java-how-to-create-a-file

Posted on: 2019-10-08 2019-11-19
Tags: Java IO, Java NIO

Java – Create a File

In this quick tutorial we’re going to learn how to create a new File in Java – first using JDK6, then the newer JDK7 with NIO and finally the Apache Commons IO library.

This article is part of the “Java – Back to Basic” series here on Baeldung.

1. With Java – JDK 6

Let’s start with the standard solution using the old JDK 6 File API:

@Test
public void givenUsingJDK6_whenCreatingFile_thenCorrect() throws IOException {
    File newFile = new File("src/test/resources/newFile_jdk6.txt");
    boolean success = newFile.createNewFile();

    assertTrue(success);
}

Note that the file must not exist for this operation to succeed; if the file does exist, then createNewFile operation will return false.

2. With Java – JDK 7

Let’s now take a look at the newer solution – using the NIO2 support in JDK 7:

@Test
public void givenUsingJDK7nio2_whenCreatingFile_thenCorrect()
  throws IOException {
    Path newFilePath = Paths.get("src/test/resources/newFile_jdk7.txt");
    Files.createFile(newFilePath);
}

As you can see the code is still very simple; we’re now using the new Path interface instead of the old File.

One thing to note here is that the new API makes good use of exceptions – if the file already exists, we no longer have to check a return code – we get a FileAlreadyExistsException instead:

java.nio.file.FileAlreadyExistsException: srctestresourcesnewFile_jdk7.txt
    at sun.n.f.WindowsException.translateToIOException(WindowsException.java:81)

3. With Guava

The Guava solution for creating a new File is a quick one liner as well:

@Test
public void givenUsingGuava_whenCreatingFile_thenCorrect() throws IOException {
    Files.touch(new File("src/test/resources/newFile_guava.txt"));
}

4. With Commons IO

Apache Commons provides the FileUtils.touch() method which implements the same behavior as the “touch” utility in Linux – it creates a new empty file or even a file and full path to it in a file system:

@Test
public void givenUsingCommonsIo_whenCreatingFile_thenCorrect() throws IOException {
    FileUtils.touch(new File("src/test/resources/newFile_commonsio.txt"));
}

Note that this behaves slightly differently than the previous examples – if the file already exists, the operation doesn’t fail – it simply doesn’t do anything.

And there we have it – 4 quick ways to create a new file in Java.

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