I am new to writing java code and I would like to improve my skills. I would like someone to review and critic me on where I can improve on. Here is a small program I wrote in java about matrices and a few arithmetic methods applied on it.
import java.util.*;
public class MatrixArithmetic{
private static Scanner in = new Scanner(System.in);
public static void main(String[] args){
menu();
}
public static void menu(){
showOptions();
int choice = getValue();
System.out.println();
while (choice != -1){
switch (choice){
case 1:{ // add two matrices
int size = getSize();
int[][] firstMatrix = getMatrix(size);
int[][] secondMatrix = getMatrix(size);
System.out.println();
System.out.println("First matrix is:");
printMatrix(firstMatrix);
System.out.println("Second matrix is:");
printMatrix(secondMatrix);
int[][] result = addMatrix(firstMatrix, secondMatrix, size);
System.out.println("The resulting matrix is:");
printMatrix(result);
System.out.println();
System.out.println("Command number 1 completed.");
System.out.println();
showOptions();
choice = getValue();
System.out.println();
break;
}
case 2:{ // subtract two matrices
int size = getSize();
int[][] firstMatrix = getMatrix(size);
int[][] secondMatrix = getMatrix(size);
System.out.println();
System.out.println("First matrix is:");
printMatrix(firstMatrix);
System.out.println("Second matrix is:");
printMatrix(secondMatrix);
int[][] result = subMatrix(firstMatrix, secondMatrix, size);
System.out.println("The resulting matrix is:");
printMatrix(result);
System.out.println();
System.out.println("Command number 2 completed.");
System.out.println();
showOptions();
choice = getValue();
System.out.println();
break;
}
case 3:{ // multiply two matrices
int size = getSize();
int[][] firstMatrix = getMatrix(size);
int[][] secondMatrix = getMatrix(size);
System.out.println();
System.out.println("First matrix is:");
printMatrix(firstMatrix);
System.out.println("Second matrix is:");
printMatrix(secondMatrix);
int[][] result = prodTwoMatrix(firstMatrix, secondMatrix, size);
System.out.println("The resulting matrix is:");
printMatrix(result);
System.out.println();
System.out.println("Command number 3 completed.");
System.out.println();
showOptions();
choice = getValue();
System.out.println();
break;
}
case 4:{ // multiply matrix to a constant
int size = getSize();
System.out.print("Enter the multiplication constant: ");
int constant = getValue();
int[][] matrix = getMatrix(size);
System.out.println();
System.out.println("The matrix is:");
printMatrix(matrix);
int[][] result = prodMatrixConstant(matrix, size, constant);
System.out.println("The resulting matrix is:");
printMatrix(result);
System.out.println();
System.out.println("Command number 4 completed.");
System.out.println();
showOptions();
choice = getValue();
System.out.println();
break;
}
case 5:{ // transpose matrix
int size = getSize();
int[][] matrix = getMatrix(size);
System.out.println();
System.out.println("The matrix is:");
printMatrix(matrix);
int[][] result = transposeMatrix(matrix, size);
System.out.println("The resulting matrix is:");
printMatrix(result);
System.out.println();
System.out.println("Command number 5 completed.");
System.out.println();
showOptions();
choice = getValue();
System.out.println();
break;
}
case 6:{ // trace matrix
int size = getSize();
int[][] matrix = getMatrix(size);
System.out.println();
System.out.println("The matrix is:");
printMatrix(matrix);
int result = traceMatrix(matrix, size);
System.out.println();
System.out.print("The trace for this matrix is: " + result);
System.out.println("\n");
System.out.println("Command number 6 completed.");
System.out.println();
showOptions();
choice = getValue();
System.out.println();
break;
}
default:{
System.out.println("Testing completed.");
choice = -1;
break;
}
}
}
}
public static void showOptions(){
System.out.print("Your options are: \n" +
"----------------- \n" +
"1) Add two matrices \n" +
"2) Subtract 2 matrices \n" +
"3) Multiply 2 matrices \n" +
"4) Multiply matrix by a constant \n" +
"5) Transpose matrix \n" +
"6) Matrix trace \n" +
"0) EXIT \n" +
"----------------- \n" +
"Please enter your option: ");
}
public static int getValue(){
return in.nextInt();
}
public static int getSize(){
System.out.print("Enter the size of square matrices: ");
int size = getValue();
return size;
}
public static int[][] getMatrix(int size){
int[][] matrix = new int[size][size];
randMatrix(matrix, size);
return matrix;
}
public static void randMatrix(int[][] matrix, int size){
Random rand = new Random();
for(int i = 0; i < size; i++){
for(int j = 0; j < size; j++){
matrix[i][j] = rand.nextInt(10);
}
}
}
public static void printMatrix(int[][] matrix){
for(int i = 0; i < matrix.length; i++){
for(int j = 0; j < matrix[i].length; j++){
System.out.printf("%4s\t", matrix[i][j]);
}
System.out.print("\n");
}
}
public static int[][] addMatrix(int[][] firstMatrix, int[][] secondMatrix, int size){
int[][] add = new int[size][size];
for(int i = 0; i < size; i++){
for(int j = 0; j < size; j++){
add[i][j] = firstMatrix[i][j] + secondMatrix[i][j];
}
}
return add;
}
public static int[][] subMatrix(int[][] firstMatrix, int[][] secondMatrix, int size){
int[][] sub = new int[size][size];
for(int i = 0; i < size; i++){
for(int j = 0; j < size; j++){
sub[i][j] = firstMatrix[i][j] - secondMatrix[i][j];
}
}
return sub;
}
public static int[][] prodTwoMatrix(int[][] firstMatrix, int[][] secondMatrix, int size){
int[][] product = new int[size][size];
for(int i = 0; i < size; i++) {
for (int j = 0; j < size; j++) {
for (int k = 0; k < size; k++) {
product[i][j] += firstMatrix[i][k] * secondMatrix[k][j];
}
}
}
return product;
}
public static int[][] prodMatrixConstant(int[][] matrix, int size, int constant){
int[][] product = new int[size][size];
for(int i = 0; i < size; i++){
for(int j = 0; j < size; j++){
product[i][j] = matrix[i][j] * constant;
}
}
return product;
}
public static int[][] transposeMatrix(int[][] matrix, int size){
int[][] newMatrix = new int[size][size];
for(int i = 0; i < size; i++){
for(int j = 0; j < size; j++){
newMatrix[i][j] = 0;
for(int k = 0; k < size; k++){
newMatrix[i][j] = matrix[j][i];
}
}
}
return newMatrix;
}
public static int traceMatrix(int[][] matrix, int size){
int trace = 0;
for (int i = 0; i < size; i++){
trace += matrix[i][i];
}
return trace;
}
}
