Java Utililty Methods List to Double Array

final double[] doubles = new double[numbers.size()];
for (int i = 0; i < doubles.length; i++) {
    final Number number = numbers.get(i);
    doubles[i] = number.doubleValue();
return doubles;

return toDoubleArray(list, Double.NaN);

double[] d = new double[a.size()];
for (int i = 0; i < d.length; ++i) {
    d[i] = a.get(i).doubleValue();
return d;

try {
    double[] ret = new double[list.size()];
    for (int i = 0; i < ret.length; i++) {
        ret[i] = list.get(i);
    return ret;
} catch (NullPointerException e) {
    return null;
...

if (isNullOrEmpty(list)) {
    return null;
double[] doubles = new double[list.size()];
for (int i = 0; i < doubles.length; i++) {
    doubles[i] = list.get(i);
return doubles;
...

double[] array = new double[list.size()];
Iterator<Double> ints = list.iterator();
int idx = 0;
while (ints.hasNext()) {
    Double value = ints.next();
    array[idx++] = value.doubleValue();
return array;
...

double[] array = new double[list.size()];
for (int i = 0; i < array.length; i++)
    array[i] = list.get(i);
return array;

double[] array = new double[list.size()];
for (int i = 0; i < list.size(); i++) {
    array[i] = list.get(i);
return array;

double[] res = new double[list.size()];
int index = 0;
for (double d : list) {
    res[index++] = d;
return res;

double ret[] = new double[values.size()];
for (int i = 0; i < ret.length; i++)
    ret[i] = values.get(i);
return ret;