Array/Element Question

[Polymer]

Trying to understand the mechanics of some code in this Array exercise.

What is the plain english translation of line 6?

"Create a String called 'current', and make it equal to the 'count' element of the String array 'phrase' "?

What about line 7?

"Create a char array called 'letters' and make it's value equal to the String 'current'...."

Thanks in advance!

class Wheel {
    public static void main(String[] args) {
        String phrase[] = {"Robot", "Alamo", "Cigarette", "Sugar Cane"};
        int[] letterCount = new int[26];
        for (int count = 0; count < phrase.length; count++) { 
            String current = phrase[count]; 
            char[] letters = current.toCharArray();
            for (int count2 = 0; count2 <letters.length; count2++) {
                char lett = letters[count2];
                if ( (lett >= 'A') & (lett <='Z')) {
                    letterCount[lett - 'A']++;
                }
                }
            }
            for (char count = 'A'; count <= 'Z'; count++) {
                System.out.print(count + ": " +
                    letterCount[count - 'A'] +
                    " ");
            }
            System.out.println();
    }
}

[Norm]

It looks like you have answered your own questions.
Or do you have further questions?

[Polymer]

It looks like you have answered your own questions.
Or do you have further questions?

Well, I am confused about whats going on after the '=' on line 6 and line 7.

[DarrylBurke]

Arrays (The Java™ Tutorials > Learning the Java Language > Language Basics)
String (Java Platform SE 6))

db

[Polymer]

Hey Darryl, thanks for the links - these cleared up a lot of other questions I had.

Unless I overlooked I didnt see anything directly relevant to line 6 however.

I certainly appreciate the senior members "teaching us to fish" vs just "feeding us", but after reading through all the supplied material I still dont understand the plain english that is occurring on line 6 after '=', which is 'phrase[count];' .

I understand we are doing something with the String array 'phrase' and the int 'count' that we defined in the 'for' statement above it, but I do not understand their relationship in this statement.

I'm sorry if it is a basic question, I've never programmed before and this is like my 3rd day into teaching myself Java. Can anyone explain this line to me like you might a child?

Thanks again in advance!

[JosAH]

Arrays are like a block of houses; every house has a unique number, starting at zero, so 0, 1, 2, ... etc. If the street is named 'phrase' then, say, 'phrase[2]' is the house with number 2. If the number is 'count' then 'phrase[count]' is the house with number 'count'. The value 'count' is called the index and of course 'phrase' isn't a row of houses but it is a row of Strings, so 'phrase[count]' is the 'count-th' String in the row (array).

kind regards,

Jos

[Polymer]

Thanks JosAH. I understand that st/house idea, at least conceptually.

Look, line 5 says to me:

for (int count = 0; count < phrase.length; count++) {

"in a for loop, create an int called 'count' and give it the value of zero; so long as count is < the number of variables stored in the phrase array (4); add 1 to 'count' "

Can someone transliterate lines 6 & 7 in this fashion?

[Norm]

variables represent computer memory addresses. An array uses memory in a range of memory addresses.
The address of the first element is at relative location 0. Say each element in phrase is 4 bytes long. Then address of the next element in the array is the beginning address + 4. The next one after that at +8 etc to the end of the array.
So the address of the element phase[count] is the address of phase + count *the length of an element.

[Polymer]

phrase + count*length of the element?

phrase.length= 4, but phrase is itself is a String. I can't add or multiple an int with a String.

Is anyone capable of dumbing this down a little? Just looking for a plain and simple plain english explanation of line 6 and 7. Narrate it for me.

6: "Create a String called 'current' and make it equal to (whatever is going on east of the '='.";
7: "Create a character array called 'letters' and make it equal to (whatever is going on east of the '='.;

Thank you for your help!

[Norm]

Sorry, there isn't a 'more dumb' way of explaining then has been used.
This is the best of the explanations, the one you gave:

Create a String called 'current', and make it equal to the 'count' element of the String array 'phrase'

What about this way: consider that an array is a row of mailboxes. If I ask you to look in the 4th mailbox for a String how would you find the one I'm refering to?
What if instead of asking the for 4th mailbox, I gave you a piece of paper with the number 4 written on it and asked you to go to the mailbox referred to by the number on the piece of paper. Could you find it?

[Polymer]

Yes, I think I could - thats a good analogy Norm.

I'm glad I was on the right track initially. Recall when I originally proposed "Create a String called 'current', and make it equal to the 'count' element of the String array 'phrase'?" it was in the form of a question.

I guess where I am still confused here is:

5: for (int count = 0; count < phrase.length; count++) {
6: String current = phrase[count];

Why do I need to reference the phrase array at all on line 6? To get the numerical value bring tested and modified by the for loop in line 5, why wouldn't I just say:

6: String current = count;
?

[Norm]

Going back to my example, count is the number on the piece of paper, NOT the contents of the mailbox.

[paul pasciak]

One of the qualities of the String variable "current"
is that it is not permanent. It is a temporary
workspace, along with the "letters" character array.
Beyond the scope of the line 5 for-loop, they cease
to exist.

(Notice they don't show up beyond line 14, where the
line 5 for-loop ends.)

1   class Wheel {
2       public static void main(String[] args) {
3           String phrase[] = {"Robot", "Alamo", "Cigarette", "Sugar Cane"};
4           int[] letterCount = new int[26];
5           for (int count = 0; count < phrase.length; count++) { 
6               String current = phrase[count]; 
7               char[] letters = current.toCharArray();
8               for (int count2 = 0; count2 <letters.length; count2++) {
9                   char lett = letters[count2];
10                  if ( (lett >= 'A') & (lett <='Z')) {
11                      letterCount[lett - 'A']++;
12                  }
13              }
14          }          
15          for (char count = 'A'; count <= 'Z'; count++) {
16              System.out.print(count + ": " +
17                  letterCount[count - 'A'] +
18                  " ");
19          }
20          System.out.println();
21      }
22  }

In each visit within the for-loop they perform the
same ol' same ol'..

1st visit:
current gets "Robot"
letters[] gets {R, o, b, o, t}

1st interation:
current gets "Alamo"
letters[] gets {A, l, a, m, o}

2nd interation:
current gets "Cigarette"
letters[] gets {C,i,g,a,r,e,t,t,e}

3rd interation:
current gets "Sugar Cane"
letters[] gets {S,u,g,a,r, ,C,a,n,e}


Work at lines 6 and 7 ends after the third
iteration because the for-loop on line 5
was programmed to run for the length of the
phrase[] String array (it has 4 Strings in it).