STRING Compr

public class SmjerD {

    public static String compr(String a)
    {
        char zn,nn;
        int br;
        String rez="";
        int l=a.length();
        for(int i=0;i<l-1;i++)
        {
            zn=a.charAt(i);
            nn=a.charAt(i+1);
            br=1;
            while (nn==zn)
            {
                br++;
                if (i<l-2)
                {
                    i++;
                    nn=a.charAt(i+1);
                }
                else break;
            }
            if(br==1) rez=rez+zn;
            else rez=rez+br+zn;
        }

        zn=a.charAt(l-2);
        nn=a.charAt(l-1);
        if(zn!=nn) rez=rez+nn;

        return rez;

    }



    public static String PetarCompr(String s)
    {
        String s1 = "";
        int br, pocetak = 0, probni;
        while(pocetak<s.length())
        {
            br = 1;
            probni = pocetak + 1;
            if(probni<s.length()-2)
            {
                while(s.charAt(pocetak)==s.charAt(probni))
                {
                    probni++;
                    br++;
                }
                if(br>1)
                {
                    s1+= br + "" + s.charAt(pocetak);
                }
                else
                {
                    s1+= s.charAt(pocetak);
                }
            }
            else
            {
                s1+= s.charAt(pocetak);
            }
            pocetak = probni;
        }
        return s1;
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        String s2= new String ("BBB222222XXKKK");
        String s3="MEePPAAAAAkLLLa";
        String s4="YXxXXCVB";


        System.out.println(compr(s2));
        System.out.println(compr(s3));
        System.out.println(compr(s4));
        System.out.println(PetarCompr(s2));
        System.out.println(PetarCompr(s3));
        System.out.println(PetarCompr(s4));
    }

}