Problems with my matrix...

Question

Hi,
I get this error when I try to run through this part of my code:
"java.lang.NullPointerException"
What am I doing wrong?
    int counter1=0, counter2=0, sum=0;
    Double temp1, temp2, result;
    Double[] Array1, Array2;
    Double[][] newMatrix, dmatrix;
            while(counter1 < dmatrix.length) {
            for(int i = 0; i < dmatrix[counter1].length; i++) {
                Array1[i] = dmatrix[counter1]; // <--I believe the errors are here? But it could be due to something else
System.out.println(Array1[i]);
counter2 = counter1 + 1;
while(counter2 < dmatrix.length) {
for(int j = 0; j < dmatrix[counter2].length; j++) {
Array2[j] = dmatrix[counter2][j]; // <--I believe the errors are here? But it could be due to something else
for(int k = 0; k < Array2.length; k++) {
temp1 = Array1[k];
temp2 = Array2[k];
if(temp1.compareTo(temp2) < 0) {
result = new Double (result.doubleValue() + ( temp1.doubleValue()/temp2.doubleValue() ) );
else if(temp1.compareTo(temp2) > 0) {
result = new Double (result.doubleValue() + ( temp2.doubleValue()/temp1.doubleValue() ) );
sum++;
System.out.println(result);
counter1++;
sum = 0;

Answer 1

Double[] Array1, Array2;
Double[][] newMatrix, dmatrix;Wrong. You haven't allocated any memory. Where's the call to new? All you've done is declare variables of a given type.
You need to do something more like this:
public class MatrixTester
    public static void main(String [] args)
        int numRows = 5;
        int numCols = 5;
        double [][] matrix = new double[numRows][];
        for (int m = 0; m < numRows; ++m)
            matrix[m] = new double[numCols];
            for (int n = 0; n < numCols; ++n)
                matrix[m][n] = (double)(m + n);
        for (int m = 0; m < numRows; ++m)
            for (int n = 0; n < numCols; ++n)
                System.out.print(matrix[m][n] + " ");
            System.out.println();
}Note the calls to "new".