CODEWITHSUNDEEP
javaarraylistclasscastexception
Arash m
Arash m

Reputation: 109

[D cannot be cast to java.lang.Double

I wrote below code. It get this message:

Exception in thread "main" java.lang.ClassCastException: [D cannot be cast to java.lang.Double

double[] xyz = {1, 11, 111, 2, 22, 222};
ArrayList array = new ArrayList();

array.add(xyz);

double[] vals = new double[array.size()];

vals[0] = (double) array.get(0);
vals[1] = (double) array.get(1);
vals[2] = (double) array.get(2);

I have also search and see some post on Stack Overflow, but they do not make much me sense. What should I do?

Upvotes: 0

Views: 7752

Answers (2)

Duncan Jones
Duncan Jones

Reputation: 69349

If you want to add an array of double values to an ArrayList, do this:

Double[] xyz = {...};
ArrayList<Double> array = new ArrayList<>(); // note, use a generic list
array.addAll(Arrays.asList(xyz));

A List cannot store primitives, so you must store Double values not double. If you have an existing double[] variable, you can use ArrayUtils.toObject() to convert it.

Upvotes: 6

damus4
damus4

Reputation: 148

Actually your problem is that you are trying to cast the type of 'xyz', which does not seems to be a double or the Wrapper associed (Double), into a double.

Since java can't transform the type of 'xyz' into a double a ClassCastException is throw. You should try to add n double to your array like that (or even in a loop) :

ArrayList<Double> myListOfDouble = new ArrayList();
myListOfDouble.add(1.0);

And then using a for loop to populate your double[] vals like this :

for(int i = 0; i < myListOfDouble.size(); i++)
    vals[i] = myListOfDouble.get(i);

Upvotes: 4

Related Questions