Removed unused code
Removed unused code OnChildClickListener mExpandableListListener
Removed unused code ColorStateList oldColor
Removed unused tag
Removed unused imports
Fix Implicitly using the default locale is a common source of bugs: Use toLowerCase(Locale) instead
Fix not using locale for String.format
fix To get local formatting use getDateInstance(), getDateTimeInstance(), or getTimeInstance(), or use new SimpleDateFormat(String template, Locale locale) with for example Locale.US for ASCII dates.