Java: how to create and write to a file

Question

What's the simplest way to create and write to a file in Java?

I know this is a very basic question, but the web is full of different answers for different versions of Java and it would be nice to have an answer here on StackOverflow.

Answer 1

Creating a text file (note that this will overwrite the file if it already exists):

PrintWriter writer = new PrintWriter("the-file-name.txt", "UTF-8");
writer.println("The first line");
writer.println("The second line");
writer.close();

Creating a binary file (will also overwrite the file):

byte dataToWrite[] = //...
FileOutputStream out = new FileOutputStream("the-file-name");
out.write(dataToWrite);
out.close();

Answer 2

Writer writer = null;

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

See also here (includes NIO2)

Answer 3

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

Answer 4

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. Yoda time for date manipulation, 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.

Answer 5

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.