array of arrays question

[jim]

Hi,

I'm trying to load values into an array of arrays. I have a 5x10 array like
so:
String[][] words = new String[5][10];

and i have a method that returns an array of 10 words. so I want to load
the results of the method into the multidimensional array at [0][x].

words[0][] = returnWords();

This doesm't work ("Array index required"), but this does:

String[] moreWords = new String[10];
moreWords[] = returnWords();

any help appreciated!
jim

[Paul Clapham]

And then

for (int i=0; i<10; i++)
words[0][i] = moreWords[i];

PC2

"jim" <the_nach@hotmail.com> wrote in message
news:3bb78222$1@news.devx.com...
>
> Hi,
>
> I'm trying to load values into an array of arrays. I have a 5x10 array
like
> so:
> String[][] words = new String[5][10];
>
> and i have a method that returns an array of 10 words. so I want to load
> the results of the method into the multidimensional array at [0][x].
>
> words[0][] = returnWords();
>
> This doesm't work ("Array index required"), but this does:
>
> String[] moreWords = new String[10];
> moreWords[] = returnWords();
>
> any help appreciated!
> jim

[jim]

Thanks. That's what I ended up using.


"Paul Clapham" <pclapham@core-mark.com> wrote:
>And then
>
>for (int i=0; i<10; i++)
> words[0][i] = moreWords[i];
>
>PC2
>
>"jim" <the_nach@hotmail.com> wrote in message
>news:3bb78222$1@news.devx.com...
>>
>> Hi,
>>
>> I'm trying to load values into an array of arrays. I have a 5x10 array
>like
>> so:
>> String[][] words = new String[5][10];
>>
>> and i have a method that returns an array of 10 words. so I want to load
>> the results of the method into the multidimensional array at [0][x].
>>
>> words[0][] = returnWords();
>>
>> This doesm't work ("Array index required"), but this does:
>>
>> String[] moreWords = new String[10];
>> moreWords[] = returnWords();
>>
>> any help appreciated!
>> jim
>
>

[Roy Lachapelle]

Jim, You claimed that your were able to do this:
...
String[] moreWords = new String[10];
moreWords[] = returnWords();
...
I added a returnWords() method like this:

public String[] returnWords()
{
String[] s = {"1","2","3","4","5","6","7","8","9","10"};
return s;
}

and received the following errors during the compile using JDK 1.3.1:

Test.java:15: not a statement
moreWords[] = returnWords();
^
Test.java:15: ';' expected
moreWords[] = returnWords();
^

Even if you are using an older JDK that allows this, you may be replacing
the reference for your string array, making the 'new String[]'
initialization useless. In any case, it's dangerous code, and might be
confusing to maintain.

You might be better off just writing a routine that gets the size
of the return array, loops through the entries and assigns them
(keep that method in a utility class, because you'll use it a lot).
Alternatively, take a look at the System.arraycopy(...) method (may not
be exactly what you want, but may make less work of a utility method).

Last, remember that each 'sub' array can be a different length.
Take a look at this code:
...
String[][] moreWords = new String[5][]; // notice no secondary length
moreWords[0] = returnWords(3);
moreWords[1] = returnWords(10);
System.out.println("moreWords[0][1] = " + moreWords[0][1]);
System.out.println("moreWords[1][9] = " + moreWords[1][9]);
System.out.println("moreWords.length = " + moreWords.length);
System.out.println("moreWords[0].length = " + moreWords[0].length);
System.out.println("moreWords[1].length = " + moreWords[1].length);
...

public String[] returnWords(int numWords)
{
if (numWords < 0)
{
numWords = 0;
}
String[] s = new String[numWords];
for (int i = 0; i < numWords; i++)
{
s[i] = "string " + (i+1) + " of " + numWords;
}
return s;
}

This code produced:

moreWords[0][1] = string 2 of 3
moreWords[1][9] = string 10 of 10
moreWords.length = 5
moreWords[0].length = 3
moreWords[1].length = 10

Attempting to access 'moreWords[0][7]' would result in a
java.lang.ArrayIndexOutOfBoundsException to be thrown.

Ok, I know it might not be exactly what you want, but this info should
point you in the right direction. There are lots of books/articles
on how arrays work, so you shouldn't have a problem finding more
information.