![2
Two-Dimensional Array Basics
Data in a table or a matrix can be represented using a two-dimensional array
element in a two-dimensional array is accessed through a row and column
index
syntax for declaring a two-dimensional array
elementType[][] arrayRefVar; or elementType arrayRefVar[][];
int[][] matrix; or int matrix[][];
matrix = new int[5][5];](https://image.slidesharecdn.com/ch8multidimensionalarray-250630045315-84784f78/85/Ch-8-Multidimensional-Array-in-oop-as-per-gtu-pptx-2-320.jpg)
![6
Obtaining the Lengths of Two-
Dimensional Arrays (Contd…)
The length of an array x is the number of elements in the array, which can be
obtained using x.length
x[0], x[1], . . . , and x[x.length-1]
x[0].length, x[1].length, . . . , and x[x.length-1].length](https://image.slidesharecdn.com/ch8multidimensionalarray-250630045315-84784f78/85/Ch-8-Multidimensional-Array-in-oop-as-per-gtu-pptx-6-320.jpg)
![8
create a ragged array
int[][] triangleArray = new int[5][];
triangleArray[0] = new int[5];
triangleArray[1] = new int[4];
triangleArray[2] = new int[3];
triangleArray[3] = new int[2];
triangleArray[4] = new int[1];](https://image.slidesharecdn.com/ch8multidimensionalarray-250630045315-84784f78/85/Ch-8-Multidimensional-Array-in-oop-as-per-gtu-pptx-8-320.jpg)
![9
Processing Two-Dimensional Arrays
Nested for loops are used to process a two-dimensional array
Initializing arrays with input values
java.util.Scanner input = new Scanner(System.in);
System.out.println("Enter " + matrix.length + " rows and " +
matrix[0].length + " columns: ");
for (int row = 0; row < matrix.length; row++) {
for (int column = 0; column < matrix[row].length; column++) {
matrix[row][column] = input.nextInt();
}
}](https://image.slidesharecdn.com/ch8multidimensionalarray-250630045315-84784f78/85/Ch-8-Multidimensional-Array-in-oop-as-per-gtu-pptx-9-320.jpg)
![12
public class PassTwoDimensionalArray {
public static void main(String[] args) {
int[][] m = getArray(); // Get an array
System.out.println("nSum of all elements is " + sum(m));
}
public static int[][] getArray() {
Scanner input = new Scanner(System.in);
int[][] m = new int[3][4];
System.out.println("Enter " + m.length + " rows and “ + m[0].length + "
columns: ");
for (int i = 0; i < m.length; i++)
for (int j = 0; j < m[i].length; j++)
m[i][j] = input.nextInt();
return m;
}](https://image.slidesharecdn.com/ch8multidimensionalarray-250630045315-84784f78/85/Ch-8-Multidimensional-Array-in-oop-as-per-gtu-pptx-12-320.jpg)
![13
Multidimensional Arrays
two-dimensional array consists of an array of one-dimensional arrays
Three dimensional array consists of an array of two-dimensional arrays
double[][][] scores = new double[6][5][2];
Suppose x = new int[2][2][5]
x[0] and x[1] are two-dimensional arrays
x[0][0], x[0][1], x[1][0], and x[1][1] are one-dimensional arrays and each contains
five elements
x.length is 2
x[0].length and x[1].length are 2
x[0][0].length, x[0][1].length, x[1][0].length, and x[1][1].length are 5](https://image.slidesharecdn.com/ch8multidimensionalarray-250630045315-84784f78/85/Ch-8-Multidimensional-Array-in-oop-as-per-gtu-pptx-13-320.jpg)
Ch 8 Multidimensional Array in oop as per gtu.pptx
- 2. 2 Two-Dimensional Array Basics Data in a table or a matrix can be represented using a two-dimensional array element in a two-dimensional array is accessed through a row and column index syntax for declaring a two-dimensional array elementType[][] arrayRefVar; or elementType arrayRefVar[][]; int[][] matrix; or int matrix[][]; matrix = new int[5][5];
- 3. 3
- 5. 5 Obtaining the Lengths of Two- Dimensional Arrays A two-dimensional array is actually an array in which each element is a one- dimensional array
- 6. 6 Obtaining the Lengths of Two- Dimensional Arrays (Contd…) The length of an array x is the number of elements in the array, which can be obtained using x.length x[0], x[1], . . . , and x[x.length-1] x[0].length, x[1].length, . . . , and x[x.length-1].length
- 7. 7 Ragged Arrays Each row in a two-dimensional array is itself an array. Thus, the rows can have different lengths. An array of this kind is known as a ragged array
- 8. 8 create a ragged array int[][] triangleArray = new int[5][]; triangleArray[0] = new int[5]; triangleArray[1] = new int[4]; triangleArray[2] = new int[3]; triangleArray[3] = new int[2]; triangleArray[4] = new int[1];
- 9. 9 Processing Two-Dimensional Arrays Nested for loops are used to process a two-dimensional array Initializing arrays with input values java.util.Scanner input = new Scanner(System.in); System.out.println("Enter " + matrix.length + " rows and " + matrix[0].length + " columns: "); for (int row = 0; row < matrix.length; row++) { for (int column = 0; column < matrix[row].length; column++) { matrix[row][column] = input.nextInt(); } }
- 10. 10 Processing Two-Dimensional Arrays (Contd…) Other Processes Initializing arrays with random values Printing arrays Summing all elements Summing elements by column Which row has the largest sum?
- 11. 11 Passing Two-Dimensional Arrays to Methods When passing a two-dimensional array to a method, the reference of the array is passed to the method You can pass a two-dimensional array to a method just as you pass a one- dimensional array
- 12. 12 public class PassTwoDimensionalArray { public static void main(String[] args) { int[][] m = getArray(); // Get an array System.out.println("nSum of all elements is " + sum(m)); } public static int[][] getArray() { Scanner input = new Scanner(System.in); int[][] m = new int[3][4]; System.out.println("Enter " + m.length + " rows and “ + m[0].length + " columns: "); for (int i = 0; i < m.length; i++) for (int j = 0; j < m[i].length; j++) m[i][j] = input.nextInt(); return m; }
- 13. 13 Multidimensional Arrays two-dimensional array consists of an array of one-dimensional arrays Three dimensional array consists of an array of two-dimensional arrays double[][][] scores = new double[6][5][2]; Suppose x = new int[2][2][5] x[0] and x[1] are two-dimensional arrays x[0][0], x[0][1], x[1][0], and x[1][1] are one-dimensional arrays and each contains five elements x.length is 2 x[0].length and x[1].length are 2 x[0][0].length, x[0][1].length, x[1][0].length, and x[1][1].length are 5