I have an android cell phone and an ipad. Do I need both a converter and an adapter plug for anywhere in China?
Adapter Plug is all you need. But many business class hotels in China have USB jacks and/or US style electrical outlets installed inside the room so may not even need an adapter in the end.
China is 220 volts. Your devices should be 110-220 volts so a converter is not necessary. Check your owner's manual.
Your plug (assuming you are from North America or Europe) may work because most places in China have multiple outlets that can take different international plugs. The safe bet is to get a "type l" plug adapter. You can find them in dollar stores or buy them in China (where they are all probably made).