Re: System.arraycopy (2 dim array) and growth of 2 dim array

From:
"hiwa" <HGA03630@nifty.ne.jp>
Newsgroups:
comp.lang.java.programmer
Date:
11 Nov 2006 01:22:39 -0800
Message-ID:
<1163236959.146760.76350@h48g2000cwc.googlegroups.com>
Denis Palas wrote:

Hi everybody

I am working on a program which contains a module that can perform Cartesian
product on number of sets.
The code I have developed so far is :

import java.lang.reflect.Array;

public class Cart5 {

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

{

int pubnewlength;

// declare SolArray
int[][] solArray;

// initialize solArray
solArray=new int[1][4];

// Use for method

for (int ii=0 ; ii<4 ; ii++)
solver(solArray,ii);

// Print the array ?
System.out.println("\n The array was changed ... " );

} // End main

// --------------------------------------------------------------------------

public void solver(int Solarray2[][] , int abi)

{

int[][] A = { {1,2,3,5},
                  {4,6,7},
                  {11,22,9,10},
                  {17,33}
                       };

  jointwoArrays(solarray2,A,abi);

// some other operations

} // End Solver method

// ------------------------------------------------------------------------------

public void jointwoArrays(int solarray3[][] , int aArray[][],int indexA)

{

int y,u;
int[][] tempArray;

// calculate growth of rows:
pubnewlength=solArray3.length * aArray[indexA].length;

//Fill TempArray
y=solArray3[0].length;
u=solArray3.length;
tempArray=new int[u][y];

// Use system.arraycopy to copy solArray3 into tempArray -- How ?

// Change the size of arrow to proper size -- How ?
solArray3 = (int[][]) arrayGrow(solArray3);

// Join operation - Still under construction
for(int i = 0, k = 0; i < tempArray.length; i++)
               for(int j = 0; j < set3.length; j++)

                           {
                                 for (q=0;q<=2;q++)
                                  { solArray3[k][q] = tempArray[i][q];}

                                 solArray3[k][q]= aArray[indexA][j];
                                 ++k;

                           }

} // End jointwoArrays method

// -----------------------------------------------------------------------------------

// This module is from
http://www.java2s.com/ExampleCode/Language-Basics/Growarray.htm

    static Object arrayGrow(Object a) {
    Class cl = a.getClass();
    if (!cl.isArray())
      return null;
    Class componentType = a.getClass().getComponentType();
    int length = Array.getLength(a);
    int newLength = pubnewlength;

    Object newArray = Array.newInstance(componentType, newLength);
    System.arraycopy(a, 0, newArray, 0, length);
    return newArray;
  }

} // End Class

I deeply appreciate your help with these 3 questions :

1. How can I use system.arraycopy to copy my two dimensional array? I have
searched but examples seem to be about one dim arrays.

2. How can I change the "static Object arrayGrow(Object a)" , to grow my two
dimensional array ?

3. If you know any codes or articles or java code regarding Cartesian
products , please tell me.

Thank you
Denis

There are unknown elements in your current code and your requiremen for
the application is also unclear. However, usage of System.arrayCopy()
is simple:

for (int i = 0; i < tempArray.length; ++i){
      System.arrayCopy(solArray3[i], 0, tempArray[i], 0,
solArray3[i].length);
}

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