Java Tutorial/Collections/Multidimensional Arrays

Array Of int Arrays

   <source lang="java">

/*

* Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in the
*     documentation and/or other materials provided with the distribution.
*
*   - Neither the name of Sun Microsystems nor the names of its
*     contributors may be used to endorse or promote products derived
*     from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

public class ArrayOfArraysDemo2 {

 public static void main(String[] args) {
   int[][] aMatrix = new int[4][];
   // populate matrix
   for (int i = 0; i < aMatrix.length; i++) {
     aMatrix[i] = new int[5]; // create sub-array
     for (int j = 0; j < aMatrix[i].length; j++) {
       aMatrix[i][j] = i + j;
     }
   }
   // print matrix
   for (int i = 0; i < aMatrix.length; i++) {
     for (int j = 0; j < aMatrix[i].length; j++) {
       System.out.print(aMatrix[i][j] + " ");
     }
     System.out.println();
   }
 }

}</source>

Array Of string Arrays

   <source lang="java">

/*

* Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in the
*     documentation and/or other materials provided with the distribution.
*
*   - Neither the name of Sun Microsystems nor the names of its
*     contributors may be used to endorse or promote products derived
*     from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

public class ArrayOfArraysDemo {

 public static void main(String[] args) {
   String[][] cartoons = {
       { "Flintstones", "Fred", "Wilma", "Pebbles", "Dino" },
       { "Rubbles", "Barney", "Betty", "Bam Bam" },
       { "Jetsons", "George", "Jane", "Elroy", "Judy", "Rosie", "Astro" },
       { "Scooby Doo Gang", "Scooby Doo", "Shaggy", "Velma", "Fred", "Daphne" } };
   for (int i = 0; i < cartoons.length; i++) {
     System.out.print(cartoons[i][0] + ": ");
     for (int j = 1; j < cartoons[i].length; j++) {
       System.out.print(cartoons[i][j] + " ");
     }
     System.out.println();
   }
 }

}</source>

Arrays of Arrays

   <source lang="java">

public class MainClass public class MainClass {

 public static void main(String[] args) {
   float[][] t = new float[10][365]; // Temperature array
   for (int i = 0; i < t.length; i++) {
     for (int j = 0; j < t[i].length; j++) {
       t[i][j] = (float) (45.0 * Math.random() - 10.0);
     }
   }
   float average = 0.0f;
   for (int i = 0; i < t.length; i++) {
     for (int j = 0; j < t[i].length; j++) {
       average += t[i][j];
     }
   }
   System.out.println(average);
 }

}</source>

44505.707

Arrays of Arrays in Varying Length

   <source lang="java">

public class MainClass {

 public static void main(String[] arg) {
   float[][] samples = new float[6][]; // Define 6 elements,
   // each is an array
   for (int i = 0; i < samples.length; i++) {
     samples[i] = new float[i + 1]; // Allocate each array
   }
   
   for (int i = 0; i < samples.length; i++) {
     System.out.println(samples[i].length);
   }
   
 }

}</source>

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Defining Multidimensional Arrays

   <source lang="java">

public class MainClass {

 public static void main(String[] arg) {
   long[][][] beans = new long[5][10][30];
   for (int i = 0; i < beans.length; i++) { 
     for (int j = 0; j < beans[i].length; j++) {
       beans[i][j] = new long[(int) (1.0 + 6.0 * Math.random())];
     }
   }
 }

}</source>

Get array upperbound

   <source lang="java">

public class Main {

 public static void main(String args[]) {
   String[][] data = new String[3][4];
   System.out.println("Dimension 1: " + data.length);
   System.out.println("Dimension 2: " + data[0].length);
 }

} /* Dimension 1: 3 Dimension 2: 4

• /</source>

Initialize a two-dimensional array in matrix

   <source lang="java">

public class MainClass {

 public static void main(String args[]) {
   double m[][] = {
     { 0*0, 1*0, 2*0, 3*0 },
     { 0*1, 1*1, 2*1, 3*1 },
     { 0*2, 1*2, 2*2, 3*2 },
     { 0*3, 1*3, 2*3, 3*3 }
   };
   int i, j;
  
   for(i=0; i<4; i++) {
     for(j=0; j<4; j++)
       System.out.print(m[i][j] + " ");
     System.out.println();
   }
 }

}</source>

0.0 0.0 0.0 0.0 
0.0 1.0 2.0 3.0 
0.0 2.0 4.0 6.0 
0.0 3.0 6.0 9.0

To get the number of dimensions

   <source lang="java">

public class Main {

 public static void main(String args[]) {
   String[][] data = new String[3][4];
   System.out.println(getDimension(data));
 }
 public static int getDimension(Object array) {
   int dim = 0;
   Class c = array.getClass();
   while (c.isArray()) {
     c = c.getComponentType();
     dim++;
   }
   return (dim);
 }

} //2</source>