I have these classes in the library:
// This is java
public abstract class Property<T extends Comparable<T>> {
public static Property<T> create(String str) { /* Some code */ }
}
public class PropertyInt extends Property<Integer> {
public static PropertyInt create(String str) { /* Some code */ }
}
public class PropertyDouble extends Property<Double> {
public static PropertyDouble create(String str) { /* Some code */ }
}
and there is a method that takes a list of Property
s that I want to use:
public void state(Property... properties) {
/* some code */
}
I cannot change the above since they are from a library. In scala, I have the following code which attempts to pass an array to void state(Property...)
:
// This is scala
val propertyInt = PropertyInt.create("index")
val propertyDouble = PropertyDouble.create("coeff")
state(Array[Property](proeprtyInt, propertyDouble)))
The last line of code has an error: Type mismatch, expected Property[_ <: Comparable[T]], actual Array[Property]
How do I fix this?
Note: This is a simplified version of some more complicated code. In the real code, Property<T extends Comparable<T>>
implements the interface IProperty<T extends Comparable<T>>
and IProperty
is taken as the arguments for state
.
Edit: The following
val properties = Array(propertyInt.asInstanceOf[IProperty[_ <: Comparable[_]]],
propertyDouble.asInstanceOf[IProperty[_ <: Comparable[_]]])
state(properties)
Gives the error
Error:(54, 33) type mismatch;
found : Array[Property[_ >: _$3 with _$1 <: Comparable[_]]] where type _$1 <: Comparable[_], type _$3 <: Comparable[_]
required: Property[?0] forSome { type ?0 <: Comparable[?0] }
state(properties)
^
What you need is to change the state
arguments to be generic:
public static void state(Property<?> ... properties) {
/* some code */
}
Then you can do:
// This is scala
val propertyInt = PropertyInt.create("index")
val propertyDouble = PropertyDouble.create("coeff")
state(propertyInt, propertyDouble)
state(Array(propertyInt, propertyDouble):_*)
Upd if you can't change the signature of state
, you can still call it like this:
state(Array[Property[_]](propertyInt, propertyDouble):_*)
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