Convert a double array to Double ArrayList

When I try to convert a double array to a Double arrayList I got the following error:

Exception in thread "main" java.lan开发者_如何学JAVAg.ClassCastException: [D cannot be cast to java.lang.Double

Below is my code.

double [] firstValueArray ;

ArrayList <Double> firstValueList = new ArrayList (Arrays.asList(firstValueArray));

I am comparing this list with another list and assign the result to another double variable.

Please let me know the reason for this error.

Alas, Arrays.asList(..) doesn't work with primitives. Apache commons-lang has

Double[] doubleArray = ArrayUtils.toObject(durationValueArray);
List<Double> list = Arrays.asList(doubleArray);

Using Java 8 Streams API this is achieved with

DoubleStream.of(doublesArray).boxed().collect(Collectors.toList());

If returning an ArrayList as an implementation is required then use

DoubleStream.of(doublesArray).boxed().collect(Collectors.toCollection(ArrayList::new));

This one-liner doesn't require any additional libraries.

Guava's version is even shorter:

List<Double> list = Doubles.asList(doubleArray);

Reference:

• Doubles.asList(double ...)

Note: This is a varargs method. All varargs methods can be called using an array of the same type (but not of the corresponding boxed / unboxed type!!). These two calls are equivalent:

Doubles.asList(new double[]{1d,2d});
Doubles.asList(1d,2d);

Also, the Guava version doesn't do a full traverse, it's a live List view of the primitive array, converting primitives to Objects only when they are accessed.

Credit to bestsss for the comment which should be the answer:

ArrayList<Double> firstValueList = new ArrayList<Double>();
for(double d : firstValueArray) firstValueList.add(d);

…or with Java 1.7:

double[] firstValueArray = new double[] {1.0, 2.0, 3.0};

ArrayList<Double> list = DoubleStream.of( firstValueArray ).boxed().collect(
    Collectors.toCollection( new Supplier<ArrayList<Double>>() {
      public ArrayList<Double> get() {
        return( new ArrayList<Double>() );
      }
    } ) );