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);
}
}