code: import java.io.BufferedReader;
  import java.io.FileReader;
  import java.io.IOException;
  import java.util.Arrays;
  
  public class LetterFreq {
  	public static int[] countLetters(String filename) throws IOException{
  		int[] freqs = new int[26];
  		BufferedReader in = new BufferedReader(new FileReader(filename));
  		String line;
  		while((line = in.readLine()) != null){
  			line = line.toUpperCase();
  			for(char ch:line.toCharArray()){
  				if(Character.isLetter(ch)){
  					freqs[ch - 'A']++;
  				}
  			}
  		}
  		in.close();
  		return freqs;
  	}
  	
  	public static void main(String[] args) throws IOException{
  		System.out.println(Arrays.toString(countLetters("filename.txt")));
  	}
  }
  