How to fill an arraylist with nothing so i do not get index out of bounds exception

Question

My code give me an index out of bounds because the index = 0 and size = 0 how can i fix this? Basically what this code should do is find the frequency of the letters in the string and add them all up together in the arraylist. the array list is in alphabetical order so at 0 it would represent the frequency for the letter a...

import java.io.*;
import java.util.*;

public class Encoding {
   ArrayList<Integer> frequency;

public void frequency(String fileName) {
    frequency = new ArrayList<Integer>();
    try {
        Scanner scan = new Scanner(new File(fileName));
        while(scan.hasNextLine()){
            String line = scan.nextLine();
            Scanner token = new Scanner (line);
            while(token.hasNext()){
                String s = token.next();
                countLettersInString(s);
            }
        }
        System.out.println(frequency);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

public void countLettersInString(String s) {

    int count = 0;
    int position = 0;

    s = s.toLowerCase();
    for (char i = 'a'; i <= 'z'; i++) {
        count = 0;
        for (int j = 0; j < s.length(); j++) {
            char c = s.charAt(j);
            if (c == i)
                count++;
        }
        int oldCount = frequency.get(position);
        frequency.add(position, oldCount+count);
        position++;
    }
}

}

Don't fill it with nothing, just write better code. For example check if `position >= frequency.size()`, like you always should. — Tom, Apr 30 '17 at 22:14
Possible duplicate of [How to count frequency of characters in a string?](http://stackoverflow.com/questions/6712587/how-to-count-frequency-of-characters-in-a-string) — Tom, Apr 30 '17 at 22:14

score 0 · Accepted Answer · answered Apr 30 '17 at 22:20

0

What if you tried it by creating an arrayList of objects that represent each letter in the alphabet and each letter has a frequency that you can just add onto if the letter is in the given string.

answered Apr 30 '17 at 22:20

Abbey Nichols

16

How to fill an arraylist with nothing so i do not get index out of bounds exception

1 Answers1