Answer 1

Instead of adding String each other, why don't you create a Arraylist do like following.
It's will be more easy.

ArrayList<String> str=new ArrayList<String>();
String w=""; char ch;
StringTokenizer st= new StringTokenizer(s);
int c=st.countTokens();
for(int i=1;i<=c;i++)
{
w=st.nextToken();
ch=w.charAt(0);
if(ch=='0')
str.add("zero");
if(ch=='1')
str.add("one");
if(ch=='2')
str.add("two");
//And so on
}