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This noncompliant code example invokes the File.createTempFile() method, which generates a unique temporary file name based on two parameters, a prefix and an extension. This is the only method from Java 6 and earlier that is designed to produce unique file names, although the names produced can be easily predicted. A random number generator can be used to produce the prefix if a random file name is required.

Wiki MarkupThis example also uses the {{deleteOnExit()}} method to ensure that the temporary file is deleted when the Java Virtual Machine (JVM) terminates. However, according to the Java API \ [[API 2006|AA. References#API 06] \] Class {{File}}, method {{deleteOnExit()}} documentation,

Deletion will be attempted only for normal termination of the virtual machine, as defined by the Java Language Specification. Once deletion has been requested, it is not possible to cancel the request. This method should consequently be used with care.
Note: this method should not be used for file-locking, as the resulting protocol cannot be made to work reliably.

Wiki MarkupConsequently, the file is not deleted if the JVM terminates unexpectedly. A longstanding bug on Windows-based systems reported as [Bug ID: 4171239|http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4171239] \ [[SDN 2008|AA. References#SDN 08] \] causes JVMs to fail to delete a file when {{deleteOnExit()}} is invoked before the associated stream or {{RandomAccessFile}} is closed.

class TempFile {
  public static void main(String[] args) throws IOException{
    File f = File.createTempFile("tempnam",".tmp");
    FileOutputStream fop = null;
    try {
      fop = new FileOutputStream(f);
      String str = "Data";
      fop.write(str.getBytes());
      fop.flush();
    } finally {
      // Stream/file still open; file will
      // not be deleted on Windows systems
      f.deleteOnExit(); // Delete the file when the JVM terminates

      if (fop != null) {
        try {
          fop.close();
        } catch (IOException x) {
          // handle error
        }
      }
    }
  }
}

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Bibliography

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      12. Input Output (FIO)