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How to delete a directory in java

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A file and directory in java can be deleted by using delete method on java.io.File object which points to the underlying physical file or directory.
delete method will delete a directory only if it is empty otherwise it would not remove the directory.
This post will discuss different methods to delete a non-empty directory in java.
Method 1: Iterative method
Create a java.io.File object which points to the directory to be deleted. Get a list of all files in this directory using listFiles method.
This method returns an array of java.io.File objects each of which represents a file in the directory.
Iterate over the files and in every iteration delete a file. Example,

import java.io.File;

public class DeleteDirectoryExample {
   public static void main(String[] args) {
	String directoryPath = "E:/dummyfolder";
	// create a file object for directory
	File directory = new File(directoryPath);
	// get all files
	File[] files = directory.listFiles();
	// iterate over files
	for (File file : files) {
	   // delete each file
	   file.delete();
	}
	// delete empty directory
	directory.delete();
   }
}

Above method will delete files in a directory till a single level, that is, files that reside directly under the given directory.
If there are sub-folders inside the given directory, then they will not be deleted. For this, use the methods listed below.
Method 2: Recursive method
This method can delete files in the given directory as well as files inside nested folders also. It iterates over the files in the given directory using a loop.
In every iteration, the method checks if the current file object represents a directory or a file. If it is a file, then it is deleted.
If it is a directory, then this method calls itself recursively and iterates over the files in this directory. It continues for nested sub-folders and other folders as well.

import java.io.File;

public class DeleteFileRecursiveExample {
   public static void main(String[] args) {
	String directoryPath = "E:/Test";
	// create a file object for main directory
	File directory = new File(directoryPath);
	// call recursive method
	deleteFile(directory);
   }

   /**
    * Recursive method to delete directory structure
    * @param file
    */
   static void deleteFile(File file) {
	// get all files
	File[] files = file.listFiles();
	// iterate over files
	for (File nestedFile : files) {
	   // check for sub-directory
	   if (nestedFile.isDirectory()) {
               // call this method again
	       deleteFile(nestedFile);
	   } else {
	       // delete each file
	       nestedFile.delete();
	   }
	}
	// check if the directory is empty, then delete it
	if (file.listFiles().length == 0) {
	   file.delete();
	}
   }
}

Method 3: Using Apache Commons Library
Apache Commons Library has a class org.apache.commons.io.FileUtils class for performing file related operations.
This class has a deleteDirectory method which accepts an argument of type java.io.File representing the directory to be deleted and deletes this directory along with its contents.
This method can also be used to delete a complete folder structure consisting of multiple sub-folders and files.

import java.io.File;
import org.apache.commons.io.FileUtils;

public class DeleteFileRecursiveExample {
   public static void main(String[] args) throws IOException {
	String directoryPath = "E:/Test";
	// create a file object for main directory
	File directory = new File(directoryPath);
	FileUtils.deleteDirectory(directory);
   }
}

deleteDirectory method throws a java.io.IOException. You need to throw it or handle it.
Method 4: Using nio java 7
Java 7 introduced java.nio.file.Files class for performing file related operations. This class has a walkFileTree method which accepts below objects as arguments

SimpleFileVisitor class has a method visitFile which is called for each file in the directory or sub-directory and a method postVisitDirectory which is called for every directory.
Both these methods accept a path object as argument representing the file or directory. Thus, visitFile may be used to delete files and postVisitDirectory may be used to delete a directory. Example,

import java.io.File;
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;

public class DirectoryDeleteExample {
   public static void main(String[] args) throws IOException {
      String directoryPath = "E:/Test";
      // create a file object for main directory
      File directory = new File(directoryPath);
      Path path = Paths.get(directoryPath);
      // iterate over the directory
      Files.walkFileTree(path, new SimpleFileVisitor() {
	 // called for each file in the directory
	 @Override
	 public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) 
                  throws IOException {
	   // delete file
	   Files.delete(file);
	   return FileVisitResult.CONTINUE;
	 }

	 // called for each directory
	 @Override
	 public FileVisitResult postVisitDirectory(Path dir, IOException exc) 
                   throws IOException {
	   // delete directory
	   Files.delete(dir);
	   return FileVisitResult.CONTINUE;
         }
      });
   }
}

In the above method, we override(Notice the @Override annotation) the visitFile and postVisitDirectory methods of SimpleFileVisitor as per our requirement.
This method can also be used to delete a directory that contains sub-folders as well.
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