What is a safe way to create a Temp file in Java?

java temporary-files
SRobertJames picture SRobertJames · Nov 11, 2014 · Viewed 86k times · Source

I'm looking for a safe way to create a temp file in Java. By safe, I mean the following:

  • Name should be unique, even under potential race conditions (e.g. another Thread calls the same func at the same time, or another process runs this code simultaneously)
  • File should be private, even under potential race conditions (e.g. another user tries to chmod file at high rate)
  • I can tell it to delete the file, without me having to do a generic delete, and risk deleting the wrong file
  • Ideally, should ensure file is deleted, even if exception is thrown before I get the chance to
  • File should default to a sane location (e.g. the JVM specified tmp dir, defaulting to the system temp dir)

Answer

Stefan picture Stefan · Nov 11, 2014

Use File.createTempFile().

File tempFile = File.createTempFile("prefix-", "-suffix");
//File tempFile = File.createTempFile("MyAppName-", ".tmp");
tempFile.deleteOnExit();

Will create a file in the temp dir, like:

prefix-6340763779352094442-suffix

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