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

Answer 1

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
public class DuplicateCountChar{

    public static void main(String[] args) {
        Scanner inputString = new Scanner(System.in);
        String token = inputString.nextLine();
        char[] ch = token.toCharArray();
        Map<Character, Integer> dupCountMap =  new HashMap<Character,Integer>();

        for (char c : ch) {
            if(dupCountMap.containsKey(c)) { 
                dupCountMap.put(c, dupCountMap.get(c)+1);
            }else {
                dupCountMap.put(c, 1);
            }
        }


        for (char c : ch) {
            System.out.println("Key = "+c+ "Value : "+dupCountMap.get(c));
        }

        Set<Character> keys = dupCountMap.keySet();
        for (Character character : keys) {
            System.out.println("Key = "+character+ " Value : " + dupCountMap.get(character));
        }

    }**

Answer 2

public static void main(String[] args) {
        char[] array = "aabsbdcbdgratsbdbcfdgs".toCharArray();
        char[][] countArr = new char[array.length][2];
        int lastIndex = 0;
        for (char c : array) {
            int foundIndex = -1;
            for (int i = 0; i < lastIndex; i++) {
                if (countArr[i][0] == c) {
                    foundIndex = i;
                    break;
                }
            }
            if (foundIndex >= 0) {
                int a = countArr[foundIndex][1];
                countArr[foundIndex][1] = (char) ++a;
            } else {
                countArr[lastIndex][0] = c;
                countArr[lastIndex][1] = '1';
                lastIndex++;
            }
        }
        for (int i = 0; i < lastIndex; i++) {
            System.out.println(countArr[i][0] + " " + countArr[i][1]);
        }
    }

Answer 3

public class dublicate 
{
public static void main(String...a)
{
    System.out.print("Enter the String");
    Scanner sc=new Scanner(System.in);
    String st=sc.nextLine();
    int [] ar=new int[256];
    for(int i=0;i<st.length();i++)
    {
        ar[st.charAt(i)]=ar[st.charAt(i)]+1;
    }
    for(int i=0;i<256;i++)
    {
        char ch=(char)i;
        if(ar[i]>0)
        {
            if(ar[i]==1)
            {
                System.out.print(ch);
            }
            else
            {
                System.out.print(ch+""+ar[i]);
            }
        }
    }

}
}

Answer 4

  public class StringCountwithOutHashMap {
  public static void main(String[] args) {
    System.out.println("Plz Enter Your String: ");
    Scanner sc = new Scanner(System.in);
    String s1 = sc.nextLine();
    int count = 0;
    for (int i = 0; i < s1.length(); i++) {
        for (int j = 0; j < s1.length(); j++) {
            if (s1.charAt(i) == s1.charAt(j)) {
                count++;
            } 
        } 
        System.out.println(s1.charAt(i) + " --> " + count);
        String d = String.valueOf(s1.charAt(i)).trim();
        s1 = s1.replaceAll(d, "");
        count = 0;
    }}}

Answer 5

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 6

Use google guava Multiset<String>.

Multiset<String> wordsMultiset = HashMultiset.create();
wordsMultiset.addAll(words);
for(Multiset.Entry<E> entry:wordsMultiset.entrySet()){
     System.out.println(entry.getElement()+" - "+entry.getCount());
}