How to create new file inside directory in Java?



Problem Description :


Write a program in Java that creates a new file inside a given directory.

Java program that creates a new file in given directory.
Create new file in given directory in Java


Concept
:


We can solve this problem with the help of mkdir() and createNewFile() methods of File class that is present in java.io package. We will use following two constructors of File class to create file class instance.
                                             File file=new File(directorypath);
            File file=new File(directoryname,filename);


Algorithm :


  1. Validate drive letter and file name. Drive letter should be character and file name should have proper extension, for example - .txt, .pdf, .doc etc.
  2. Check whether given directory already exists in given drive or not? 
  3. If directory exists then no need to create new directory otherwise create directory.
  4. Check whether given file exists in given directory or not?
  5. If file exists then no need to create new file otherwise create file.

Java Program :


package com.javamultiplex.filehandling;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.InputMismatchException;
import java.util.Scanner;

/**
 * 
 * @author Rohit Agarwal
 * @category File Handling
 * @problem How to create new file in given directory?
 * 
 */
public class CreateFileInDirectory {

 public static void main(String[] args) throws IOException {

  Scanner input = null;
  BufferedReader br = null;

  try {
   boolean result = false;
   input = new Scanner(System.in);
   br = new BufferedReader(new InputStreamReader(System.in));
   System.out.println("Enter drive letter : ");
   char ch = input.next(".").charAt(0);
   System.out.println("Enter directory name : ");
   String directoryName = br.readLine();
   System.out.println("Enter file name with extension : ");
   String fileName = br.readLine();
   if (isValidFileName(fileName)) {
    result = createNewFile(ch, directoryName, fileName);
    if (result) {
     System.out.println("File " + fileName + " successfully created in directory " + ch + ":\\" + directoryName);
    }
   } else {
    System.out.println("Enter file name correctly!");
   }
  } catch (InputMismatchException e) {
   System.out.println("Enter drive letter correctly!");
  } finally {
   if (input != null) {
    input.close();
   }
   if (br != null) {
    br.close();
   }
  }
 }

 private static boolean createNewFile(char ch, String directoryName, String fileName) {

  // Creating File reference.
  File directory = new File(ch + ":\\" + directoryName);

  // If directory doesn't exist then creating a new directory.
  if (!directory.exists()) {
   directory.mkdir();
  }
  // Creating File reference.
  File file = new File(directory, fileName);
  boolean result = false;
  // Checking whether file exist or not in given path.
  if (file.exists()) {
   System.out.println("File " + fileName + " already exist in directory " + ch + ":\\" + directoryName);
  } else {
   try {
    result = file.createNewFile();
   } catch (IOException e) {
    System.out.println("Error occured in creating new file.\n" + e.getMessage());
   }

  }
  return result;
 }

 private static boolean isValidFileName(String fileName) {

  String pattern = "^.+\\..+$";
  boolean result = false;
  if (fileName.matches(pattern)) {
   result = true;
  }
  return result;
 }

}

Output :


Output of Java program that creates a new file in given directory.
Output - How to create a new file in given directory in Java?

After the execution of above program
given file is present in given directory.
file "demo.txt" in directoy "E:\javamultiplex"

References :


https://docs.oracle.com/javase/7/docs/api/java/io/File.html#exists()

https://docs.oracle.com/javase/7/docs/api/java/io/File.html#mkdir()


https://docs.oracle.com/javase/7/docs/api/java/io/File.html#createNewFile()

https://docs.oracle.com/javase/7/docs/api/java/lang/String.html


https://en.wikipedia.org/wiki/Regular_expression


Thank you friends, I hope you have clearly understood the solution of this problem. If you have any doubt, suggestion or query please feel free to comment below. You can also discuss this solution in our forum.

Tags : File Handling, Create new file in directory, if else, Scanner, BufferedReader, File, String, Regular Expressions, InputStreamReader, java.io, mkdir(), exists(), createNewFile().

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How to create new file inside directory in Java? How to create new file inside directory in Java? Reviewed by Rohit Agarwal on 3/30/2017 Rating: 5

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