Find duplicate characters in a String and count the number of occurances using Java

Question

How can I find the number of occurrences of a character in a string?

For example: The quick brown fox jumped over the lazy dog.

Some example outputs are below,

'a' = 1
'o' = 4
'space' = 8
'.' = 1

Answer 1

Java 8 way:

"The quick brown fox jumped over the lazy dog."
        .chars()
        .mapToObj(i -> (char) i)
        .collect(Collectors.groupingBy(Object::toString, Collectors.counting()));

Answer 2

Finding the duplicates in a String:

Example 1 : Using HashMap

public class a36 {
    public static void main(String[] args) {
        String a = "Gini Rani";
        fix(a);
    }//main
    public static void fix(String a ){
        Map<Character ,Integer> map = new HashMap<>();
        for (int i = 0; i <a.length() ; i++ ) {
        char ch = a.charAt(i);
                map.put(ch , map.getOrDefault(ch,0) +1 );
        }//for

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

       for (  Map.Entry<Character ,Integer> entry : entrySet) {
             list.add( entry.getKey()  ); 

             System.out.printf(  " %s : %d %n" ,  entry.getKey(), entry.getValue()           );
       }//for
       System.out.println("Duplicate elements => " + list);

    }//fix
}

Example 2 : using Arrays.stream() in Java 8

public class a37 {
    public static void main(String[] args) {
        String aa = "Protijayi Gini";
        String[] stringarray = aa.split("");

    Map<String , Long> map =  Arrays.stream(stringarray)
        .collect(Collectors.groupingBy(c -> c , Collectors.counting()));
        map.forEach( (k, v) -> System.out.println(k + " : "+ v)        );
    }
}