Creating a Temp Dir in Java

Question

I have a test for a create DB method and I need a temp directory to put it in. The directory will be removed after the test is done. I tried using File.createTempFile(), like so:

tempDir = File.createTempFile("install", "dir");
tempDir.mkdir();

But tempDir is already exists as a file. How do I create a temp directory as opposed to a file?

Answer 1

Well, "createTempFile" actually creates the file. So why not just delete it first, and then do the mkdir on it?

Answer 2

As discussed in this RFE and its comments, you could call tempDir.delete() first. Or you could use System.getProperty("java.io.tmpdir") and create a directory there. Either way, you should remember to call tempDir.deleteOnExit(), or the file won't be deleted after you're done.

Answer 3

This code should work reasonably well:

public static File createTempDir() {
    final String baseTempPath = System.getProperty("java.io.tmpdir");

    Random rand = new Random();
    int randomInt = 1 + rand.nextInt();

    File tempDir = new File(baseTempPath + File.separator + "tempDir" + randomInt);
    if (tempDir.exists() == false) {
        tempDir.mkdir();
    }

    tempDir.deleteOnExit();

    return tempDir;
}