Google and Oracle continue to differ over when their lawsuit over alleged Java intellectual property violations in the Android mobile OS should begin, according to a joint filing the companies made late Monday in U.S. District Court for the Northern District of California.

Oracle referred to the "irreparable harm" being caused to Java by "the continued migration of device manufacturers and application developers from Java to Android" in requesting the trial begin on Jan. 20 or 23, after the scheduled Jan. 19 submission of an expert's damages report.

"For instance, Amazon's newly-released Kindle Fire tablet is based on Android, while prior versions of the Kindle were Java-based," Oracle added. "Android has been gaining in other areas as well, with Android-based set-top boxes and even televisions appearing this year. These are markets where Java has traditionally been strong but is now losing ground to Android."

While Google has argued that the number of Java developers actually grew since Oracle filed suit, many of them are focusing on Android and "not for licensed Java implementations," Oracle said.

For its part, Google has "no interest in delaying resolution of this case any longer than necessary," but a January start is not workable given various scheduling issues, the company said in the joint statement. In fact, it may be "difficult to conduct trial before July 2012," Google said.

Oracle's own public figures show that there are 2.5 million more Java developers since the lawsuit was filed, Google added. On one hand, "Oracle contends that many of these developers are writing for Android, with no benefit to Oracle," Google added. "But this is inconsistent with the fact that Oracle touts these figures."

Oracle sued Google in August 2010, alleging that Android violated a number of patents and copyrights it holds on Java, which Oracle gained control of through the acquisition of Sun Microsystems. Google has admitted no wrongdoing.

The court has proposed splitting the trial into a number of phases. While Google is in support of such a move, Oracle has opposed doing so on grounds it would result in redundant testimony.

It's possible that some resolution on the trial's start date and format could come on Wednesday, when the joint filing is discussed at a scheduled pretrial conference.