I want to compare 2 objects and create a new one with the values of the second if its values are not null. Otherwise the values of the first one should be copied to the object created. My problem is that I don’t know how to set the value which I want to copy. I know that to get the
Tag: reflection
Sorting an array of classes based only on field name
I have an application where a user provides me with the name of a field, e.g name or costInCents, and I have to sort by that field. I have ways of guaranteeing that the field name will be correct. This application causes the complication that I simply cannot make my class Comparable and implement a specific c…
Generics and reflection in Java. Classes
I have a task where I have to implement method of creating object of the given class. How should I implement this method correctly? I tried to do it in this way But it always throws NoSuchMethodException. Moreover, from the task “It’s guaranteed that all subclasses of Bakery will have public para…
Akka Quickstart: An illegal reflective access operation has occurred
When running the official Akka Quickstart on my Mac terminal, I get this error: Is this the intended result? How can I go about fixing this? Answer This is a warning, not an error. Here is a quote from Oracle JDK 9 Migration Guide https://docs.oracle.com/javase/9/migrate/toc.htm#JSMIG-GUID-7BB28E4D-99B3-4078-…
Why is `getDeclaredAnnotations()` returning an empty list when an annotation is present?
The Javadocs entry for getDeclaredAnnotations say the following: Returns annotations that are directly present on this element. This method ignores inherited annotations. If there are no annotations directly present on this element, the return value is an array of length 0. The caller of this method is free t…
deep copy using reflection java
I can’t get a container from the class field using reflection. I tried the method below, but got an exception: I don’t want to use methods of copying via serialization, I’m interested in reflection. Answer You are doing this for training I hope? If not then use some opensource library, it…
How to fix this unchecked assignment warning?
I got Warning:(31, 46) Unchecked assignment: ‘java.lang.Class’ to ‘java.lang.Class<? extends PACKAGE_NAME.Block>’ warning on the line blockRta.registerSubtype(c);, but I can’t figure out how to fix that without supressing it. ReflectionHelper.getClasses is a static method t…
Referencing packages in java without using String
Is there a way to reference a package in java in code without using a String? Let me explain myself: I’ve a function that fetches all object contained in a package, but I’ve to reference that package using a String, lets say “com.google.guava”. This works, however, If I change the pack…
Scanner TypeAnnotationsScanner was not configured, when used from a referenced library
I have a class which uses org.reflections.Reflections to get annotations in classes in the class path. When i use it in the same project everything works fine, but when i export it as a JAR and refer it in a different class i get the below execption: Here is the code snippet: I do provide a TypeAnnotationsSca…
How to check if a class has overriden a default method from an interface using Reflection in Kotlin or Java?
I have an interface with a default method, and two classes which implement this interface. One of the classes overrides the default method, and the other does not. I get access to the giveHello method using reflection like this: There’s one weird thing here. The polite class does not override the giveHe…