Java cast and convert

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How do I convert ValueCallback<Uri> for ValueCallback<Uri[]>?

java type-conversion cast

  • see if this can help you: http://stackoverflow.com/questions/10296734/image-uri-to-bytesarray?answertab=votes#tab-top

  • No... but thank you.

  • 1

    You can’t make a simple cast because types are not compatible. Provide more details regarding the problem so that we can help better.

1 answer

1

You cannot do this conversion for 3 reasons.

1 - You can only cast if there is a extends or Implements relation between classes. Ex:

public class Animal {

}

public class Cachorro extends Animal {

}

In this case, you can do an upcasting:

Animal animal = new Cachorro();

or a downcasting:

Animal animal = new Cachorro();
   Cachorro cachorro = (Cachorro) animal;

Here is a detail. The cast will only work because the instance of the animal object is a Puppy. If you do it that way:

Animal animal = new Animal();
Cachorro cachorro = (Cachorro) animal;

The downcasting will fail.

2 - In java, we can do something like this:

List<Animal> list = new ArrayList<>();
   ArrayList<Animal> arrayList = (ArrayList<Animal>)list;

But if we try to do it here:

List<Animal> list = new ArrayList<Cachorro>();

An Exception will be launched. Java does not convert the type being used in Generics, only the object that is using Generics which in this case are the Collections.

3 - You are trying to convert Uri to Uri[]. This makes no sense. You cannot convert a common object into a list. At least not via the language cast. What you might want to do is break a single Uri into several Uri. This is not a type conversion. In that case, you will need to create a convert.

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