Change StringTokenizer to TextUtils.StringSplitter

Replacing StringTokenizer to TextUtils.StringSplitter,
since TextUtils.StringSplitter is more suitable for basic splitting tasks.
Also increased initial values for HashMap and StringBuilders to avoid
unnecessary buffer enlargement operations. This improves the performance
of these operations.

Change-Id: If9a5b68e6596ba9a6d29597876b6164ef34b57ac