Java SimpleFileVisitor traverse file systems

Introduction

The enumeration constants for the enumeration FileVisitResult are listed as follows:

Value Meaning
CONTINUE Continue the traversal
SKIP_SIBLINGSContinue without visiting the siblings of this file or directory
SKIP_SUBTREE Continue without visiting the entries in this directory
TERMINATETerminate 
import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;

class ListFiles extends SimpleFileVisitor<Path> {
   private final int indentionAmount = 3;
   private int indentionLevel;

   public ListFiles() {
      indentionLevel = 0;//w  w w  . jav a2 s  .c  o  m
   }

   private void indent() {
      for (int i = 0; i < indentionLevel; i++) {
         System.out.print(' ');
      }
   }

   @Override
   public FileVisitResult visitFile(Path file, BasicFileAttributes attributes) {
      indent();
      System.out.println("Visiting file:" + file.getFileName());
      return FileVisitResult.CONTINUE;
   }

   @Override
   public FileVisitResult postVisitDirectory(Path directory, IOException e) throws IOException {
      indentionLevel -= indentionAmount;
      indent();
      System.out.println("Finished with the directory: " + directory.getFileName());
      return FileVisitResult.CONTINUE;
   }

   @Override
   public FileVisitResult preVisitDirectory(Path directory, BasicFileAttributes attributes) throws IOException {
      indent();
      System.out.println("About to traverse the directory: " + directory.getFileName());
      indentionLevel += indentionAmount;
      return FileVisitResult.CONTINUE;
   }

   @Override
   public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException {
      System.out.println("A file traversal error ocurred");
      return super.visitFileFailed(file, exc);
   }
}

public class Main {

   public static void main(String[] args) {
      try {
         Path path = Paths.get("/home");
         ListFiles listFiles = new ListFiles();
         Files.walkFileTree(path, listFiles);
      } catch (IOException ex) {
         ex.printStackTrace();
      }
   }
}



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