File Filters

The FileFilter interface is very similar to FilenameFilter:

public abstract interface FileFilter

The accept( ) method of FileFilter takes a single File object as an argument, rather than two strings giving the directory and path:

public boolean accept(File pathname)

Example 17-8 is a filter that only passes HTML files. Its logic is essentially the same as the filter of Example 17-7.

Example 17-8. HTMLFileFilter

import java.io.*;
public class HTMLFileFilter implements FileFilter {
 public boolean accept(File pathname) {
 if (pathname.getName( ).endsWith(".html")) return true;
 if (pathname.getName( ).endsWith(".htm")) return true;
 return false;
 }
}

This class appears as an argument in one of the listFiles( ) methods of java.io.File:

public File[] listFiles(FileFilter filter)

Example 17-9 uses the HTMLFileFilter to list the HTML files in the current working directory.

Example 17-9. List HTML files

import java.io.*;
public class HTMLFiles {
 public static void main(String[] args) {
 File cwd = new File(System.getProperty("user.dir"));
 File[] htmlFiles = cwd.listFiles(new HTMLFileFilter( ));
 for (int i = 0; i < htmlFiles.length; i++) {
 System.out.println(htmlFiles[i]);
 }
 }
}