Java Program to Create File

In Java, we can create a file either in the current working directory or in some other location. Similar to the file we are also able to create a directory in the current working directory or in some other given location. Different methods to create file or directory are,

Return Type	Method	Description
boolean	createNewFile() throws IOException	It creates an empty normal file with the given name in given path.
boolean	mkdir()	It creates a directory with given name in the given path.
boolean	mkdirs()	It creats both parent and child directories with given names in the given path.

In the above methods, If the file/directory already exists in the given path then it returns false else it returns true and creates the file/directory with a given name. The createNewFile() method throws IOException when an I/O error occurs. All three methods throw SecurityException if the security manager exists and does not permit the named directory to be created.

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Java create file using createNewFile() method

The createNewFile() method is given in the java.io.File class to create file either in current working directory or in some other location.

Method prototype:- public boolean createNewFile() throws IOException

If the file already exists in the folder than createNewFile() method returns false else it returns true and creates an empty file with the given name in the given path. It throws IOException if an I/O error occurs and throws SecurityException if a security manager exists.

Java program to create file in current directory

To create the file in the current working directory the following constructor is used:- File(String path name). See all constructors of java.io.File class

import java.io.File;
import java.io.IOException;

public class FileCreationInCurrentDir {
   public static void main(String[] args) {

      try {
         // creating file object
         File f1 = new File("abc.txt");

         // create new file with given name
         boolean flag = f1.createNewFile();
         
         // display message
         if(flag) {
            System.out.println("File created.");
            System.out.println("f1: "+f1);
         } else {
            System.out.println("File/directory already exist");
         }
  
      } catch (IOException ioe) {
         ioe.printStackTrace();
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

The output of first-time execution:-

File created.
f1: abc.txt

The output of second-time execution:-

File/directory already exist

When we execute the above program for the first time, at that time “abc.txt” file is not exist is in the current directory so, createNewFile() method creates the file. Later when we execute the same program for the second time, then the “abc.txt” file already exists in the current directory. Hence, it will not create again and return false. The createNewFile() method throws IOException so, it is a better idea to catch those exceptions.

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Create different types of empty files

Using createNewFile() method we can create files with different extensions, but those files will be empty. The createNewFile() method of java.io.File is used for creating empty files.

import java.io.File;
import java.io.IOException;

public class DifferentFileCreation {
   public static void main(String[] args) {

      try {

         File file1 = new File("HelloWorld.java");
         System.out.println(file1.createNewFile());
         System.out.println("file1: "+file1);

         File file2 = new File("program.pdf");
         System.out.println(file2.createNewFile());
         System.out.println("file2: "+file2);

         File file3 = new File("hello.class");
         System.out.println(file3.createNewFile());
         System.out.println("file3: "+file3);

         File file4 = new File("index.html");
         System.out.println(file4.createNewFile());
         System.out.println("file4: "+file4);

         File file5 = new File("image.png");
         System.out.println(file5.createNewFile());
         System.out.println("file5: "+file5);
         
      } catch (IOException ioe) {
         ioe.printStackTrace();
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

Output on first run:-

true
file1: HelloWorld.java
true
file2: program.pdf
true
file3: hello.class
true
file4: index.html
true
file5: image.png

The above program creates HelloWorld.java, program.pdf, hello.class, index.html, and image.png files in the current working directory. When we execute this program for the second time than it won’t create new files because they already exist, this time createNewFile() method returns false. Note that all the created files are empty files.

In this program we have hardcoded the names of the files for understanding purposes, you can read the names of the files dynamically from the end-user. We can use OuputStream classes or Writer class to insert the data in these files.

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Java mkdir() method to create directory

We can also create a file inside a directory. To create a file inside a directory first we should learn how to create a directory. To create a directory mkdir() method is given in the File class.

We can use the following constructors:-
public File(String parent, String child)
public File(File parent, String child)

import java.io.File;
import java.io.IOException;

public class CreateFileDirectory {
   public static void main(String[] args) {

      // create directory
      File dir1 = new File("directory1");
      System.out.println(dir1.mkdir());
      System.out.println("dir1: "+ dir1);

      try {
         // create file inside "directory1"
         File f = new File(dir1,"program.java");
         System.out.println(f.createNewFile());
         System.out.println(f);

      } catch(IOException ioe) {
         ioe.printStackTrace();
      } catch(Exception e) {
         e.printStackTrace();
      }
   }
}

Output on run1:-

true
dir1: directory1
true
directory1\program.java

Output on run2:-

false
dir1: directory1
false
f: directory1\program.java

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Java mkdirs() method to create directories

We can create two directories at a time. For this purpose mkdirs() method is given in the java.io.File class.

import java.io.File;
import java.io.IOException;

public class CreateMultipleDirectory {
   public static void main(String[] args) {

      // creating directories
      File f1 = new File("dirX","dirY");
      System.out.println(f1.mkdirs());
      System.out.println("f1: "+f1);

      // creating directories when 
      // parent directory is already exist
      File f2 = new File("dirX","dirZ");
      System.out.println(f2.mkdirs());
      System.out.println("f2: "+f2);

      try {
         // creating files in the child directories
         File f3 = new File(f1, "1.txt");
         f3.createNewFile();
         System.out.println("f3: "+f3);

         File f4 = new File(f2, "2.txt");
         f4.createNewFile();
         System.out.println("f4: "+f4);

      } catch(IOException ioe) {
         ioe.printStackTrace();
      } catch(Exception e) {
         e.printStackTrace();
      }
   }
}

Output on run1:-

true
f1: dirX\dirY
true
f2: dirX\dirZ
f3: dirX\dirY\1.txt
f4: dirX\dirZ\2.txt

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Java program with all methods

Java program to demonstrate createNewFile(), mkdir() and mkdirs() methods,

import java.io.File;
import java.io.IOException;

class CreateFileParentDirectory {
   public static void main(String[] args) {

      try {
         // creating files
         File f1 = new File("abc.txt");
         f1.createNewFile();
         System.out.println("f1: "+f1);

         // creating directory
         File f2 = new File("dir1");
         f2.mkdir();
         System.out.println("f2: "+f2);

         // Creating files inside directory
         File f3 = new File(f2,"program.java");
         f3.createNewFile();
         System.out.println("f3: "+f3);

         // creating parent and child directories
         File f4 = new File("dir2","dir3");
         f4.mkdirs();
         System.out.println("f4: "+f4);

         // creating child directory 
         // when parent is already exist 
         File f5 = new File("dir2","dir4");
         f5.mkdirs();
         System.out.println("f5: "+f5);

      } catch(IOException ioe) {
         ioe.printStackTrace();
      } catch(Exception e) {
         e.printStackTrace();
      }
   }
}

Output:-

f1: abc.txt
f2: dir1
f3: dir1\program.java
f4: dir2\dir3
f5: dir2\dir4

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