Android, how to populate a CharSequence array dynamically (not initializing?)

Use a List object to manage items and when you have all the elements then convert to a CharSequence. Something like this:

List<String> listItems = new ArrayList<String>();

listItems.add("Item1");
listItems.add("Item2");
listItems.add("Item3");

final CharSequence[] charSequenceItems = listItems.toArray(new CharSequence[listItems.size()]);

You are almost there. You need to allocate space for the entries, which is automatically done for you in the initializing case above.

CharSequence cs[];

cs = new String[2];

cs[0] = "foo"; 
cs[1] = "bar"; 

Actually CharSequence is an Interface and can thus not directly be created, but String as one of its implementations can.

You can also use List, to have a dynamic number of members in the array(list :)):

List<CharSequence>  cs = new ArrayList<CharSequence>();

cs.add("foo"); 
cs.add("bar"); 

If you want to use array, you can do:

CharSequence cs[];

cs = new String[2];

cs[0] = "foo"; 
cs[1] = "bar";