Read files in directory

Question

I'm trying to read in files with a specific name from a directory with this code:
String s=" ";
File dir = new File ("c:\test");
String myFiles [] = dir.list();     
for(int i=0;i<myFiles.length;i++)
f(myFiles.substring(0,3).equals("test"))
BufferedReader br = new BufferedReader( new FileReader("c:/test" + "/" + myFiles ) );
s = br.readLine();
however I get null pointer exception error when I try to run it.
What am I doing wrong?

Answer 1

"\t" means a tab character. Escape the path properly:
This isn't a good way to do it. Have a look at the java.io.FileFilter interface. It's a more flexible, object-oriented way to do.
Why not encapsulate this into a method and pass in the directory path?
This works very nicely:
import java.io.*;
import java.util.*;
public class DirectoryContentsReader
    public static final int DEFAULT_BUFFER_SIZE = 2048;
    public static void main(String [] args)
        try
            if (args.length > 1)
                Map contents = DirectoryContentsReader.read(new File(args[0]), new FilenameSubstringFilter(args[1]));
                System.out.println(contents);
            else
                System.out.println("Usage: java DirectoryContentsReader <directory path> <filename substring>");
        catch (Exception e)
            e.printStackTrace();
    public static Map read(File directory, FileFilter nameFilter) throws IOException
        Map directoryContents = new TreeMap();
        File [] files = directory.listFiles(nameFilter);
        StringBuffer fileContents = null;
        for (int i = 0; i < files.length; ++i)
            if (files.isFile() && files[i].canRead())
fileContents = new StringBuffer(DEFAULT_BUFFER_SIZE);
BufferedReader br = new BufferedReader(new FileReader(files[i]));
String line = "";
String newline = System.getProperty("line.separator");
while ((line = br.readLine()) != null)
fileContents.append(line);
fileContents.append(newline);
br.close();
directoryContents.put(files[i].getCanonicalPath(), fileContents.toString());
return directoryContents;
class FilenameSubstringFilter implements FileFilter
private String substring = "";
public FilenameSubstringFilter(String substring)
this.substring = substring;
public boolean accept(File candidate)
return (candidate.getName().indexOf(substring) != -1);