Count Duplicate letters

Question

I want to get a string count any letter in the string how many time it's appeared in the string,and print the letter and the number So that what i did:

import java.util.Scanner;
public class test1 {
public static void main(String[] args) {
    String str;
    Scanner in = new Scanner(System.in);
    System.out.println("enter name");
    str = in.nextLine();
    char[] c1 = str.toCharArray();
    int[] f = new int[str.length()];
    for(int i=0;i<str.length();i++) {
        for(int j=0;j<str.length();j++) {
            if(c1[i]==c1[j]) {
                f[i]++;
            }
        }
    }
    for(int k=0;k<c1.length;k++) {
        for(int l=0;l<c1.length;l++) {
            if(c1[k]==c1[l]) {
                if(l!=k) {c1[k]=0;f[k]=0;}
            }
        }
        System.out.println(c1[k]+"="+f[k]);
    }
}
}

There are two problems:
1. when i print it's printing the duplicated letter twice(or thrice or more depends how many times the letter is in the string). so i added the another 2 loops(k and l) that deletes the duplicated letters,but now instead of the duplicated letter it's print me: an square and a zero,how i can just get delete the letter and the number from the char and int array's?(for example when i insters the name "elichai" i get:

e=1
l=1
(an square)=0
c=1
h=1
a=1
i=2

2.The letter it deletes is the second letter not the first
(in "elichai" example it's deleted the first 'i' instead of the second 'i') Thanks!

[How do I count the number of occurrences of a char in a String?](http://stackoverflow.com/q/275944/334274) — Jivings, Jan 29 '13 at 19:54

jlordo · Accepted Answer · 2013-01-29T20:54:43.593

7

Different approach to solve your problem, but this is how I would probably do it:

String input = "Whatever";
Map<Character, Integer> charCounter = new LinkedHashMap<>(); // respects insertion order
for (char c : input.replaceAll("\\s+", "").toCharArray()) { // ignore spaces
    Integer count = charCounter.get(c);
    count = count == null ? 0 : count;
    charCounter.put(c, count + 1);
}
System.out.println(charCounter);

edited Jan 29 '13 at 20:54

answered Jan 29 '13 at 19:56

jlordo

37,490
6
58
83

can you please explain what you did?(i never seen that kind of a for loop).And one last thing i need it in the right order and what you did mixing the order(it's print the 'v' letter first instead of the 'w').Thanks! – elichai2 Jan 29 '13 at 20:22
@elichai2: Look at the change of the code `LinkedHashMap` instead of `HashMap`. Search for enhanced for loop, e.g. [here](http://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html) – jlordo Jan 29 '13 at 20:26
One last thing,how can i tell it to ignore spaces? (I tried: if(charCounter.get(c)==' '){count=null;} Or: if(charCounter.get(c)==' '){count=0;} And it didn't worked) Thanks! – elichai2 Jan 29 '13 at 20:48
@elichai2: see the code edit, to ignore (all kinds of) spaces. – jlordo Jan 29 '13 at 20:55
what is that line: "count = count == null ? 0 : count;" ? – elichai2 Jan 29 '13 at 21:11
1

`?` is the conditional operator. `a ? b : c` means if `a` is true, it will evaluate to `b`, else `c`. It needs to be done here, because when we encounter a character for the first time `charCounter.get(c);` will return `null` (as it was not put in the map before). – jlordo Jan 29 '13 at 21:16

score 0 · Answer 2 · edited Sep 28 '14 at 13:42

0

class Twice_Occuring
{
    void main(String s)
    {
        int count=0;
        for(int i=0;i<s.length();i++)
        {
            char c=s.charAt(i);
            int ind1=s.indexOf(c,i);
            int ind2=s.indexOf(c,i+1);
            if(ind2-ind1==1)
            {System.out.print(c+" ");count++;}
        }
        System.out.println("\n Number of counts = "+count);
    }
}

edited Sep 28 '14 at 13:42

lennon310

12,503
11
43
61

answered Sep 28 '14 at 13:37

Harish

1

Count Duplicate letters

2 Answers2