CEC-Code-Lab

2D Array Basics

The below command line program demonstrates the basics of 2-dimensional (2D) array declaration, initialization and access. Similar processes are shown for single variables and 1D arrays for comparison.
This code also show the common nested for loop style frequently used to initialize or access a 2D Array.

`Main.java`


public class Main {
    public static void main(String[] args) {
        // declaration and initialization
        char c = 'q';
        char[] cArrayOneD = new char[26];
        char[][] cArrayTwoD = new char[2][26];

        //single assignments
        c = '?';
        cArrayOneD[4] = 'e';
        cArrayTwoD[0][4] = 'E';
        cArrayTwoD[1][4] = 'e';

        //loop assignments
          //1d array
        for (int i = 0; i < cArrayOneD.length; i++) {
            cArrayOneD[i] = (char)('a' + i);
        }
          //2d array
        for (int i = 0; i < cArrayTwoD.length ; i++) {
            for (int j = 0; j < cArrayTwoD[0].length; j++) {
                if(i == 0) cArrayTwoD[i][j] = (char)('A' + j);
                if(i == 1) cArrayTwoD[i][j] = (char)('a' + j);
            }
        }

        //loop print statements
          //1d array
        System.out.println("1D Array Print Loop:");
        String outMsg = new String();
        for (int i = 0; i < cArrayOneD.length; i++) {
            outMsg += cArrayOneD[i] + " ";
        }
        System.out.println(outMsg);
        System.out.println("");

          //2d array
        System.out.println("2D Array Print Loop:");
        outMsg = new String();
        for(int i = 0; i < cArrayTwoD.length; i++){
            for(int j = 0; j < cArrayTwoD[0].length; j++){
                outMsg += cArrayTwoD[i][j] + " ";
            }
            outMsg += '\n';
        }
        System.out.println(outMsg);
    }
}