How can i get non String Array field from SQL query with multiple rows

Question

I have SQL (HSQLDB) table with VALS DOUBLE ARRAY[2000] field I use query that returns multiple rows with VALS field If i try to get array as

Array array = rs.getArray("VALS");
Double[] vals = (Double[]) array.getArray();

i get

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.Double;

I can get values with double conversion from Object to String and then parsing String to Double like:

List<Double> values = new ArrayList<Double>();
for (Object o: (Object[])array.getArray()) {
    values.add(Double.parseDouble(o.toString()));
}

But it looks like heavy overhead

Is there any way to get digits from Array SQL field without String conversion or multiple single-row queries? In debugger rs.getArray() shows me a perfect JDBCArray of digital values ARRAY[0.0E0,0.0E0,0.0E0,0.0E0,0.0E0 .... ]

fredt · Accepted Answer · 2018-01-10 02:01:42Z

1

You don't need to convert to String and back. Just cast:

List<Double> values = new ArrayList<Double>(); 
for (Object o: (Object[])array.getArray()) {
    values.add((Double) o); 
}

answered Jan 10, 2018 at 2:01

fredt

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user1803290 · Accepted Answer · 2018-01-09 16:05:24Z

1

Try the code below:

Double[] vals = Arrays.stream(array.getArray()) .map(Double::valueOf) .toArray(Double[]::new);

answered Jan 9, 2018 at 16:05

user1803290

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1 Comment

Stanislav Orlov Over a year ago

Unresolved compilation problem: The method stream(T[]) in the type Arrays is not applicable for the arguments (Object) If i add cast to Double[] i get the same exception as in the beginning, if i cast to Object[] than i get Unresolved compilation problems: Cannot infer type argument(s) for <R> map(Function<? super T,? extends R>)

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