Why does the code above compile at all? Phone seems unrelated to Roamable to me? yes because Roamable is an interface it might cause a Run-time exception but not compile time exception, because even if Phone doesn’t implement Roamable, a subclass of Phone might, hence the compiler has no way to know it but at … Read more
ArrayType is represented in a Row as a scala.collection.mutable.WrappedArray. You can extract it using for example val arr: Seq[Double] = r.getAs[Seq[Double]](“x”) or val i: Int = ??? val arr = r.getSeq[Double](i) or even: import scala.collection.mutable.WrappedArray val arr: WrappedArray[Double] = r.getAs[WrappedArray[Double]](“x”) If DataFrame is relatively thin then pattern matching could be a better approach: import org.apache.spark.sql.Row … Read more
By using a cast you’re essentially telling the compiler “trust me. I’m a professional, I know what I’m doing and I know that although you can’t guarantee it, I’m telling you that this animal variable is definitely going to be a dog.” Since the animal isn’t actually a dog (it’s an animal, you could do … Read more
Your problem is caused by the following facts: Java generics are compiletime syntactic sugar and completely absent during runtime. EL expressions runs during runtime and not during compiletime. HTTP request parameters are obtained as Strings. Logical consequence is: EL doesn’t see any generic type information. EL doesn’t see a List<Long>, but a List. So, when … Read more
This happens when two different ClassLoader objects load classes with the same name. The equality of two classes in Java depends on the fully qualified name and the class loader that loaded it. So if two independent class loaders load classes from the same location, then objects of those types will not be able to … Read more
You’re basically physically including Tomcat 10.x specific libraries in WAR and then deploying the WAR to Tomcat 9.x. This is not the correct approach at all. Moreover, Tomcat 10.x was the first version to be Jakartified, not Tomcat 9.x. Tomcat 9.x For your Tomcat 9.x, which is based on Servlet 4.0, JSP 2.3, EL 3.0, … Read more
Philippe Riand explaned this by email: This class cast happens because the same class had been loaded twice by 2 different class loaders. Thus, from a Java standpoint, they are different and the cast fails. Now, each XPages application is having its own classloader. But this class loader is discarded each time a design change … Read more
Foo<Double> f = new Foo<Double>(); When you use this version of the generic class Foo, then for the member variable a, the compiler is essentially taking this line: private T[] a = (T[]) new Object[5]; and replacing T with Double to get this: private Double[] a = (Double[]) new Object[5]; You cannot cast from Object … Read more
This can happen if two different classloaders load a class named AutocompleteResult. These two classes are then treated as entirely different classes, even if they have the same package and name (and even implementation/fields/methods). A common cause for this is if you use some kind of plugin system and both your base classes and the … Read more
You are passing the Application Context not the Activity Context with getApplicationContext(); Wherever you are passing it pass this or ActivityName.this instead. Since you are trying to cast the Context you pass (Application not Activity as you thought) to an Activity with (Activity) you get this exception because you can’t cast the Application to Activity … Read more