Standard Widget Toolkit
Overview
The Standard Widget Toolkit (SWT) is a graphical widget toolkit for use with the Java platform. It was originally developed by IBM and is now maintained by the Eclipse Foundation in parallel with the Swing library. Both are used to build graphical user interfaces (GUIs) for Java programs, but they differ in their design philosophies and usage patterns.
Design Philosophy
SWT's design is heavily influenced by the principles of native OS widget systems. It uses native widgets wherever possible, falling back to emulated widgets only when the native equivalent is not available. This approach is in contrast to Swing, which emulates all widgets to ensure consistent behavior across platforms. The use of native widgets gives SWT applications a look and feel that is more consistent with other applications on the same platform and can also result in improved performance.
Architecture
SWT is a low-level toolkit. It does not include higher-level components like trees, tables, or text editors. Instead, these are built using the basic widgets provided by SWT. This approach allows for a high degree of customization and control, but it also means that more work is required to build complex interfaces.
SWT uses a system of handles to refer to native widgets. Each handle is a unique identifier that can be used to manipulate the corresponding widget. Handles are created and destroyed as needed, and they are managed by the SWT library.
Event Handling
SWT uses a listener-based model for event handling. Applications can register listeners for various types of events, such as button clicks or mouse movements. When an event occurs, SWT will call the appropriate listener method. This model is similar to the event handling model used by Swing and other Java GUI libraries.
Integration with Other Technologies
SWT can be used in conjunction with other technologies to build more complex applications. For example, it can be used with the JavaFX library to create rich internet applications, or with the Eclipse platform to build integrated development environments (IDEs).
Advantages and Disadvantages
One of the main advantages of SWT is its native look and feel. Because it uses native widgets, applications built with SWT will look and behave like other applications on the same platform. This can make them more intuitive for users and can also result in improved performance.
However, the use of native widgets also has some disadvantages. It can lead to inconsistencies between different platforms, and it can make it more difficult to create custom widgets. Additionally, because SWT is a low-level toolkit, it requires more work to build complex interfaces than higher-level toolkits like Swing.