Doubt about Vertical Histogram with a for loops

**georgio777** · 03-31-2010, 07:48 AM

Hi everyone,

I am writing a program which reads all the characters of a text file and determines how many times each letter of the English alphabet appears in the text file. Afterwards, the program should print a vertical histogram showing the 26 English letters frequencies. The name of the text file should be provided as a command line argument when you run the program.

Here is what I have done by now:

Java Code:

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

public class Lab10b
{
	public static void main(String[] args) throws IOException
	{
		Scanner fileScan;
		String line;
		char currentChar;
		int [] array = new int [26];
		int max = 0, currentValue;
		fileScan = new Scanner(new File(args[0]));
		while (fileScan.hasNext())
		{
			line = fileScan.nextLine();
			line = line.toLowerCase();
			for(int counter=0; counter < line.length(); counter = counter +1)
			{
				currentChar = line.charAt(counter);
			
				if (currentChar == 'a')
					array[0]++;
				else if (currentChar == 'b')
					array[1]++;
				else if (currentChar == 'c')
					array[2]++;
				else if (currentChar == 'd')
					array[3]++;
				else if (currentChar == 'e')
					array[4]++;
				else if (currentChar == 'f')
					array[5]++;
				else if (currentChar == 'g')
					array[6]++;
				else if (currentChar == 'h')
					array[7]++;
				else if (currentChar == 'i')
					array[8]++;
				else if (currentChar == 'j')
					array[9]++;
				else if (currentChar == 'k')
					array[10]++;
				else if (currentChar == 'l')
					array[11]++;
				else if (currentChar == 'm')
					array[12]++;
				else if (currentChar == 'n')
					array[13]++;
				else if (currentChar == 'o')
					array[14]++;
				else if (currentChar == 'p')
					array[15]++;
				else if (currentChar == 'q')
					array[16]++;
				else if (currentChar == 'r')
					array[17]++;
				else if (currentChar == 's')
					array[18]++;
				else if (currentChar == 't')
					array[19]++;
				else if (currentChar == 'u')
					array[20]++;
				else if (currentChar == 'v')
					array[21]++;
				else if (currentChar == 'w')
					array[22]++;
				else if (currentChar == 'x')
					array[23]++;
				else if (currentChar == 'y')
					array[24]++;
				else if (currentChar == 'z')
					array[25]++;
			}
		}
		for(int i = 0; i <= 25; i++)
		{
			if (array[i] > max)
				max = array[i];	
		}
		currentValue = max;
		for(int i = 0;  i <= max; i++)
		{
			for(int j = 0; j <= 25; j++)
			{
				if(array[j] <= currentValue)
					System.out.print(" ");
				else
					System.out.print("*");
			}
			System.out.println();
			currentValue--;
		}
		System.out.println("abcdefghijklmnopqrstuvwxyz");			
	}
}

Here is an example of a file to read:

Friends are God's way of taking care of us.
Friendship doubles your joys, and divides your sorrows.
A friend is someone who walks in when the whole world has walked out.

Here is the Output:

Java Code:

                          [COLOR="Red"][B]<----This BLANK Line[/B][/COLOR]
              *           
              *           
    *         *   *       
    *         *   *       
    *         *   *       
   **         *  **       
*  **   *     *  **       
*  **   *    **  **   *   
*  **   *    **  **   *   
*  **  **    **  **   *   
*  *** **  * **  ** * *   
*  *** **  * **  ** * * * 
*  *** ** ** **  **** * * 
*  ****** ** **  **** * * 
**************** ****** * 
abcdefghijklmnopqrstuvwxyz

My issue is that I am getting a blank line in the first line of the output. I can't find the problem causing it, I guess is in the for loop. Hope you can help me out.

Thanks!

**gcalvin** · 03-31-2010, 08:55 AM

Originally Posted by georgio777

Java Code:

				if(array[j] <= currentValue)
					System.out.print(" ");
				else
					System.out.print("*");

Look carefully at that first line.

Also, you can do math on char values, and you can leverage that to get rid of that whole block of if..else if. (hint: array[currentChar - 'a']++)

-Gary-

**georgio777** · 03-31-2010, 09:08 AM

What's the deal with

Java Code:

if(array[j] <= currentValue)

I am doing something wrong?

**gcalvin** · 03-31-2010, 09:13 AM

You have more of letter o than anything else in your sample text -- 15 of them. The o element is array[14]. So what will this code print when j = 14 and currentValue = 15? What do you want it to print?

Java Code:

				if(array[j] <= currentValue)
					System.out.print(" ");
				else
					System.out.print("*");

-Gary-

**georgio777** · 03-31-2010, 09:22 AM

Oh my god, now I get it, how dummy I am!

Thanks for the help!

**gcalvin** · 03-31-2010, 09:25 AM

Please consider posting your final code, and marking the thread SOLVED.

-Gary-

**georgio777** · 03-31-2010, 09:37 AM

Here is the final code:
In red are the changes from the original.

Java Code:

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

public class Lab10b
{
	public static void main(String[] args) throws IOException
	{
		Scanner fileScan;
		String line;
		char currentChar;
		int [] array = new int [26];
		int max = 0, currentValue;
		fileScan = new Scanner(new File(args[0]));
		while (fileScan.hasNext())
		{
			line = fileScan.nextLine();
			line = line.toLowerCase();
			for(int counter=0; counter < line.length(); counter = counter +1)
			{
				currentChar = line.charAt(counter);
			
				if (currentChar == 'a')
					array[0]++;
				else if (currentChar == 'b')
					array[1]++;
				else if (currentChar == 'c')
					array[2]++;
				else if (currentChar == 'd')
					array[3]++;
				else if (currentChar == 'e')
					array[4]++;
				else if (currentChar == 'f')
					array[5]++;
				else if (currentChar == 'g')
					array[6]++;
				else if (currentChar == 'h')
					array[7]++;
				else if (currentChar == 'i')
					array[8]++;
				else if (currentChar == 'j')
					array[9]++;
				else if (currentChar == 'k')
					array[10]++;
				else if (currentChar == 'l')
					array[11]++;
				else if (currentChar == 'm')
					array[12]++;
				else if (currentChar == 'n')
					array[13]++;
				else if (currentChar == 'o')
					array[14]++;
				else if (currentChar == 'p')
					array[15]++;
				else if (currentChar == 'q')
					array[16]++;
				else if (currentChar == 'r')
					array[17]++;
				else if (currentChar == 's')
					array[18]++;
				else if (currentChar == 't')
					array[19]++;
				else if (currentChar == 'u')
					array[20]++;
				else if (currentChar == 'v')
					array[21]++;
				else if (currentChar == 'w')
					array[22]++;
				else if (currentChar == 'x')
					array[23]++;
				else if (currentChar == 'y')
					array[24]++;
				else if (currentChar == 'z')
					array[25]++;
			}
		}
		for(int i = 0; i <= 25; i++)
		{
			if (array[i] > max)
				max = array[i];	
		}
		[COLOR="red"][B]max--;[/B][/COLOR]
		currentValue = max;
		for(int i = 0;  i <= max; i++)
		{
			for(int j = 0; j <= 25; j++)
			{
				if(array[j] <= currentValue)
					System.out.print(" ");
				else
					System.out.print("*");
			}
			System.out.println();
			currentValue--;
		}
		System.out.println("abcdefghijklmnopqrstuvwxyz");			
	}
}

**gcalvin** · 03-31-2010, 09:40 AM

Yikes! No, that's not it. I'm glad you posted it. Take a look again at the line I called your attention to. Don't be confused by the array index and the value stored at that index.

-Gary-

**gcalvin** · 03-31-2010, 09:43 AM

Also, did you read what I wrote about char arithmetic?

-Gary-

**georgio777** · 03-31-2010, 09:53 AM

Originally Posted by gcalvin

Yikes! No, that's not it. I'm glad you posted it. Take a look again at the line I called your attention to. Don't be confused by the array index and the value stored at that index.

-Gary-

You are suggesting to change the line to

Java Code:

if(array[j] < currentValue)

**gcalvin** · 03-31-2010, 09:56 AM

Yes. Can you tell me why?

Also, it's a completely separate issue, but do you understand what I meant about char arithmetic?

-Gary-

**georgio777** · 03-31-2010, 09:56 AM

Originally Posted by gcalvin

Also, did you read what I wrote about char arithmetic?

-Gary-

Yeah, I read that, but the issue is that I am taking Java classes and the teacher is grading based on what we know by now. Anyway I am going to take it into consideration.

**georgio777** · 03-31-2010, 10:03 AM

Originally Posted by gcalvin

Yes. Can you tell me why?

Also, it's a completely separate issue, but do you understand what I meant about char arithmetic?

-Gary-

Well if I change the line

Java Code:

if(array[j] < currentValue)

When j = 14 and currentValue = 15 its going to print the asterisk instead of the space.

I don't really get what you meant with char arithmetic, I related to what you said about getting rid of the if, if else statements.

**georgio777** · 03-31-2010, 10:07 AM

Also, with the new changes I realized that the output is still wrong:

Java Code:

              *           
              *           
    *         *   *       
    *         *   *       
    *         *   *       
   **         *  **       
*  **   *     *  **       
*  **   *    **  **   *   
*  **   *    **  **   *   
*  **  **    **  **   *   
*  *** **  * **  ** * *   
*  *** **  * **  ** * * * 
*  *** ** ** **  **** * * 
*  ****** ** **  **** * * 
**************** ****** * 
[B][COLOR="Red"]**************************[/COLOR][/B]
abcdefghijklmnopqrstuvwxyz

A new line appeared...

The solution I gave before works, the blank line has disappeared and the output is correct.

**gcalvin** · 03-31-2010, 05:30 PM

Originally Posted by georgio777

The solution I gave before works, the blank line has disappeared and the output is correct.

It "works" because you've gotten yourself hopelessly confused, and your errors happen to cancel each other out. You're computing max correctly, then decrementing it for no reason. Then you're counting up in a loop that should be counting down, which forces you to use a superfluous currentValue variable, and you are doing one too many iterations in that loop. Finally, you are using a wrong comparison which, combined with the extra loop iteration reverses the off-by-one error you introduced by decrementing max.

I'm going to hate myself for doing this, but here is the correct code.

Java Code:

		for(int i = max;  i > 0; i--)
		{
			for(int j = 0; j < 26; j++)
			{
				if(array[j] < i)
					System.out.print(" ");
				else
					System.out.print("*");
			}
			System.out.println();
		}
		System.out.println("abcdefghijklmnopqrstuvwxyz");