Java List question

Question

I have a program like this

public class no_of_letters_count {
static int i;
 public static void main(String[] args) 
 {

  String sMessage="hello how r u";
  String saMessage[] = sMessage.split("");
  List sList = Arrays.asList(saMessage);                  
  Collections.sort(sList);
  Iterator i=sList.iterator();
  while (i.hasNext())
  {
   System.out.println((String)i.next());
  }
 }
}

//Now i want to count the number of occurance of each characters.

Like

Count of h=2

Count of e=1

and so on

Answer 1

Iterate over sList and put each char in a HashMap. If it doesn't exists start with count 1, otherwise increment the count.

EDIT : Cannot help posting some code.

First of all, use gnerics.

List<Character> sList = Arrays.asList(saMessage.toCharArray()); 

Then use the following map :

Map<Character, Integer> cmap = new HashMap<Character, Integer>();

Answer 2

Using commons-collections and commons-lang

List<Character> chars = Arrays.asList(
     ArrayUtils.toObject("asdfasdas".toCharArray()));
Bag bag = new HashBag(chars);

System.out.println(bag.getCount('a'));

Answer 3

Here are some hints:

It seems you are just trying to get the chars in a String. Use String.toCharArray().

Use a Map<Character,Integer> to store the chars and it's occurrences:

foreach char c in sMessage.ToCharArray()
if map.containsKey(c)
  map.put(c, map.get(c) + 1);
else
  map.put(c, 1);

Next sort the map and present the results. I leave you here a snippet to sort the map:

    List<Entry<Character,Integer>> l = new ArrayList<Entry<Character,Integer>>(map.entrySet());

    Collections.sort(l, new Comparator<Entry<Character,Integer>>() {
        public int compare(Entry<Character, Integer> o1, Entry<Character, Integer> o2) {
            return o1.getKey().compareTo(o2.getKey());
        }
    });

Answer 4

Prints number of occurrences of characters from A-Z and a-z

Note: using the character as array index, not safe if you have Unicode chars :), but still good idea i think!!

String str = "sometext anything";
int[] array=new int[256];

for (int x:array) array[x]=0;

for (char c:str.toCharArray()){
    array[c]++;
}

for (int i=65;i<=90; i++){
    System.out.println("Number of "+(char)i+ "="+array[i]
                + ", number of "+(char)(i+32)+"="+ array[i+32]);
}