Dynamic use of arrays - Java example

Arrays example from a Well House Consultants training course
More on Arrays [link]

This example is described in the following article(s):
• Java is a dynamic language .... (and comparison) - [link]

This example references the following resources:
http://www.wellho.net/mouth/1498_.html

Source code: rowby.java Module: J705

/* See http://www.wellho.net/mouth/1498_.html for details

Although you cannot extend an array in Java (but you can in
java.lang.util objects such as a Vector and an ArrayList) you
can re-allocate a new array to an existing name. */

public class rowby {

public static void main (String [] args) {

/*
Pascal's Triangle - row by row using previous
and current rows in arrays of those names
*/

        int rows = 15;
        int [] previous, current;
        previous = new int[0];

        for (int k=0; k<rows; k++) {

// Calculate current row based on previous one

                current = new int[previous.length+1];
                current[k]= current[0] = 1;
                for (int j=1; j<previous.length; j++) {
                        current[j] = previous[j-1] + previous[j];
                }

// Output the current row

                for (int c=0; c<current.length; c++) {
                        System.out.print(current[c]);
                        System.out.print(" ");
                }
                System.out.println();

// Make the current row into the previous one

                previous = current;
        }
}
}

/*

Sample output:

[trainee@snowdrop java08]$ java rowby
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1
1 8 28 56 70 56 28 8 1
1 9 36 84 126 126 84 36 9 1
1 10 45 120 210 252 210 120 45 10 1
1 11 55 165 330 462 462 330 165 55 11 1
1 12 66 220 495 792 924 792 495 220 66 12 1
1 13 78 286 715 1287 1716 1716 1287 715 286 78 13 1
1 14 91 364 1001 2002 3003 3432 3003 2002 1001 364 91 14 1
[trainee@snowdrop java08]$

*/

Learn about this subject

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* Learning to Program in Java
* Java Bootcamp
* Java Programming for the Web
Also available on on site courses for larger groups

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Other Examples

This example comes from our "Arrays" training module. You'll find a description of the topic and some other closely related examples on the "Arrays" module index page.

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