Flink ElasticsearchSinkFunction not serializable in non-static method, but serializable in static method

I have a piece of code that only works inside static methods. If I put the code in a static method, then call it from a non-static method, it works. Never heard of anything like this and couldn’t find …

How to create Array of Objects using the Jackson Streaming API

I am trying to create a JSON using the Jackson Streaming API. I know how to create an array of elements in JSON using Jackson as we have plenty of examples related to it. But I am a bit confused about …

How do I work with objects in lists and can I create multiple objects with different names in a loop?

I need to create Objects of a class called “Tile”. I have 9×9 chess board like grid and want to initiate the whole board at once. The position of a Tile is defined by an x and y-axis and I …

Java Problem: Calculations in one subclass’ constructor affecting fields of another subclass’ instance

I have two abstract classes i.e. Medicine and Prescription. All code can be found at https://codeshare.io/aVAdr3 These two classes have subclasses, the class hierarchy diagram is as follows: and… …

Compare elements of two arrays of Object

I am trying to build a generic merge method, part of a mergeSort algorithm but I am stuck on how to deal with the comparison. This is my code so far: public static Object[] merge(Object[] left, Object[…

Does it matter if function returns T or object if T can not be inferred from context?

I found the following source code in gson: public T fromJson(Reader json, Type typeOfT) throws JsonIOException, JsonSyntaxException { JsonReader jsonReader = newJsonReader(json); T …

LinkedList inside a LinkedList iteration in java

Im trying to iterate a Linked List inside of a linked list but I’m not sure how to proceed with it. I’m used to using a passed parameter for what will be iterated but when I’m iterating a linked list …

How to add ArrayList parameter to an ArrayList then then add to current class ArrayList

I have an ArrayList called Service that accepts an enum ServiceType, a double price, and an ArrayList Employee. I’m trying to create a method that adds a service element to the Service ArrayList but I’…

Creating multiple objects using the same instance

I just saw this tutorial creating multiple objects using the same instance by applying the DAO pattern and tried it in a simple console, but I always get this message java.lang.NullPointerException I’…

How to assign values to Attributes by passing argument using from method?

I need to assign YEAR, MONTH, DAY attributes to values just only using one set method. therefore I pass DATE.YEAR, DATE.MONTH, DATE.DATE as an argument also with values by calling set method line by …