import java.awt.List;import java.util.ArrayList;import java.util.LinkedHashSet;import java.util.LinkedList;import java.util.Set;public class Exercise3 {    public static void main(String[] args){        Set set = new LinkedHashSet();        String string = "aadfsdfdsfdsafafsafsawerewolfasd";        char[] ch = string.toCharArray();        for(int i = 0; i < ch.length; i++){            set.add(ch[i]);        }        System.out.println(set);        ArrayList list = new ArrayList(set);        ArrayList list2 = new ArrayList();        for(int i = 0; i < ch.length; i++){            list2.add(ch[i]);        }        for(int i = 0; i < list.size(); i++){            int n = 0;            for(int j =0; j < list2.size(); j++){                if(list.get(i).equals(list2.get(j))){                    n++;                }            }            System.out.print(list.get(i) + " : " + n + " . ");        }        }    }

//OutPut:

[a, d, f, s, w, e, r, o, l]