not correct num histgram - histogram

Question

Im trying to make a toString method that prints out a histogram that shows how often each character of the alphabet is used in a string. The most frequent character has to be 60 #s long, with the rest of the characters then scaled to match.
My issue is with making the equation that scales the rest of the letters to the correct length for the histogram. My current equation is (myArray[i]/max) * 60, but im getting really weird results.
If I put in "hello world" to be analyzed, L would be the most common occuring letter, seen 3 times. So L should have 60 #s for the histogram, h should have 20, o should have 40 etc. Instead im getting results like d : 10
e : 10
h : 10
l : 360
o : 20
r : 10
w : 10
Sorry for how sloppy this is right now, im just trying to figure out whats going on
public class LetterCounter
private static int[] alphabetArray;
private static String input;
/**
* Constructor for objects of class LetterCounter
*/
public LetterCounter()
{
alphabetArray = new int[26];
}
public void countLetters(String input) {
this.input = input;
this.input.toLowerCase();
//String s= input;
//s.toLowerCase();
for ( int i = 0; i < input.length(); i++ ) {
char ch= input.charAt(i);
if (ch >= 97 && ch <= 122){
alphabetArray[ch-'a']++;
}
}
}
public void getTotalCount() {
for (int i = 0; i < alphabetArray.length; i++) {
if(alphabetArray[i]>=0){
char ch = (char) (i+97);
System.out.println(ch +" : "+alphabetArray[i]);
}
}
}
public void reset() {
for (int i =0; i<alphabetArray.length; i++) {
if(alphabetArray[i]>=0){
alphabetArray[i]=0;
char ch = (char) (i+97);
System.out.println(ch +" : "+alphabetArray[i]);
}
}
}
public String toString() {
String s = "";
int max = alphabetArray[0];
int markCounter = 0;
for(int i =0; i<alphabetArray.length; i++) {
//finds the largest number of occurences for any letter in the string
if(alphabetArray[i] > max) {
max = alphabetArray[i];
}
}
for(int i =0; i<alphabetArray.length; i++) {
//trying to scale the rest of the characters down here
if(alphabetArray[i] > 0) {
markCounter = (alphabetArray[i] / max) * 60;
char ch = (char) (i+97);
System.out.println(ch +" : "+alphabetArray[i] + markCounter);
}
}
for (int i = 0; i < alphabetArray.length; i++) {
//prints the whole alphabet, total number of occurences for all chars
if(alphabetArray[i]>=0){
char ch = (char) (i+97);
System.out.println(ch +" : "+alphabetArray[i]);
}
}
return s;
}
}

Answer 1

There are many many problems with your code, but lets go one by one.
First of all, your print statement is simply misleading. Change it to
System.out.println(ch +" : "+alphabetArray[i] + " " + markCounter);
and you will see
d : 1 0
e : 1 0
h : 1 0
l : 3 60
o : 2 0
r : 1 0
w : 1 0
As you can see: the counters are correct (1,1,1,3,2,1,1). But the your scaling doesn't work:
1 / 3 --> 0 ... and 0 * 3 ... is still 0
3 / 3 --> 1 and 1 * 3 ... is 60
but of course, when you dont print a space between 1 and 0 and 3 and 60.
Thus to get correct scaling, just change to:
markCounter = alphabetArray[i] * 60 / max;
Other things worth mentioning:
You are overriding toString(). Then you should put #Override in fron t of that method
toLowerCase() returns a new string in lower case; just calling it without pushing the result back into your string ... just throws away the "lower casing".
toString() shouldnt print to the console. The whole idea is that you put all the information into the string that you return. In other words: in the end you do some System.out.println(someLetterCounter.toString()
Your code is extremely low-level. You don't iterate arrays using for (int), you can do (int letter : alphabetArray) instead
You might want to read about Map. You see, if you would be using a Map<Character, Integer> where the map key would represent the different characters, and the map value represents a counter for each character ... well, you could throw out most of your code; and come up with a solution that would require a few lines of code only!
( and seriously: because of all these issues, debugging your code was really much harder than it needed to be )

Answer 2

countLetters seems has some issues. You can not convert String to lowercase by just calling
this.input.toLowerCase();
Because String is immutable in java. You have to assign it like:
this.input = input.toLowerCase();
Another problem is you are using input variable from parameter instead of this.input which has lower case string. You can do this way to make work countLetters method:
public void countLetters(String input) {
this.input = input.toLowerCase();
for ( int i = 0; i < this.input.length(); i++ ) {
char ch= this.input.charAt(i);
if (ch >= 97 && ch <= 122) {
alphabetArray[ch-'a']++;
}
}
}