's platform independence.
Introduction to Swing and javax.swing Package: Swing components are lightweight elements developed based on AWT ones. Compared to AWT they not only improve user interfaces but also require fewer system resources; being pure Java means applications maintain consistent appearance across platforms. The javax.swing package contains a range of Swing components requiring explicit declaration like so: import javax.swing.*;
In Swing programming there are frequently used components including JFrame (window/frame), JButton (button), JLabel (label), JTextField (text box). jFrame component creates windows within swing programs; it has four overloaded constructors with some common forms: description 1 - JFrame() creates a new window initially invisible, description 2 - JFrame(String title) creates a new window using parameter title specifying its title while remaining invisible.