How Do I Create a File and Write to It?

In Java 7 and up:

try (Writer writer = new BufferedWriter(new OutputStreamWriter(
              new FileOutputStream("filename.txt"), "utf-8"))) {
   writer.write("something");
}

There are useful utilities for that though:

• FileUtils.writeStringtoFile(..) from commons-io
• Files.write(..) from guava

Note also that you can use a FileWriter, but it uses the default encoding, which is often a bad idea - it's best to specify the encoding explicitly.

Below is the original, prior-to-Java 7 answer

Writer writer = null;

try {
    writer = new BufferedWriter(new OutputStreamWriter(
          new FileOutputStream("filename.txt"), "utf-8"));
    writer.write("Something");
} catch (IOException ex) {
    // Report
} finally {
   try {writer.close();} catch (Exception ex) {/*ignore*/}
}

See also: Reading, Writing, and Creating Files (includes NIO2).

If you already have the content you want to write to the file (and not generated on the fly), the java.nio.file.Files addition in Java 7 as part of native I/O provides the simplest and most efficient way to achieve your goals.

Basically creating and writing to a file is one line only, moreover one simple method call!

The following example creates and writes to 6 different files to showcase how it can be used:

Charset utf8 = StandardCharsets.UTF_8;
List<String> lines = Arrays.asList("1st line", "2nd line");
byte[] data = {1, 2, 3, 4, 5};

try {
    Files.write(Paths.get("file1.bin"), data);
    Files.write(Paths.get("file2.bin"), data,
            StandardOpenOption.CREATE, StandardOpenOption.APPEND);
    Files.write(Paths.get("file3.txt"), "content".getBytes());
    Files.write(Paths.get("file4.txt"), "content".getBytes(utf8));
    Files.write(Paths.get("file5.txt"), lines, utf8);
    Files.write(Paths.get("file6.txt"), lines, utf8,
            StandardOpenOption.CREATE, StandardOpenOption.APPEND);
} catch (IOException e) {
    e.printStackTrace();
}

public class Program {
    public static void main(String[] args) {
        String text = "Hello world";
        BufferedWriter output = null;
        try {
            File file = new File("example.txt");
            output = new BufferedWriter(new FileWriter(file));
            output.write(text);
        } catch ( IOException e ) {
            e.printStackTrace();
        } finally {
          if ( output != null ) {
            try {
                output.close();
            }catch (IOException e){
                e.printStackTrace();
            }
          }
        }
    }
}

A very simple way to create and write to a file in Java:

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;

public class CreateFiles {

    public static void main(String[] args) {
        try{
            // Create new file
            String content = "This is the content to write into create file";
            String path="D:\\a\\hi.txt";
            File file = new File(path);

            // If file doesn't exists, then create it
            if (!file.exists()) {
                file.createNewFile();
            }

            FileWriter fw = new FileWriter(file.getAbsoluteFile());
            BufferedWriter bw = new BufferedWriter(fw);

            // Write in file
            bw.write(content);

            // Close connection
            bw.close();
        }
        catch(Exception e){
            System.out.println(e);
        }
    }
}

Here's a little example program to create or overwrite a file. It's the long version so it can be understood more easily.

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;

public class writer {
    public void writing() {
        try {
            //Whatever the file path is.
            File statText = new File("E:/Java/Reference/bin/images/statsTest.txt");
            FileOutputStream is = new FileOutputStream(statText);
            OutputStreamWriter osw = new OutputStreamWriter(is);    
            Writer w = new BufferedWriter(osw);
            w.write("POTATO!!!");
            w.close();
        } catch (IOException e) {
            System.err.println("Problem writing to the file statsTest.txt");
        }
    }

    public static void main(String[]args) {
        writer write = new writer();
        write.writing();
    }
}

Use:

try (Writer writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("myFile.txt"), StandardCharsets.UTF_8))) {
    writer.write("text to write");
} 
catch (IOException ex) {
    // Handle me
}  

Using try() will close stream automatically. This version is short, fast (buffered) and enables choosing encoding.

This feature was introduced in Java 7.

Here we are entering a string into a text file:

String content = "This is the content to write into a file";
File file = new File("filename.txt");
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
bw.write(content);
bw.close(); // Be sure to close BufferedWriter

We can easily create a new file and add content into it.

Since the author did not specify whether they require a solution for Java versions that have been EoL'd (by both Sun and IBM, and these are technically the most widespread JVMs), and due to the fact that most people seem to have answered the author's question before it was specified that it is a text (non-binary) file, I have decided to provide my answer.

First of all, Java 6 has generally reached end of life, and since the author did not specify he needs legacy compatibility, I guess it automatically means Java 7 or above (Java 7 is not yet EoL'd by IBM). So, we can look right at the file I/O tutorial:

Prior to the Java SE 7 release, the java.io.File class was the mechanism used for file I/O, but it had several drawbacks.

• Many methods didn't throw exceptions when they failed, so it was impossible to obtain a useful error message. For example, if a file deletion failed, the program would receive a "delete fail" but wouldn't know if it was because the file didn't exist, the user didn't have permissions, or there was some other problem.
• The rename method didn't work consistently across platforms.
• There was no real support for symbolic links.
• More support for metadata was desired, such as file permissions, file owner, and other security attributes. Accessing file metadata was inefficient.
• Many of the File methods didn't scale. Requesting a large directory listing over a server could result in a hang. Large directories could also cause memory resource problems, resulting in a denial of service.
• It was not possible to write reliable code that could recursively walk a file tree and respond appropriately if there were circular symbolic links.

Oh well, that rules out java.io.File. If a file cannot be written/appended, you may not be able to even know why.

We can continue looking at the tutorial:

If you have all lines you will write (append) to the text file in advance, the recommended approach is

Here's an example (simplified):

Path file = ...;
List<String> linesInMemory = ...;
Files.write(file, linesInMemory, StandardCharsets.UTF_8);

Another example (append):

Path file = ...;
List<String> linesInMemory = ...;
Files.write(file, linesInMemory, Charset.forName("desired charset"), StandardOpenOption.CREATE, StandardOpenOption.APPEND, StandardOpenOption.WRITE);

If you want to write file content as you go:

Simplified example (Java 8 or up):

Path file = ...;
try (BufferedWriter writer = Files.newBufferedWriter(file)) {
    writer.append("Zero header: ").append('0').write("\r\n");
    [...]
}

Another example (append):

Path file = ...;
try (BufferedWriter writer = Files.newBufferedWriter(file, Charset.forName("desired charset"), StandardOpenOption.CREATE, StandardOpenOption.APPEND, StandardOpenOption.WRITE)) {
    writer.write("----------");
    [...]
}

These methods require minimal effort on the author's part and should be preferred to all others when writing to [text] files.

If you wish to have a relatively pain-free experience you can also have a look at the Apache Commons IO package, more specifically the FileUtils class.

Never forget to check third-party libraries. Joda-Time for date manipulation, Apache Commons Lang StringUtils for common string operations and such can make your code more readable.

Java is a great language, but the standard library is sometimes a bit low-level. Powerful, but low-level nonetheless.

Here are some of the possible ways to create and write a file in Java :

Using FileOutputStream

try {
  File fout = new File("myOutFile.txt");
  FileOutputStream fos = new FileOutputStream(fout);
  BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(fos));
  bw.write("Write somthing to the file ...");
  bw.newLine();
  bw.close();
} catch (FileNotFoundException e){
  // File was not found
  e.printStackTrace();
} catch (IOException e) {
  // Problem when writing to the file
  e.printStackTrace();
}

Using FileWriter

try {
  FileWriter fw = new FileWriter("myOutFile.txt");
  fw.write("Example of content");
  fw.close();
} catch (FileNotFoundException e) {
  // File not found
  e.printStackTrace();
} catch (IOException e) {
  // Error when writing to the file
  e.printStackTrace();
}

Using PrintWriter

try {
  PrintWriter pw = new PrintWriter("myOutFile.txt");
  pw.write("Example of content");
  pw.close();
} catch (FileNotFoundException e) {
  // File not found
  e.printStackTrace();
} catch (IOException e) {
  // Error when writing to the file
  e.printStackTrace();
}

Using OutputStreamWriter

try {
  File fout = new File("myOutFile.txt");
  FileOutputStream fos = new FileOutputStream(fout);
  OutputStreamWriter osw = new OutputStreamWriter(fos);
  osw.write("Soe content ...");
  osw.close();
} catch (FileNotFoundException e) {
  // File not found
  e.printStackTrace();
} catch (IOException e) {
  // Error when writing to the file
  e.printStackTrace();
}

For further check this tutorial about How to read and write files in Java .

If you for some reason want to separate the act of creating and writing, the Java equivalent of touch is

try {
   //create a file named "testfile.txt" in the current working directory
   File myFile = new File("testfile.txt");
   if ( myFile.createNewFile() ) {
      System.out.println("Success!");
   } else {
      System.out.println("Failure!");
   }
} catch ( IOException ioe ) { ioe.printStackTrace(); }

createNewFile() does an existence check and file create atomically. This can be useful if you want to ensure you were the creator of the file before writing to it, for example.

Use:

JFileChooser c = new JFileChooser();
c.showOpenDialog(c);
File writeFile = c.getSelectedFile();
String content = "Input the data here to be written to your file";

try {
    FileWriter fw = new FileWriter(writeFile);
    BufferedWriter bw = new BufferedWriter(fw);
    bw.append(content);
    bw.append("hiiiii");
    bw.close();
    fw.close();
}
catch (Exception exc) {
   System.out.println(exc);
}

best way is to use Java7: Java 7 introduces a new way of working with the filesystem, along with a new utility class – Files. Using the Files class, we can create, move, copy, delete files and directories as well; it also can be used to read and write to a file.

public void saveDataInFile(String data) throws IOException {
    Path path = Paths.get(fileName);
    byte[] strToBytes = data.getBytes();

    Files.write(path, strToBytes);
}

Write with FileChannel If you are dealing with large files, FileChannel can be faster than standard IO. The following code write String to a file using FileChannel:

public void saveDataInFile(String data) 
  throws IOException {
    RandomAccessFile stream = new RandomAccessFile(fileName, "rw");
    FileChannel channel = stream.getChannel();
    byte[] strBytes = data.getBytes();
    ByteBuffer buffer = ByteBuffer.allocate(strBytes.length);
    buffer.put(strBytes);
    buffer.flip();
    channel.write(buffer);
    stream.close();
    channel.close();
}

Write with DataOutputStream

public void saveDataInFile(String data) throws IOException {
    FileOutputStream fos = new FileOutputStream(fileName);
    DataOutputStream outStream = new DataOutputStream(new BufferedOutputStream(fos));
    outStream.writeUTF(data);
    outStream.close();
}

Write with FileOutputStream

Let’s now see how we can use FileOutputStream to write binary data to a file. The following code converts a String int bytes and writes the bytes to file using a FileOutputStream:

public void saveDataInFile(String data) throws IOException {
    FileOutputStream outputStream = new FileOutputStream(fileName);
    byte[] strToBytes = data.getBytes();
    outputStream.write(strToBytes);

    outputStream.close();
}

Write with PrintWriter we can use a PrintWriter to write formatted text to a file:

public void saveDataInFile() throws IOException {
    FileWriter fileWriter = new FileWriter(fileName);
    PrintWriter printWriter = new PrintWriter(fileWriter);
    printWriter.print("Some String");
    printWriter.printf("Product name is %s and its price is %d $", "iPhone", 1000);
    printWriter.close();
}

Write with BufferedWriter: use BufferedWriter to write a String to a new file:

public void saveDataInFile(String data) throws IOException {
    BufferedWriter writer = new BufferedWriter(new FileWriter(fileName));
    writer.write(data);

    writer.close();
}

append a String to the existing file:

public void saveDataInFile(String data) throws IOException {
    BufferedWriter writer = new BufferedWriter(new FileWriter(fileName, true));
    writer.append(' ');
    writer.append(data);

    writer.close();
}

This answer is centred on Java 8, and tries to cover all the details needed for the Java Professional Exam. It tries to explain why the different approaches exist. They each have their benefits, and each might be simplest in a given scenario.

Classes involved include:

.
├── OutputStream
│   └── FileOutputStream
├── Writer
│   ├── OutputStreamWriter
│   │   └── FileWriter
│   ├── BufferedWriter
│   └── PrintWriter (Java 5+)
└── Files (Java 7+)

FileOutputStream

This class is meant for writing streams of raw bytes. All the Writer approaches below rely on this class, either explicitly or under the hood.

try (FileOutputStream stream = new FileOutputStream("file.txt");) {
    byte data[] = "foo".getBytes();
    stream.write(data);
} catch (IOException e) {}

Note that the try-with-resources statement takes care of stream.close() and that closing the stream flushes it, like stream.flush() (all of the examples below use this approach).