Define a class Matrix, which represents two-dimensional integer arrays and suppo
ID: 2247872 • Letter: D
Question
Define a class Matrix, which represents two-dimensional integer arrays and supports the following operations. Use the prototype specified in bold below. Use appropriate access modifiers. Create a new Matrix with specified rows and columns: Matrix(int rows, int columns) Convert a Matrix to a string representation so that it can be printed: String getString () For ex if you have the following Matrix [[1, 2], [3, 4]] the string representation should return "1 2 3 " Gettors for row and column. Gettors and Settors for individual elements. int getRow (), int getColumn(). int getValueAt (int row, int column) void setValueAt(int row, int column, int value) Static method: Add two Matrices to get a new Matrix static Matrix add(Matrix one, Matrix other) Multiply a Matrix by an int and return a new Matrix Matrix multipoint x) This will multiply each element of the matrix by x. Compute the diagonal sum of the Matrix as the sum of the elements along the main diagonal, only if the matrix has of rows and columns. Else return Integer.MIN_VALUE Integer getDiagonalSum ()Explanation / Answer
Matrix.java
--------------------------------
public class Matrix {
private int[][] matrix;
// Create a new Matrix with specified rows and columns: Matrix(int rows, int columns)
public Matrix (int rows, int columns) {
matrix = new int[rows][columns];
}
// Convert a Matrix to a string representation so that it can be printed: String getString()
// For ex if you have the following Matrix [[1,2],[3,4]] the string representation should
// return "1 2 3 "
public String getString() {
StringBuilder finalString = new StringBuilder();
for (int rows[] : matrix) {
for (int columns : rows) {
finalString.append(columns);
finalString.append(" ");
}
}
// remove final additional tab at the end and replace with a new line
finalString.replace(finalString.length()-1, finalString.length(), " ");
return finalString.toString();
}
// Returns the number of rows in a matrix
// Package private access to allow the supplied test file to pass
int getRow() {
return matrix.length;
}
// Returns the number of columns in a matrix
// Assuming there is at least one row
// Can set to private because is not called in supplied test file
private int getColumn() {
return matrix[0].length;
}
// Returns the value at a given row and column
// Package private access to allow the supplied test file to pass
int getValueAt(int row, int column) {
return matrix[row][column];
}
// Sets the value at a given row and column to a value
public void setValueAt(int row, int column, int value) {
matrix[row][column] = value;
}
// Add two Matrices to get a new Matrix
// Note: Two matrices can only be added if they have the same number of rows and columns.
// API assumption is both Matrix have the same rows/cols by Problem definition.
public static Matrix add(Matrix one, Matrix other) {
Matrix tempMatrix = new Matrix(one.getRow(), one.getColumn());
for (int i = 0; i < one.getRow(); i++) {
for (int j = 0; j < one.getColumn(); j++) {
tempMatrix.setValueAt(i, j, one.getValueAt(i, j) + other.getValueAt(i, j));
}
}
return tempMatrix;
}
// Multiply a Matrix by an int and return a new Matrix.
public Matrix multiply(int x) {
Matrix tempMatrix = new Matrix(this.getRow(), this.getColumn());
for (int i = 0; i < this.getRow(); i++) {
for (int j = 0; j < this.getColumn(); j++) {
tempMatrix.setValueAt(i, j, this.getValueAt(i, j) * x);
}
}
return tempMatrix;
}
// Compute the diagonal sum of the Matrix as the sum of the elements along
// the main diagonal, only if the matrix has equal number of rows and columns.
// Else return Integer.MIN_VALUE
// Homework instructions has the return as Integer, but tests are looking
// for an int value. Put to int value for the supplied test file to pass.
public int getDiagonalSum() {
int sum = 0;
if (this.getColumn() != this.getRow())
return Integer.MIN_VALUE;
else {
for (int i = 0; i < this.getRow(); i++) {
sum+= this.getValueAt(i, i);
}
}
return sum;
}
}
---------------------------------------------------------------------------
Matrix.java
----------------------------------------------
import static org.junit.Assert.*;
import org.junit.Test;
import java.util.*;
public class MatrixTest {
// Matrix Create
@Test
public void testMatrixCreate() {
Matrix m = new Matrix(10,4);
assertEquals(10,m.getRow());
}
@Test
public void testMatrixString() {
Matrix m = new Matrix(10,4);
m.setValueAt(0,0,10);
m.setValueAt(0,0,-10);
System.out.println(m);
}
@Test
public void testValueSet() {
Matrix m = new Matrix(10,4);
m.setValueAt(0,0,10);
m.setValueAt(1,1,-10);
assertEquals(10,m.getValueAt(0,0));
}
@Test
public void testAdd() {
Matrix m1 = new Matrix(10,4);
m1.setValueAt(0,0,10);
Matrix m2 = new Matrix(10,4);
m2.setValueAt(0,0,10);
Matrix m = Matrix.add(m1, m2);
assertEquals(20,m.getValueAt(0,0));
}
@Test
public void testMultiply() {
Matrix m = new Matrix(10,4);
m.setValueAt(0,0,10);
Matrix m1 = m.multiply(2);
assertEquals(20,m1.getValueAt(0,0));
}
@Test
public void testGetDiagonalSum() {
Matrix m = new Matrix(10,10);
m.setValueAt(0,0,10);
m.setValueAt(1,1,-10);
assertEquals(0,m.getDiagonalSum());
}
}
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