FilenameFilter

FilenameFilter is an interface used to filter filenames. FilenameFilter has a special method called accept that returns a boolean value (true or false). The accept(File dir, String name) method allows you to filter filenames. For example, you may want to show only Java files (*.java) in a directory. To accomplish this task, in the accept method you need to test whether the name argument ends with .java. To use the FilenameFilter interface, You will need a class that implements it. Then create an instance of the class and supply this object to the list method of the File instance.

Example: show only java files from d:/myprogram directory

import java.io.File;
import java.io.FilenameFilter;

public class FilesList{

public static void main(String[] args){

showFileNames("d:/myprogram","java");

}

public static void showFileNames(String src, String ext){

File f=new File(src); //create file object to connect to the source directory
if(!f.exists()){
System.out.println("Source directory does not exist.");
System.exit(-1);
}

String[] filenames;
if(!ext.equals("")){
filenames=f.list(new ExtFilter(ext)); //list files by extension
for(String name:filenames){
System.out.println(name);
}
}


}



}

class ExtFilter implements FilenameFilter{
String ext="";
public ExtFilter(String ext){
this.ext="."+ext;
}
public boolean accept(File f, String name){
if(name.endsWith(ext)) return true;
else return false;

}
}