stringbuffer/stringbuilder help

[jcarosella10]

I need to turn an array of strings into a string to be returned. The only problem is that it needs to go like this:

string[0] + ", " + string[1] +.......... + " and " + string[last]

the loops I'm writing aren't working correctly and I'm a little rusty with StringBuffer. Could someone help me write a short method to do this?

Thanks

[Fubarable]

Sure -- but you first! :)

Seriously though, don't you think it would be much better for you to show us your attempt so we can see what you might be doing wrong and so you can exercise those "rusty" muscles?

[jcarosella10]

I guess i worded that badly...
I can get a stringbuffer to build a string out of a string array, but i'm not sure how to change it so that the last connecting part will be " and " instead of ", ". I'll put up what i have so far.

[Fubarable]

I guess i worded that badly...
I can get a stringbuffer to build a string out of a string array, but i'm not sure how to change it so that the last connecting part will be " and " instead of ", ". I'll put up what i have so far.

Hint: You know the length of the array -- try to use that information to your advantage.

[jcarosella10]

oh like a recursion? i switched to stringbuilder since they're a little more user friendly in this situation

[jcarosella10]

 public Textbook(int pages, String name, int Numberauthors, boolean hard, String pc, String subject)
    {
        super(pages);
        numpages = pages;
        title = name;
        numauthors = Numberauthors;
        String[] authors = new String[numauthors];
        allauthors = makeString(authors[numauthors], numauthors);
        hardCover = hard;
        open = false;
        pubComp = pc;
        field = subject;
    }

I'm getting an error on line eight above. I'll show you the method being called and the error message....

private String makeString(String[] authorlist, int num)
    {
       StringBuilder builder = new StringBuilder(authorlist[0]);
       for(int counter = 0; counter < num; counter++)
       {
           if((counter + 1) != num)
                builder.append(", " + authorlist[counter]);
           else
                builder.append(" and " + authorlist[counter]);
       }
       return builder.toString();
    }

The error messages says:
"method makeString in class Textbook cannot be applied to given types;
required: java.lang.String[], int found: java.lang.String, int reason: actual argument java.lang.String cannot be converted to java.lang.String[]"
I'm getting that error even though authors is an array. Is this error my fault?

[Fubarable]

oh like a recursion? i switched to stringbuilder since they're a little more user friendly in this situation

No, you wouldn't use recursion at all here. You'd use a for loop, looping through the array loop, and the behavior of the code in the loop will be different depending on what the loop index is...

[jcarosella10]

think i got the loop down, its just that error saying that my string array is not a string array.....

[Fubarable]

makeString accepts a String array and an int. You are passing only a String into it, not an array of String. But a bigger problem I see is that I don't see any authors array being passed in as a parameter to your Textbook class's constructor.

[jcarosella10]

It compiles now, thanks for catching that. I got lost in all the inherited nonsense

public class Textbook extends Book
{
    private int numpages;
    private String title;
    private int numauthors;
    private String allauthors;
    private String[] authors;
    private boolean hardCover;
    private boolean open;
    private String pubComp;
    private String field;
    public Textbook(int pages, String name, String[] xauthors, int Numberauthors, boolean hard, String pc, String subject)
    {
        super(pages);
        numpages = pages;
        title = name;
        numauthors = Numberauthors;
        authors = xauthors;
        allauthors = makeString(authors, numauthors);
        hardCover = hard;
        open = false;
        pubComp = pc;
        field = subject;
    }
    public int numPages()
    {
        return numpages;
    }
    public String bookTitle()
    {
        return title;
    }
    public String authorName()
    {
        return allauthors;
    }
    public boolean isHardCover()
    {
        return hardCover;
    }
    public boolean isOpen()
    {
        return open;
    }
    public void open()
    {
        open = true;
    }
    public void close()
    {
        open = false;
    }
    public String publishingCompany()
    {
        return pubComp;
    }
    private String makeString(String[] authorlist, int num)
    {
       StringBuilder builder = new StringBuilder(authorlist[0]);
       for(int counter = 0; counter < num; counter++)
       {
           if((counter + 1) != num)
                builder.append(", " + authorlist[counter]);
           else
                builder.append(" and " + authorlist[counter]);
       }
       return builder.toString();
    }
}