Type casting a Number to double

Question

I am trying to compute few calculations for my project and I get following java.lang.ClassCastException for
y2= (double) molWt[x];

molWt and dist are two array of type Number and double respectively.

java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Double

public Double calcData(Number[] molWt, Double[] dist, String unk) {
        Double y2,y1, newY = null;
        Double x1,x2;

        Double unkn = Double.parseDouble(unk.toString());
        Double prev=0d;
        Double slope;


        for (int x = 0; x < dist.length; x++)
            if (unkn > prev && unkn < dist[x]) {
                y2 = (double) molWt[x];
                y1 = (double) molWt[x - 1];

                x2 = dist[x];
                x1 = dist[x - 1];

                slope = ((y2 - y1) / (x2 - x1));

                newY = slope * (unkn - x1) + y1;


            } else {
                prev = dist[x];
            }

        return newY;
    }

Answer 1

Use Number.doubleValue():

y2 = molWt[x].doubleValue();

instead of trying to cast. Number cannot be cast to a primitive double.