I have an Item class which contains a code, quantity and amount fields, and a list of items which may contain many items (with same code). I want to group the items by code and sum up their quantities and amounts. I was able to achieve half of it using stream’s groupingBy and reduce. The grouping by wor…
Tag: java
Print all cominations of numbers in ascending order recursively (with length n between 1 and 9)
I want to print all number combinations that are in ascending order. The output should go like: 012, 013, 014, …, 789 for n = 3. I tried to solve it using recursion, however I’m having the StackOverflowError. So it means it never reaches the result. Here is my code so far: Answer There are these i…
Correct Use Of Factory Pattern?
I have been doing research on the factory design pattern and was wondering if the below example, while not “textbook” is technically a correct use of it. Is there another design pattern that may fit the situation better? Answer IMO: Looks like the given code example actually implemented the Factor…
Spring boot “no transaction is in progress” with 2 datasources
I have two databases and i’m trying to save some records to both of them inside a service method. This gives me the error: org.springframework.dao.InvalidDataAccessApiUsageException: no transaction is in progress; nested exception is javax.persistence.TransactionRequiredException: no transaction is in p…
How to generate a random number in Java between x and y where the mean is m? [closed]
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 5 months ago. Improve this question I need to generate random numbers between 100 and 500 where the mean is 1…
Getting a No Serializer Found for class when trying to test a method with ObjectMapper
I am getting this exception – java.lang.IllegalArgumentException: No serializer found for class org.mockito.internal.creation.bytebuddy.ByteBuddyCrossClassLoaderSerializationSupport and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEAN…
Mockito not working when using Model Mapper
I have an User class: And an UpdateUserDTO class: And an UserDTO class: I’ve used Model Mapper to map the updated fields from updateUserDTO to user, which comes from the DB. My test class looks like this: But the first Mockito.when() line does not even compile, because mapper.map() is a void method, so …
How to match the string and click on selenium webdriver
I Have an two string in Auto suggestion Dropdown Like 1. qapostgres112axdef 2. qapostgres112 I need to match the second value (qapostgres112) and need to click on it. for that I used the contains() method. since, both the String contains the same characters ‘qapostgres112’ selenium performs click …
Is it possible to override an inherited method with type parameter List with List?
I’m having trouble changing the type parameter of an inherited method. All animal subclasses need to implement a method animalList. What’s the best practice of doing this if i want the best possible code regarding readability and maintainability? Please note that this is extremely simplified i com…
Uploading json content on s3 using presigned url – gzipped
On the backend i’m generating a presigned url to upload a json object to an s3 bucket. I want the body actual json to be compressed. This is what i’m doing in the backend: Now, in postman, I manually add the content-encoding: gzip header and the file gets uploaded Issues: 1. If i go to the aws con…