java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList
JavaArraylistCastingJava Problem Overview
Can you explain me why does this happen and how can I fix it please?
So I'm using Oracle-ADF and I'm using shuttle components. I get the selected values using the sos1.getValue();
The getValue() method returns an object and I'm trying to convert it to an ArrayList so I can work with it later. Therefore I've created the ArrayList sos1Value
However, this line of code is going bananas:
sos1Value = (ArrayList) Arrays.asList(sos1.getValue());
And I keep getting java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList
I've tried other ways like: sos1Value = (ArrayList) sos1.getValue();
But I keep having the same problem, what can I do?
Java Solutions
Solution 1 - Java
Arrays.asList
returns a List
implementation, but it's not a java.util.ArrayList
. It happens to have a classname of ArrayList
, but that's a nested class within Arrays
- a completely different type from java.util.ArrayList
.
If you need a java.util.ArrayList
, you can just create a copy:
ArrayList<Foo> list = new ArrayList<>(Arrays.asList(sos1.getValue());
If you don't need an ArrayList just remove the cast:
List<Foo> list = Arrays.asList(sos1.getValue());
(if you don't need any members exposed just by ArrayList
).
Solution 2 - Java
Arrays.asList(sos1.getValue());
produces an instance of a List implementation (java.util.Arrays$ArrayList
) that is not java.util.ArrayList. Therefore you can't cast it to java.util.ArrayList
.
If you change the type of sos1Value
to List
, you won't need this cast.
If you must have an instance of java.util.ArrayList
, you can create it yourself :
sos1Value = new ArrayList (Arrays.asList(sos1.getValue()));
Solution 3 - Java
The ArrayList
returned by Arrays.asList()
method is NOT java.util.ArrayList
it is a static inner class inside Arrays
class. So, you can't cast it to java.util.ArrayList
.
Try converting / assigning it to a List
.
Solution 4 - Java
The easy way (not efficient) is
ArrayList sos2Value = new ArrayList()
sos2Value.addAll(Arrays.asList(sos1.getValue()))
sos2Value is java.util.ArrayList.
Arrays.asList(sos1.getValue()) is java.util.Arrays$ArrayList
But I'm not clear what you want to do.
Solution 5 - Java
I used it in this way:
private fun getArtists(): ArrayList<ArtistItem> {
var xp = myDb.daoNote().getArtists() as ArrayList<ArtistItem>
val x: List<ArtistItem> = xp.sortedWith(compareBy { it.isBookmarked})
var pp = ArrayList<ArtistItem>()
for(obj in x)
{
pp.add(obj)
}
return pp
}
Solution 6 - Java
java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList
You need to set the type to java.util.List