count occurences of successive characters of a string

Question

I have a String and I need to count occurances of successive characters of the string.

String s1="aabbcccaaa";

It should print output as

a2b2c3a3

String s1="aabbcccaaa";

char c[]=s1.toCharArray();
StringBuffer sb=new StringBuffer();

LinkedHashMap<Character,Integer> map=new LinkedHashMap<Character,Integer>();




for(int i=0;i<c.length;i++)
{
    Character c1=c[i];
    Integer frequency=map.get(c1);
    map.put(c1, (frequency==null)?1:frequency+1);

    if(map.size()>1 && c[i]!=c[i-1])
    {
        sb.append(c[i-1]+""+map.get(c[i-1]));
        map.remove(c[i-1]);
    }



}
sb.append(map);
System.out.println(sb);

and why exactly should we write whole code for you? at least try it out first — Kumar Saurabh, Sep 02 '15 at 12:57
thanks.. I have tried to iterate the elements and used map to put key as an element and value as its occurance. I am not sure how i can achieve counts if same elements occur again.. — Vivek S, Sep 02 '15 at 13:00
show the code you've done so far, ask specific question where you're stuck and we'll pick it up from there. in general, learn how to use this good site in a constructive manner — Sharon Ben Asher, Sep 02 '15 at 13:00
See also: http://stackoverflow.com/questions/10749176/counting-the-number-of-occurences-of-characters-in-a-string — assylias, Sep 02 '15 at 13:05
Can you check the code and help me how effectively i can do it — Vivek S, Sep 02 '15 at 13:25

Stephen C · Answer 1 · 2015-09-02T13:34:21.580

1

I am not sure how i can achieve counts if same elements occur again.

Hint #1: Test the current character against the previous one.

Hint #2: Ask yourself, why do you need to use a Map?

edited Sep 02 '15 at 13:34

answered Sep 02 '15 at 13:02

Stephen C

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count occurences of successive characters of a string

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