How to Use File.listFiles with FileNameExtensionFilter in Java

How can I use File.listFiles with FileNameExtensionFilter without encountering a compilation error?

FileNameExtensionFilter filter = new FileNameExtensionFilter("text only","txt");
String dir  = "/users/blah/dirname";
File f[] = (new File(dir)).listFiles(filter);

Using the `File.listFiles(FileFilter filter)` method in Java allows you to filter files based on certain criteria. However, when using `FileNameExtensionFilter`, an important detail about the class hierarchy must be understood to avoid compilation errors.

File[] files = (new File(dir)).listFiles(new FileFilter() {
    public boolean accept(File file) {
        return file.isFile() && file.getName().endsWith(".txt");
    }
});

Causes

• You are trying to use `FileNameExtensionFilter` directly with the `listFiles()` method, but this class does not match the expected parameter type.

Solutions

• Use the correct filter type. Instead of using `FileNameExtensionFilter`, use a custom filter subclassed from `FileFilter`.
• Alternatively, use lambda expressions along with the `Files` class to accomplish similar results.

Mistake: Using FileNameExtensionFilter directly with listFiles, which expects a FileFilter.

Solution: Define a custom FileFilter that implements the accept method to check file extensions.

Mistake: Assuming that all filters that extend from FileFilter can be passed interchangeably without checking method signatures.

Solution: Always verify that the method parameter styles match precisely with methods being called.