Exploring Pre-defined FileFilter Utilities in Java


Could you enlighten me on whether Java provides any pre-defined FileFilter classes for common file filtering tasks?


For example, if you want to filter and list all `.log` files in a directory, you can implement the `FileFilter` interface like this:


FileFilter logFileFilter = new FileFilter() {

public boolean accept(File file) { return file.getName().endsWith(“.log”); } }; “`

Then, you can use this filter with the `listFiles(FileFilter filter)` method of the `File` class, which represents a directory:


File directory = new File(“/path/to/directory”);

File[] logFiles = directory.listFiles(logFileFilter);


This will return an array of `File` objects representing the files ending with `.log` in the specified directory.

Java also provides the `FilenameFilter` interface, which works similarly but only tests the file name, not the file itself. This can be useful when you need to filter files based on their names alone.

Moreover, from Java SE 11 onwards, there’s the `FileNameExtensionFilter` class, which is an implementation of `FileFilter` that filters files based on their file name extension. It’s commonly used with `JFileChooser` to restrict the set of files shown to the user.

In summary, Java provides both the `FileFilter` and `FilenameFilter` interfaces for custom file filtering tasks, and also offers the `FileNameExtensionFilter` class for a more straightforward approach to filtering by file extension. These tools are quite flexible and can be adapted to various file filtering needs in Java applications.

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