How can i store an array inside an array?

Question

Is it possible to declare an array of type String[] array.
I think not, so how you go about it?

I have a for loop in which each iteration returns another array of String type. So that i need to store all those arrays.

EDIT:

Can someone tell me how to print out a two dimensional string array.
The problem is Array[i][j], now here "i" is fixed but "j" keeps changing dpeneding upon the size of array returned in above method.

So how can i proceed further. Any simple printing idea would be a great help.

EDIT:

How can i get the size of [j] index. Array.length; returns the size of [i] index.

EDIT:

Here is how i did it:

for (int i=0; i< files.length; i++){
    for (int j=0; j<files[i].length; j++){
            System.out.println("["+i+"]["+j+"] = "+ files[i][j]);
        }
    }
}

There is no such thing as "the size of [j] index". Every String[] in a String[][] may have its own, separate length. — Karl Knechtel
– Karl Knechtel, Commented Dec 27, 2010 at 16:28
@Karl, So that means there is no way to check out how many elements are stored against each [i]? If this is the case, i can not have any general set of code to display the results. Everytime i get NullPointer Exception. I think i would have to use Linked LIsts here. — David
– David, Commented Dec 27, 2010 at 16:35
@Karl, you were WRONG. I figured out the way. In each iteration i can use Array[i].length; to get size of [j] index. I would appreciate if you could avoid giving wrong idea. If you don't know something, please don't raise confusion and time wastage for others. — David
– David, Commented Dec 27, 2010 at 16:39
I said nothing wrong. Read it again: "Every String[] in a String[][] may have its own, separate length". That is why, "in each iteration, [you] can use Array[i].length" to get the length of that String[]. I know exactly what I'm talking about, and your time was very well spent, as you figured out what to do. Your terminology was simply a bit off. BTW, NullPointerExceptions have nothing to do with the problem of figuring out how long each row is. They came about because a String[][] holds String[] objects, and a String[] can be null, and x[i] is invalid when x is null. — Karl Knechtel
– Karl Knechtel, Commented Dec 27, 2010 at 17:55

npinti · Accepted Answer · 2010-12-27 15:54:55Z

2

You might be referring to 2 dimensional arrays. A very quick tutorial is available here.

answered Dec 27, 2010 at 15:54

npinti

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1 Comment

David Over a year ago

Thanks, what confused me i thought by multidimensional they are really "multidimensional". It seems in java they really an array of another array.

Bozho · Accepted Answer · 2010-12-27 15:54:36Z

1

Yes - it's String[][]. You can also have 3-dimensional array with [][][]

On the other hand, you can use a List<List<X>>.

answered Dec 27, 2010 at 15:54

Bozho

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Matthew Flynn · Accepted Answer · 2010-12-27 15:55:06Z

1

String[][] stringArrayArray = new String[5][];
stringArrayArray[0] = new String[10];

etc

answered Dec 27, 2010 at 15:55

Matthew Flynn

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4 Comments

Gursel Koca Over a year ago

stringArrayArray[0][] = new String[10] wrong usage. it should be like that stringArrayArray[0] = new String[10]

David Over a year ago

I think two nested for loops can do the job. How you go about checking the size of 2nd index in a two dimensinal array.

Matthew Flynn Over a year ago

@Gursel Koca - Thanks. I was fixing it as you were commenting.

Matthew Flynn Over a year ago

@David - The second dimension can vary for each member of the first. That is, stringArrayArray[0].length could be 4 and stringArrayArray[1].length could be 19.

Nishant · Accepted Answer · 2010-12-27 15:55:21Z

1

2D arrays are arrays of arrays see here http://www.willamette.edu/~gorr/classes/cs231/lectures/chapter9/arrays2d.htm

answered Dec 27, 2010 at 15:55

Nishant

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Comments

Damian Leszczyński - Vash · Accepted Answer · 2010-12-27 15:57:54Z

1

It can be done.

String[] array = new String[10]; //Array for ten String objects.

String[][] arrayOfArrays = new String[10][]; //Array for ten String arrays.


arrayOfArrays[0] = array; // Under index 0 we assign the reference to array.

Another approach is to use List class.

   List<String[]> listofArrays = new ArrayList<String[]>();

   listofArrays.add(array):

answered Dec 27, 2010 at 15:57

Damian Leszczyński - Vash

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