import java.io.*;
import java.util.*;
 
public class FileDemo
{
    private String fileName; 
    private int[] letterCount = new int[26];
    
    public FileDemo (String fileName)
    {
        this.fileName = fileName;
        initialize();
    }
    
    private void initialize()
    {
        for(int i=0; i < letterCount.length; i++)
        {
            letterCount[i] = 0;
        }
    }
    
    public void processFile()
    {
        try
        {
            FileReader file = new FileReader(this.fileName);
            Scanner inFile = new Scanner(file);

            while (inFile.hasNext())
            {
                String line = inFile.nextLine();
                for(int i=0; i<line.length(); i++)
                {
                    char letter = line.charAt(i);
                    if(Character.isLetter(letter)) {
                        char upper = Character.toUpperCase(letter);
                        int charIndex = upper - 65;  //A=0, B=1, ... Z=25
                        this.letterCount[charIndex]++;
                    }
                }
            }
            
            inFile.close();
        }
        catch (FileNotFoundException e)
        {
            System.out.println("Cannot find that file");
        }
    }
    
    public void writeFile(String fileName)
    {
        try
        {
            PrintWriter file = new PrintWriter (new File (fileName));
            for(int i=0; i<this.letterCount.length; i++)
            {
                char tmp = (char) (i + 65);
                file.println(tmp + " = " + letterCount[i]);
            }
            file.close();
        }
        catch (FileNotFoundException exception)
        {
            System.out.println("Error - something went wrong in writeFile method");
        }
        
    }
}