CODEWITHSUNDEEP
javarecursion
Lolly
Lolly

Reputation: 36372

Java to traverse all directories and find a file

I have to search for a file which can be in any directory or drive. It should be compatible with any operating system. When I googled, most of the code iterates through a particular directory but not full file system. Is there any way to do it efficiently ? Any help or suggestion will be really appreciated.

Below code where i got from http://www.mkyong.com/java/how-to-traverse-a-directory-structure-in-java/, but we have to pass some directory as parameter. Is there a way to generalize to get all the locations ?

public static void main (String args[]) {

    displayIt(new File("C:\\"));
}

public static void displayIt(File node){

    System.out.println(node.getAbsoluteFile());

    if(node.isDirectory()){
        String[] subNote = node.list();
        for(String filename : subNote){
            displayIt(new File(node, filename));
        }
}

Upvotes: 0

Views: 2393

Answers (3)

dngfng
dngfng

Reputation: 1943

Apache Commons-IO is a good API for this kind of Operation. For Unix system you could just use root "/" however this will not do for windows, hence you will have to ask for all roots and iterate over them: 

File[] roots = File.listRoots();

Collection<File> files = new ArrayList<File>();    

for(File root : roots) {
    files.addAll(FileUtils.listFiles(
      root, 
      new RegexFileFilter(<your regex filter>), 
      DirectoryFileFilter.DIRECTORY
    ));
}

Upvotes: 3

user902383
user902383

Reputation: 8640

if you want to do this by recursion, here is code for DFS, code might not working (i never test it), and it is not optimized, but it might give you some ideas how to solve your problem

File find(String directoryName, String pattern)
{
 File currentDirectory = loadFile(directoryName);

for (String name: currentDirectory .list())
{
File children = loadFile(name)

if (children.isDirectory())
{
 File file = find(name, pattern)
 if (file !=null)
 {
  return file;
 }
}
else
{
 if (match(name,pattern)
  {
   return children;
  }
}
}
return null;

}

Upvotes: 0

RNJ
RNJ

Reputation: 15552

This sort of code snippet will list all the files in a directory and sub directories. You do not have to add any of the files to allFiles and you could do your check there. As you havent supplied any code yet (so I assume you havent tried anything) I'll let you update it ;)

private void addFiles(File file, Collection<File> allFiles) {
    File[] files = file.listFiles();
    if (files != null) {
       for (File f : files) {
           allFiles.add(f);
           addFiles(f, allFiles);
       }
    }
}

Upvotes: 1

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