Counting Characters The file Count.java contains the skeleton of a program to re
ID: 3795791 • Letter: C
Question
Counting Characters
The file Count.java contains the skeleton of a program to read in a string (a sentence or phrase) and count the number of
blank spaces in the string. The program currently has the declarations and initializations and prints the results. All it needs is
a loop to go through the string character by character and count (update the countBlank variable) the characters that are the
blank space. Since we know how many characters there are (the length of the string) we use a count controlled loop—for
loops are especially well-suited for this.
1. Add the for loop to the program. Inside the for loop you need to access each individual character—the charAt method of
the String class lets you do that. The assignment statement
ch = phrase.charAt(i);
assigns the variable ch (type char) the character that is in index i of the String phrase. In your for loop you can use an
assignment similar to this (replace i with your loop control variable if you use something other than i). NOTE: You could
also directly use phrase.charAt(i) in your if (without assigning it to a variable).
2. Test your program on several phrases to make sure it is correct.
3. Now modify the program so that it will count several different characters, not just blank spaces. To keep things relatively
simple we’ll count the a’s, e’s, s’s, and t’s (both upper and lower case) in the string. You need to declare and initialize
four additional counting variables (e.g. countA and so on). Your current if could be modified to cascade but another solution
is to use a switch statement. Replace the current if with a switch that accounts for the 9 cases we want to count (upper
and lower case a, e, s, t, and blank spaces). The cases will be based on the value of the ch variable. The switch starts as
follows—complete it.
switch (ch)
{
case 'a':
case 'A': countA++;
break;
case ....
}
Note that this switch uses the “fall through” feature of switch statements. If ch is an ‘a’ the first case matches and the
switch continues execution until it encounters the break hence the countA variable would be incremented.
4. Add statements to print out all of the counts.
5. It would be nice to have the program let the user keep entering phrases rather than having to restart it every time. To do
this we need another loop surrounding the current code. That is, the current loop will be nested inside the new loop. Add
an outer while loop that will continue to execute as long as the user does NOT enter the phrase quit. Modify the prompt
to tell the user to enter a phrase or quit to quit. Note that all of the initializations for the counts should be inside the while
loop (that is we want the counts to start over for each new phrase entered by the user). All you need to do is add the
while statement (and think about placement of your reads so the loop works correctly). Be sure to go through the
program and properly indent after adding code—with nested loops the inner loop should be indented.
Chapter 6: More Conditionals and Loops 77
// ************************************************************
// Count.java
//
// This program reads in strings (phrases) and counts the
// number of blank characters and certain other letters
// in the phrase.
// ************************************************************
import java.util.Scanner;
public class Count
{
public static void main (String[] args)
{
String phrase; // a string of characters
int countBlank; // the number of blanks (spaces) in the phrase
int length; // the length of the phrase
char ch; // an individual character in the string
Scanner scan = new Scanner(System.in);
// Print a program header
System.out.println ();
System.out.println ("Character Counter");
System.out.println ();
// Read in a string and find its length
System.out.print ("Enter a sentence or phrase: ");
phrase = scan.nextLine();
length = phrase.length();
// Initialize counts
countBlank = 0;
// a for loop to go through the string character by character
// and count the blank spaces
// Print the results
System.out.println ();
System.out.println ("Number of blank spaces: " + countBlank);
System.out.println ();
Explanation / Answer
Hi, Please find my implementation.Please let me know in case of any issue.
//************************************************************
//Count.java
//
//This program reads in strings (phrases) and counts the
//number of blank characters and certain other letters
//in the phrase.
//************************************************************
import java.util.Scanner;
public class Count
{
public static void main (String[] args)
{
String phrase; // a string of characters
int countBlank; // the number of blanks (spaces) in the phrase
int length; // the length of the phrase
char ch; // an individual character in the string
Scanner scan = new Scanner(System.in);
//Print a program header
System.out.println ();
System.out.println ("Character Counter");
System.out.println ();
//Read in a string and find its length
System.out.print ("Enter a sentence or phrase: ");
phrase = scan.nextLine();
length = phrase.length();
//Initialize counts
countBlank = 0;
//a for loop to go through the string character by character
//and count the blank spaces
for(int i=0; i<length; i++){
if(phrase.charAt(i) == ' ')
countBlank++;
}
//Print the results
System.out.println ();
System.out.println ("Number of blank spaces: " + countBlank);
System.out.println ();
}
}
/*
Sample run:
Character Counter
Enter a sentence or phrase: This is the sample phrase
Number of blank spaces: 4
*/