Thread: Understanding String(s)

Hi,

I'm having a hard time understanding strings, how they can be compared, and how they can be used as charAt. I guess I'll present it as a problem. Let's say I am having a contest for my company and you have to enter four words on my site. So, the JOptionpane will prompt the customer/user to enter the four words. But, if there are more than four words it will loop to say they have entered too many.

What I don't understand is how to code for something past a certain amount with Strings since if I put something with < or > I always get an error message. I'm guessing I need to convert the String but then I'm confused about how to use charAt to indicate if they entered the correct code. I know how to use charAt on it's own but am confused how to have a loop that works without also messing up the charAt. Can someone please explain this to me? (If it would be more helpful I can create a code and paste it.)

Thanks for any advice.
Adam

Go through the String chapter in The Java Tutorial: Strings (The Java™ Tutorials > Learning the Java Language > Numbers and Strings). This chapter has sections on String manipulation and comparison. Consult also the String API documentation for the operations that you can perform with a String: String (Java Platform SE 7 ).

After that, give it a go with writing the code,. If you have trouble getting it to work, post your code here (wrapped in [code] tags) together with details of the problem and error messages.

Originally Posted by Adam Appleby

Hi,

I'm having a hard time understanding strings, how they can be compared, and how they can be used as charAt. I guess I'll present it as a problem. Let's say I am having a contest for my company and you have to enter four words on my site. So, the JOptionpane will prompt the customer/user to enter the four words. But, if there are more than four words it will loop to say they have entered too many.

What I don't understand is how to code for something past a certain amount with Strings since if I put something with < or > I always get an error message. I'm guessing I need to convert the String but then I'm confused about how to use charAt to indicate if they entered the correct code. I know how to use charAt on it's own but am confused how to have a loop that works without also messing up the charAt. Can someone please explain this to me? (If it would be more helpful I can create a code and paste it.)

Thanks for any advice.
Adam

It seems that you want to count the characters/words a String has, and you are trying to do it using the charAt function of String. The function's name of each object in java is a simple english and just by reading its name you'll get an idea on what it is doing, or what it can do. Just by reading the name of function chartAt, I think it is getting a character from specified index rather than counting how many characters/words does the String has.
And if you want to know how to count its characters/words you better go to the site that jashburn provided and read all the function of String object. I'm sure you'll get there want you want.

I've read the above and still don't understand. It sounds simple but I just don't get how to use a String where I can compare words since whatever I do I get an error saying there is a problem with the variable. This is my code:

import javax.swing.*;
import java.util.Scanner;

public class ThreeLetterAcronym {

public static void main(String[] arg){


String threeWord = JOptionPane.showInputDialog(null, "Hi!"
+ "Please enter your three words to be used for "
+ "your acronym");

Scanner input = new Scanner(threeWord);

String[] tokens = threeWord.split("");

if(tokens > 4)//error. Do not know how to indicate if the user put more than three words without using ">".

char a = input.next().charAt(0);
a = Character.toUpperCase(a);


char b = input.next().charAt(0);
b = Character.toUpperCase(b);


char c = input.next().charAt(0);
c = Character.toUpperCase(c);


input.close();
}

}

'tokens' is an array, not a number so you can't compare it as one, arrays do have a public field called length to indicate how many values are in it, so if(tokens.length > 4) would work.

So I can just use the length() to change them and complete the loop?

Please post your code between code tags, not quote tags.

From this line:

String[] tokens = threeWord.split("");

the variable tokens is intended to be AN ARRAY of String objects or literals. However, since the quotes in your call to the split() method are empty, I'm not sure what you'll get. Assuming the user will enter spaces between the words, add a space between the quotes.

Then, this line

if(tokens > 4)

can be changed to:

if( tokens.length > 4 ),

but I think you mean '> 3' rather than '> 4'. And then your if statement needs a body that makes sense.