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can anyone help me with this programme?
The Programme pretty much works unless I choose to do scalar Multiplication on the 2x3 matrix/array. I then get the error QUOTE]Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
at Practical4.printArray(Practical4.java:254)
at Practical4.main(Practical4.java:127)[/CODE]
the second problem was when using this code to get the output as
a b c
d e f
I get a similar error only when trying to print, add, multiply anything
can anyone help me get this to work?
Code:
import java.io.*;
import java.util.Scanner;
public class Practical4
{
public static void main(String[] args)
{
//NOTE java stored as [row][column]
int optionSelection, arraySelection1, arraySelection2;
int setuparray1 [][] = new int [][] {{7, 8},{3, 1} };
int setuparray2 [][] = new int [][] {{4, 5},{6, 9} };
int setuparray3 [][] = new int [][] {{4, 6, 3},{-1,9,-5}};
optionSelection = getScannerInput.anInt("Please Select the number of what would you like to do?\n1 = Addition,\n2 = Scalar Multiplication,\n3 = Matrix Product\n4 = Print Array\n\n");
//Option for Matrix addition selected
if(optionSelection == 1){
arraySelection1 = getScannerInput.anInt("\nWhat is the first matrix would you like to select?(1,2 or 3)\n");
arraySelection2 = getScannerInput.anInt("What is the Second matrix would you like to select?(1,2 or 3)\n");
//Can be down with a switch statement but due to time I went with a simple if-else for each case
//Combinations needed are 1-2, 1-3, 2-3 and the reverse order being passed so 6 statements for each
//combination and one for error checking
if (arraySelection1 == 1 && arraySelection2 == 2){
matrixAddition(setuparray1, setuparray2);
}
else if (arraySelection1 == 2 && arraySelection2 == 1){
matrixAddition(setuparray2, setuparray1);
}
else if (arraySelection1 == 1 && arraySelection2 == 3){
matrixAddition(setuparray1, setuparray3);
}
else if (arraySelection1 == 3 && arraySelection2 == 1){
matrixAddition(setuparray3, setuparray1);
}
else if (arraySelection1 == 2 && arraySelection2 == 3){
matrixAddition(setuparray2, setuparray3);
}
else if (arraySelection1 == 3 && arraySelection2 == 2){
matrixAddition(setuparray3, setuparray2);
}
else{
System.out.println("not a valid option");
}
}//end of option 1, Addition
//Option 2 Scalar Multiplication
if(optionSelection == 2){
arraySelection1 = getScannerInput.anInt("What is the matrix would you like to select? (1,2 or 3)\n");
arraySelection2 = getScannerInput.anInt("What factor would you like to scale it by?\n");
//all 3 arrays can be passed. Order is already controlled by programme so only an option to pass each array
//needs to be taken into account.
if (arraySelection1 == 1){
scalarMultiplication(arraySelection2,setuparray1);
}
else if (arraySelection1 == 2){
scalarMultiplication(arraySelection2,setuparray2);
}
else if (arraySelection1 == 3){
scalarMultiplication(arraySelection2,setuparray3);
}
}//end of option 2 Scalar Multiplication
// Option 3, Matrix product
if(optionSelection == 3){
arraySelection1 = getScannerInput.anInt("What is the first matrix would you like to select? (1,2 or 3)\n");
arraySelection2 = getScannerInput.anInt("What is the Second matrix would you like to select? (1,2 or 3)\n");
//This is the same as the addition for the combinations that can be passed. Again a switch statement could
// of been used.
//Combinations needed are 1-2, 1-3, 2-3 and the reverse order being passed so 6 statements for each
//combination and one for error checking
if (arraySelection1 == 1 && arraySelection2 == 2){
matrixProduct(setuparray1, setuparray2);
}
else if (arraySelection1 == 2 && arraySelection2 == 1){
matrixProduct(setuparray2, setuparray1);
}
else if (arraySelection1 == 1 && arraySelection2 == 3){
matrixProduct(setuparray1, setuparray3);
}
else if (arraySelection1 == 3 && arraySelection2 == 1){
matrixProduct(setuparray3, setuparray1);
}
else if (arraySelection1 == 2 && arraySelection2 == 3){
matrixProduct(setuparray2, setuparray3);
}
else if (arraySelection1 == 3 && arraySelection2 == 2){
matrixProduct(setuparray3, setuparray2);
}
else{
System.out.println("not a valid option");
}
}//end of option 3, Matrix Product
if(optionSelection == 4){
arraySelection1 = getScannerInput.anInt("What is the matrix would you like to select? (1,2 or 3)\n");
if (arraySelection1 == 1){
printArray(setuparray1);
}
else if (arraySelection1 == 2){
printArray(setuparray2);
}
else if (arraySelection1 == 3){
printArray(setuparray3);
}
}
}
public static void matrixAddition( int[][] a, int[][] b) //a method that implements matrix addition
{
int RowSizeA = a.length;
int RowSizeB = b.length;
int ColumnSizeA = a[0].length;
int ColumnSizeB = b[0].length;
int [][]c;
c = new int [RowSizeA][ColumnSizeA];
//Compare array length
if ((RowSizeA == RowSizeB)&&(ColumnSizeA == ColumnSizeB)){
//Carry out addition
for (int column = 0; column < 2; column++){
for (int row = 0; row < 2; row++){
c[row][column] = a[row][column] + b[row][column];
}
}
}
else{
System.out.println("These cannot be added");
return;
}
printArray(c);
return;
}
public static void scalarMultiplication( int factor, int[][] a) //a method that implements scalar multiplicaton
{
int RowSizeA = a.length;
int ColumnSizeA = a[0].length;
int [][]c;
c = new int[RowSizeA][ColumnSizeA] ;
for (int column = 0; column < RowSizeA; column++){
for (int row = 0; row < ColumnSizeA; row++){
c[row][column] = a[row][column] * factor;
}
}
printArray(c);
return;
}
public static void matrixProduct( int[][] a, int[][] b) //a method that implements matrix multiplicaton
{
int total = 0,ProductOfTerms;
int RowSizeA = a.length;
int RowSizeB = b.length;
int ColumnSizeA = a[0].length;
int ColumnSizeB = b[0].length;
int [][]c;
c = new int[RowSizeA][ColumnSizeB];
if (ColumnSizeA == RowSizeB){
//Go along the row in matrix one and down the column of matrix two adding the results.
//Then Go along the row again adding the results for the second column of Matrix B
//Repeat for Row two of matrix A for all rows
//This is done by:-
//ColumnMatrixOne is used to select RowMatrixTwo (inner loop)
//ColumnMatrixTwo selects the next column of Matrix 2
//RowMatrixOne is used to select the next row of matrix 1 after all column terms in second matrix are totaled
for (int RowMatrixOne = 0; RowMatrixOne < a.length; RowMatrixOne++){
for(int ColumnMatrixTwo = 0; ColumnMatrixTwo < b[0].length; ColumnMatrixTwo++){
for (int ColumnMatrixOne = 0; ColumnMatrixOne < a[0].length; ColumnMatrixOne++){
ProductOfTerms = a[RowMatrixOne][ColumnMatrixOne] * b[ColumnMatrixOne][ColumnMatrixTwo];
total = total + ProductOfTerms;
}
c[RowMatrixOne][ColumnMatrixTwo] = total;
total = 0;
}
}
printArray(c);
}
else {
System.out.println("These matrix can't be multiplied together");
return;//need to return to main
}
return;
}
public static void printArray(int [][] c) //prints the contents of a 2D array
{
System.out.println("\n");
for(int row = 0; row < c.length; row++){
for(int column = 0; column < c[0].length; column++){
System.out.println(c[row][column]);
}
}
return;
}
}The Programme pretty much works unless I choose to do scalar Multiplication on the 2x3 matrix/array. I then get the error QUOTE]Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
at Practical4.printArray(Practical4.java:254)
at Practical4.main(Practical4.java:127)[/CODE]
the second problem was when using this code to get the output as
a b c
d e f
Code:
public static void printArray(int [][] c) //prints the contents of a 2D array
{
System.out.println("\n");
int arrayColumnSize = c[0].length;
if (arrayColumnSize == 1){
for(int row = 0; row < c.length; row++){
System.out.println(c[row][1]);
}
}
if (arrayColumnSize == 2){
for(int row = 0; row < c.length; row++){
System.out.println(c[row][1] + "," + c[row][2]);
}
}
if (arrayColumnSize == 3){
for(int row = 0; row < c.length; row++){
System.out.println(c[row][1] + "," + c[row][2] + "," + c[row][3]);
}
}
return;
}I get a similar error only when trying to print, add, multiply anything
can anyone help me get this to work?
Last edited: