code: public static File createTempDirectory(String prefix, String suffix) throws IOException {
  		return createTempDirectory(prefix, suffix, null);
  	}
docs: Create an empty directory in the default temporary-file directory, using
  the given prefix and suffix to generate its name.  Invoking this method
  is equivalent to invoking <code>{@link #createTempDirectory(java.lang.String,
  java.lang.String, java.io.File)
  createTempDirectory(prefix,&nbsp;suffix,&nbsp;null)}</code>.
  
  @param  prefix is the prefix string to be used in generating the file's
  name; must be at least three characters long
  
  @param  suffix is the suffix string to be used in generating the file's
  name; may be <code>null</code>, in which case the
  suffix <code>".tmp"</code> will be used
  @return  An abstract pathname denoting a newly-created empty file
  @throws  IllegalArgumentException
  If the <code>prefix</code> argument contains fewer than three
  characters
  @throws  IOException  If a file could not be created
  @throws  SecurityException
  If a security manager exists and its <code>{@link
  java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
  method does not allow a file to be created
  @since 6.2