2D array syntax

[anon0ne]

Hello I am making a 2D array however I am wondering what is wrong with the
following syntax.

int[][] parameters = new int[7][5];
parameters[0] = new int[] {1,2,3,4,5};
parameters[1] = new int[] {2,3,4,5,6};
....

I know I could use the following to create the same thing:
int[][] parameters = {{1,2,3,4,5},....,{7,8,9,10,11}};

to get the same effect but I would rather use the initial syntax for what I
am trying to do.
Is there a way where I can achieve this?

thank you for any advice.

 

[Mark Space]

Hello I am making a 2D array however I am wondering what is wrong with the
following syntax.

int[][] parameters = new int[7][5];

Try:

int[][] parameters = new int[5][7];

instead.

parameters[0] = new int[] {1,2,3,4,5};
parameters[1] = new int[] {2,3,4,5,6};
...

 

[Andreas Leitgeb]

Hello I am making a 2D array however I am wondering what is wrong with the
following syntax.
int[][] parameters = new int[7][5];

Try:
int[][] parameters = new int[5][7];
instead.

parameters[0] = new int[] {1,2,3,4,5};
parameters[1] = new int[] {2,3,4,5,6};
...

I guess, you (the OP) got an java.lang.ArrayIndexOutOfBoundsException: 5
at a line like:
parameters[5] = new int[] {42,42,42,42,42};


Anyway, even with Mark's correction, you waste a couple of arrays,
because the initialization already creates a structure of nested
arrays, and the inner ones then get replaced by those later
assignments.

I'd suggest you initialize it as:
int[][] parameters = new int[][7];
unless you intended to replace only a few of them and leave
some/most of the inner arrays unreplaced.

 

[Tom McGlynn]

Hello I am making a 2D array however I am wondering what is wrong with the
following syntax.

int[][] parameters = new int[7][5];
parameters[0] = new int[] {1,2,3,4,5};
parameters[1] = new int[] {2,3,4,5,6};
...

I know I could use the following to create the same thing:
int[][] parameters = {{1,2,3,4,5},....,{7,8,9,10,11}};

to get the same effect but I would rather use the initial syntax for what I
am trying to do.
Is there a way where I can achieve this?

thank you for any advice.

I don't think that there is anything wrong with this (despite Mark's
comments). E.g., the following program runs fine and produces the
expected output.

public class Test {
public static void main(String[] args) throws Exception {

int[][] x = new int[7][5];

x[0] = new int[]{1,2,3,4,5};
x[1] = new int[]{2,3,4,5,6};
x[2] = new int[]{3,3,4,5,6};
x[3] = new int[]{4,3,4,5,6};
x[4] = new int[]{5,3,4,5,6};
x[5] = new int[]{6,3,4,5,6};
x[6] = new int[]{7,3,4,5,6};

for (int i=0; i<x.length; i += 1) {
for (int j=0; j<x.length; j += 1) {
System.out.print(x[j]+" ");
}
System.out.println();
}
}
}

What problems had you seen?

If you are going to build the array piecemeal, then you may wish to
consider Andreas' comment, though I think that you need to invert his
final sets of brackets.

int[][] parameters = new int[7][];


Regards,
Tom McGlynn

 

[John B. Matthews]

Hello I am making a 2D array however I am wondering what is wrong with the
following syntax.

int[][] parameters = new int[7][5];

I think of this as a request for 7 arrays (numbered 0 through 6), each
holding 5 integers (numbered 0 through 4). The initial value of each
parameters is an array reference; the initial value of each
parameters[j] is zero.

Using this approach, I'd defer the column count declaration, as shown
below. This will save allocating 7 arrays, each containing 5 zeros,
which are replaced by your explicit initialization.

parameters[0] = new int[] {1,2,3,4,5};
parameters[1] = new int[] {2,3,4,5,6};

Coming from a number of row-major array order languages, my mental model
is 7 rows and 5 columns, but Java arrays are allowed to vary in length.
As a result, a ragged declaration is permitted, e.g.:

parameters[2] = new int[] {-1,-2,-3};

I know I could use the following to create the same thing:
int[][] parameters = {{1,2,3,4,5},....,{7,8,9,10,11}};

The advantage of this scheme is that the compiler will calculate the
dimensions; the disadvantage is that it will calculate the wrong
dimensions if you skip a value, or add an extra one.

to get the same effect but I would rather use the initial syntax for
what I am trying to do. Is there a way where I can achieve this?

I would encourage you to display the initialization in whatever way
makes most sense to someone reviewing the program's correctness or
maintaining the code as it evolves.

public class Test {

public static void main(String[] args) {
int[][] parameters = new int[7][];
parameters[0] = new int[] {1,2,3,4,5};
parameters[1] = new int[] {1,2,3,4,5};
parameters[2] = new int[] {1,2,3,4,5};
parameters[3] = new int[] {1,2,3,4,5};
parameters[4] = new int[] {1,2,3,4,5};
parameters[5] = new int[] {1,2,3,4,5};
parameters[6] = new int[] {1,2,3,4,5};
}
}

 

[Durango2008]

Hello I am making a 2D array however I am wondering what is wrong with the
following syntax.

int[][] parameters = new int[7][5];
parameters[0] = new int[] {1,2,3,4,5};
parameters[1] = new int[] {2,3,4,5,6};
...

I know I could use the following to create the same thing:
int[][] parameters = {{1,2,3,4,5},....,{7,8,9,10,11}};

to get the same effect but I would rather use the initial syntax for what
I am trying to do.
Is there a way where I can achieve this?

thank you for any advice.

Thank you everyone,
I figured out my problem the syntax is correct I just had it in the wrong
place and
overlooked this easy fix.

 

[blue indigo]

Hello I am making a 2D array however I am wondering what is wrong with the
following syntax.

int[][] parameters = new int[7][5];
parameters[0] = new int[] {1,2,3,4,5};
parameters[1] = new int[] {2,3,4,5,6};

Nothing so far as I can tell, although you're redundantly creating arrays
of five zeros and then replacing them with arrays of nonzero digits. Try
using new int[7][].

P.S. you're not very anonymous. DSL from Southwest Bell in Houston, Texas
and a Prodigy account.

Several free newsservers exist that hide your IP if you want to be more
anonymous. Motzarella.org and aioe.org are two of them. The downside:
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newsserver has downtime. Or if your ISP stops carrying usenet, as so many
of them are doing lately because of a stupid and pointless crusade by some
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Several free newsreaders exist that are much better than what you're
using, too.