Question
I need help on how to solve this programming prompt. File CountLetters.java contains a program that reads a word from the user and prints the
I need help on how to solve this programming prompt.
File CountLetters.java contains a program that reads a word from the user and prints the number of occurrences of each letter in the word. Save it to your directory and study it, then compile and run it to see how it works. In reading the code, note that the word is converted to all upper case first, then each letter is translated to a number in the range 0..25 (by subtracting 'A') for use as an index. No test is done to ensure that the characters are in fact letters.
- Run CountLetters and enter a phrase, that is, more than one word with spaces or other punctuation in between. It should throw an ArrayIndexOutOfBoundsException, because a non-letter will generate an index that is not between 0 and 25. It might be desirable to allow non-letter characters, but not count them. Of course, you could explicitly test the value of the character to see if it is between 'A' and 'Z'. However, an alternative is to go ahead and use the translated character as an index, and catch an ArrayIndexOutOfBoundsException if it occurs. Since you want don't want to do anything when a nonletter occurs, the handler will be empty. Modify this method to do this as follows:
- Put a try-catch in the body of the first for loop. In other words, the counts statement should be in the try block that is in the first for loop.
- Add a catch that catches the exception, but don't do anything with it.
Compile and run your program.
// ****************************************************************
// CountLetters.java
//
// Reads a words from the standard input and prints the number of
// occurrences of each letter in that word.
//
// ****************************************************************
import java.util.Scanner;
public class CountLetters
{
public static void main(String[] args)
{
int[] counts = new int[26];
Scanner scan = new Scanner(System.in);
//get word from user
System.out.print("Enter a single word (letters only, please): ");
String word = scan.nextLine();
//convert to all upper case
word = word.toUpperCase();
//count frequency of each letter in string
for (int i=0; i < word.length(); i++)
counts[word.charAt(i)-'A']++;
//print frequencies
System.out.println();
for (int i=0; i < counts.length; i++)
if (counts [i] != 0)
System.out.println((char)(i +'A') + ": " + counts[i]);
}
}
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