I need some help with Java programming...?

Question

I have a program that I don't really understand.. Will someone help me?
This is what I have so far:

import java.util.Scanner;

public class Counts
{
public static void main (String[] args)
{
String phrase; // a string of characters
int countBlank; // the number of blanks in the phrase
int length; // the length of the phrase
char ch; // an individual character in the string
int count;

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 char by char
// and count the blank spaces


// Print the results
System.out.println ();
System.out.println ("Number of blank spaces: " + countBlank);
System.out.println ();
}
}

These are the directions:

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.

Please help, I really don't understand...

Answer 1

Here is the "for" loop.



for (int i = 0; i < length; i++)

if (phrase.charAt(i) == ' ')

countBlank++;





For question #3 change the "for" statement above to a switch statement as following:



for (int i = 0; i < length; i++){

ch = phrase.charAt(i);

switch(ch){

case 'A':

countA++;

break;

case 'a':

countA++;

break;

case ' ':

countBlank++;

break;

case 'E':

countE++;

break;

case 'e':

countE++;

break;

case 'S':

countS++;

break;

case 's':

countS++;

break;

case 'T':

countT++;

break;

case 't':

countT++;

break;

}

}



You also need to declare a few new variables at the top as following:

int countA = 0;

int countE = 0;

int countS = 0;

int countT = 0;



One more thing you have to do for question #3 is print out how many of each number there are. do this as following:

System.out.println ("Number of A's: " + countA);

System.out.println ("Number of E's: " + countE);

System.out.println ("Number of S's: " + countS);

System.out.println ("Number of T's: " + countT);



Question #5 is simple, all you have to do is surround the whole thing in a "while" loop and exit the loop only after the user types in "quit". Here is how the finished program should look like.



import java.util.Scanner;







public class Test{



public static void main(String[] args){

String phrase = ""; // a string of characters

int countBlank; // the number of blanks in the phrase

int length; // the length of the phrase

char ch; // an individual character in the string

int count;

int countA = 0;

int countE = 0;

int countS = 0;

int countT = 0;



Scanner scan = new Scanner(System.in);



// Print a program header

System.out.println ();

System.out.println ("Character Counter");

System.out.println ();



while(!phrase.equals("quit")){

// Read in a string and find its length

System.out.print ("Enter a sentence or phrase or enter quit: ");

phrase = scan.nextLine();

if (phrase.equals("quit"))

break;

length = phrase.length();



// Initialize counts

countBlank = 0;



for (int i = 0; i < length; i++){

ch = phrase.charAt(i);

switch(ch){

case 'A':

countA++;

break;

case 'a':

countA++;

break;

case ' ':

countBlank++;

break;

case 'E':

countE++;

break;

case 'e':

countE++;

break;

case 'S':

countS++;

break;

case 's':

countS++;

break;

case 'T':

countT++;

break;

case 't':

countT++;

break;

}

}





// Print the results

System.out.println ();

System.out.println ("Number of blank spaces: " + countBlank);

System.out.println ("Number of A's: " + countA);

System.out.println ("Number of E's: " + countE);

System.out.println ("Number of S's: " + countS);

System.out.println ("Number of T's: " + countT);

System.out.println ();

}

}

}

Answer 2

From what I read so far, it looks like the user is going to input a string i.e. "I Like Walnuts"

And your program has to count how many spaces are in that string which is 2 in this example.



phrase = scan.nextLine();



This phrase variable represents the string that the user put in.

So, now you need a for loop to iterate through each of characters within the string.

As you iterate through each character, you will perform a check to see whether or not that character is a "space". If it is a space, then increment the countBlank by 1.



for (int i = 0; i < length -1; i++) {

// If current character is a space then increment countBlank by 1.

}

Answer 3

Why roll your own when there is in all probability a calendar widget that you may reuse? By the way, the Java API itself supplies many priceless courses and interfaces: Date, Calendar, GregorianCalendar, DateFormat, and SimpleDateFormat.