Android tabHost accessing specific tabs

I have a tabHost with tree tabs. How can I access a specific tab from the tabHost activity when this tab is not active at the moment. And a second question to this topic..开发者_JS百科. How can I access the activity of a tab from another tab?

I need this, because I have to update the second tab when something changes on the first tab.

Thank you

This is it:

mTabHost.getTabWidget().getChildAt(2)