How to solve this ERROR: Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.rangeCheck(ArrayList.java:657) at java.util.ArrayList.get(ArrayList.java:433)..

Here is JAVA code:

import java.io.*; import java.util.*; import java.util.stream.*;

public class MartixMul{ public static void main(String [] args){ BufferedReader breader = null; BufferedWriter bwriter = null; FileWriter fwriter = null; List mylist = new ArrayList<>(); int row1,column1,row2,column2; try { Scanner sc = new Scanner(new File("C:/Users/andrew/Desktop/New folder/jj.txt")); // adds numbers from .txt to ArrayList numbers

while(sc.hasNextInt()){ mylist.add(sc.nextInt()); } } catch(FileNotFoundException e){ System.err.println("Unable to find the file: fileName"); } row1 = mylist.get(0); column1 = mylist.get(1); row2 = mylist.get(2); column2 = mylist.get(3);

if(column1 != row2){ System.out.println("Column 1 is not equal to row 2. Matrix Multiplication is not possible."); try{ fwriter = new FileWriter(new File("mytextfile.txt")); fwriter.write(String.format("Column 1 is not equal to row 2. Matrix Multiplication is not possible.")); fwriter.close(); }catch(Exception e){ System.out.println("NONE"); } }else{ //checking to see if they hold the right numbers System.out.println("Matrix 1 has " + row1 + " rows and " + column1+ " columns"); System.out.println("Matrix 2 has " + row2 + " rows and " + column2+ " columns"); // This puts the first four numbers as the dimensions of int [][] int [][] matrix1 = new int [row1][column1]; int [][] matrix2 = new int [row2][column2];

// Removes the first four numbers from the List which are used as dimensions mylist.remove(0); mylist.remove(0); mylist.remove(0); mylist.remove(0); // This fills the matrix[][]'s up with the numbers in the List int iter = 0; // iterates the index of the List for( int row = 0; row < matrix1.length; row++){ for( int col = 0; col < matrix1[row].length;col++){ matrix1[row][col]= mylist.get(iter); iter++; } } for( int row = 0; row < matrix2.length; row++){ for( int col = 0; col < matrix2[row].length;col++){ matrix2[row][col]= mylist.get(iter); iter++; } } System.out.println("The elements in Matrix 1 are:"); System.out.println(Arrays.deepToString(matrix1)); System.out.println("The elements in Matrix 2 are:"); System.out.println(Arrays.deepToString(matrix2));

int[][] multi = multiply(matrix1, matrix2); System.out.println("Product of Matrix 1 and Matrix 2 is: "); for (int i = 0; i < multi.length; i++) { for (int j = 0; j < multi[0].length; j++) { System.out.print(multi[i][j] + " "); } } try{ fwriter = new FileWriter(new File("MatrixMultiplication.txt")); fwriter.write(String.format ("Matrix 1 has " + row1 + " rows and " + column1+ " columns")); fwriter.write(System.lineSeparator()); //new line fwriter.write(String.format ("Matrix 2 has " + row2 + " rows and " + column2+ " columns")); fwriter.write(System.lineSeparator()); //new line fwriter.write(String.format("The elements in Matrix 1 are:")); fwriter.write(System.lineSeparator()); //new line fwriter.write(String.format(Arrays.deepToString(matrix1))); fwriter.write(System.lineSeparator()); //new line fwriter.write(String.format("The elements in Matrix 2 are:")); fwriter.write(System.lineSeparator()); //new line fwriter.write(String.format(Arrays.deepToString(matrix2))); fwriter.write(System.lineSeparator()); //new line fwriter.write(String.format("Product of Matrix 1 and Matrix 2 is: ")); fwriter.write(System.lineSeparator()); //new line

for (int i = 0; i < multi.length; i++) { for (int j = 0; j < multi[0].length; j++) { fwriter.write(String.format(multi[i][j] + " ")); } } fwriter.close(); }catch(IOException ex) { ex.printStackTrace(); }

} } // Multiplication of matrix public static int[][] multiply(int[][] a, int[][] b) { int rowsInA = a.length; int columnsInA = a[0].length; // same as rows in B int columnsInB = b[0].length; int[][] c = new int[rowsInA][columnsInB]; for (int i = 0; i < rowsInA; i++) { for (int j = 0; j < columnsInB; j++) { for (int k = 0; k < columnsInA; k++) { c[i][j] = c[i][j] + a[i][k] * b[k][j]; // Multiplication of matrices } } } return c; } }