How to use ASCII in array

Question

I want to write a program that takes a string text, counts the appearances of every letter in English and stores them inside an array.and print the result like this:

java test abaacc
a:***
b:*
c:**

* - As many time the letter appears.

public static void main (String[] args)  {
   String input = args[0];
   char [] letters = input.toCharArray();
   System.out.println((char)97);
   String a = "a:";
   for (int i=0; i<letters.length; i++) {
      int temp = letters[i];
      i = i+97;
      if (temp == (char)i) {
         temp = temp + "*";
      }
      i = i - 97;
   }
   System.out.println(temp);
}

So make an array of size how many letter in alphabet (26?) and then increment that index by 1 every time such a letter appears — 3kings
– 3kings, Commented Nov 13, 2015 at 21:56
is it case sensitive, e.g. count 'A' and 'a' separately? As @3kings said, you can have an array, indexed by the letter's position in the array. You can quickly compute this index by subtracting the ascii values, e.g. 'g' - 'a' will give you 6. If case insensitive, you will need to convert to lower case, or if letter is uppercase, subtract 'A' from it. If case sensitive, you will need an array twice as big, and figure out where to put them. — DBug
– DBug, Commented Nov 13, 2015 at 22:11

Andreas · Accepted Answer · 2015-11-13 22:13:41Z

2

Writing (char)97 makes the code less readable. Use 'a'.

As 3kings said in a comment, you need an array of 26 counters, one for each letter of the English alphabet.

Your code should also handle both uppercase and lowercase letters.

private static void printLetterCounts(String text) {
    int[] letterCount = new int[26];
    for (char c : text.toCharArray())
        if (c >= 'a' && c <= 'z')
            letterCount[c - 'a']++;
        else if (c >= 'A' && c <= 'Z')
            letterCount[c - 'A']++;
    for (int i = 0; i < 26; i++)
        if (letterCount[i] > 0) {
            char[] stars = new char[letterCount[i]];
            Arrays.fill(stars, '*');
            System.out.println((char)('a' + i) + ":" + new String(stars));
        }
}

Test

printLetterCounts("abaacc");
System.out.println();
printLetterCounts("This is a test of the letter counting logic");

Output

a:***
b:*
c:**

a:*
c:**
e:****
f:*
g:**
h:**
i:****
l:**
n:**
o:***
r:*
s:***
t:*******
u:*

answered Nov 13, 2015 at 22:13

Andreas

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1 Comment

Andreas Over a year ago

@Dana You have to import java.util.Arrays. If you're using an IDE, it should have told you that. If you're not using an IDE, then get one now, e.g. Eclipse, NetBeans, ...

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