4.4 Deprecated Features

Although you can use the old AWT event model in Java 1.1, it has been officially "deprecated," and its use in new software is discouraged. When you compile code that uses the 1.0 event model, you'll be made aware of this by the "deprecation warning" that the javac compiler issues. This warning notifies you that your code relies on methods or classes in the Java API that have been superseded by newer, preferred alternatives. If you compile using the -deprecation flag, javac provides a detailed warning about each use of a deprecated feature. You can simply ignore these warnings, but when time permits, the better approach is to update your code so that it no longer relies on deprecated features of the Java API. While it is not strictly true to say that deprecated features are "unsupported," they will almost certainly receive far less support in practice than the features that replace them.

The reason that the compiler is able to issue deprecation warnings at all is the addition of a new @deprecated tag to the documentation-comment syntax of Java 1.1. As you may be aware, comments that begin with the /** character sequence are treated specially in Java, and are used by the javadoc tool to automatically generate online documentation for packages, classes, methods, and fields. Prior to Java 1.1, the compiler ignored the contents of documentation comments. In Java 1.1, however, it scans these comments for the @deprecated tag. If it is found, the compiler marks the class, interface, constructor, method, or field following the comment as deprecated, and issues a warning when the deprecated feature is used.

The old AWT event-handling model is not the only Java 1.0 feature that has been deprecated in Java 1.1; merely the one you are most likely to encounter first. A number of common AWT component methods have been renamed, to follow a more regular naming scheme that fits the JavaBeans naming conventions. These methods can be invoked by the old name or the new, but if you use the old name, you'll be rewarded with a deprecation warning. Fortunately, in simple cases like this, it is trivial to write a script or program to mechanically convert from the old name to the new. Other areas of the Java API have been deprecated as well. You'll notice that a few of the input and output stream classes in the java.io package have been deprecated and superseded by "Reader" and "Writer" stream classes, for example.