casting integer array to object array in java

Question

I am using JDK 1.6 but the second line in the following snippet gives a compile error in Eclipse:

long[] css = new long[]{1, 2, 3};
Object[] objs = Arrays.copyOf(ccs, ccs.length, Object[].class );

Error is: The method copyOf(long[], int) in the type Arrays is not applicable for the arguments (long[], int, Class)

Casting is required for

org.hibernate.criterion.Restrictions.in("PropertyName", objs );

Any ideas or recommended approach?

TIA.

ddmps · Accepted Answer · 2012-12-15 02:21:25Z

9

You can't do that in the java. long is a primitive type, and does because of that not extend Object. Long, which is a wrapper class for long, does and can be cast to an Object. To create a Long[] from a long[] you will need to go through every value of long[] and copy that to Long[]:

long[] primitiveLong;
Long[] wrappedLong = new Long[primitiveLong.length];
for (int i=0; i<primitiveLong.length; i++) {
    wrappedLong[i] = primitiveLong[i];
}

Then you can cast it to an array of Object:

Object[] objs = wrappedLong;

Or you can even make the wrappedLong of type Object directly so you don't need the casting.

edited Dec 15, 2012 at 2:21

answered Dec 13, 2012 at 21:30

ddmps

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6 Comments

Andrew Campbell Over a year ago

+1 I believe that is the requirement for the copyOf method mentioned.

Gili Over a year ago

This is a copy not a cast.

Klaus Nji Over a year ago

Thanks. Is there a quick way to convert from long to Long ? I am working with an API that provides long[] instead of Long[].

Klaus Nji Over a year ago

@Gili, how will I do a cast? I surely cannot do (Long[])new long[]{1,2}

Gili Over a year ago

@KNji, the correct answer is: "What you are asking for is impossible in Java, however you can make a copy like this..."

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djechlin · Accepted Answer · 2012-12-13 21:27:16Z

3

Use Apache Commons' ArrayUtils.toObject which does exactly this.

answered Dec 13, 2012 at 21:27

djechlin

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