Lil Villa Posts - Answer Overflow

Lil Villa

•Created by Lil Villa on 5/30/2025 in #java-help

Proper OOP patterns practices with factory

Hey everyone! 👋 I'm working on a feature to decorate API responses with currency formats based on user config (from S3). I initially handled validation and decoration with simple singletons, since I'm actually writing code in Scala, I'm trying to follow fp practices and use singleton to create something where to place a function for logic. My idea to not overcomplicate things and just use plain functions, since this is a very simple feat imo. A new team lead has recently joined my team. He asked me to refactor my pr using Factory class for creating a "currency plugin" instance. The proposed logic for this Factory is: 1. The Factory would be invoked/relevant only if the search query requests currency formats. (The lead's note said: "If search query is requesting currency formats -> None" which I interpret as the factory's specific logic below only applies if currency is requested, otherwise this specific factory/plugin isn't engaged for its primary purpose). 2. If currency format is requested, but the necessary user currency configuration is missing from S3 -> The Factory itself should throw a hard error. This error would occur during the initial request processing and validation phase. 3. If currency formats are requested and the configuration exists -> The Factory creates and returns the plugin instance. My main question is about point 2: Is it a good practice for a Factory class to be responsible for input validation logic? I'm confused, because I think factory should only be responsible for creating object instances which then in turn are supposed to do validation, transformations and so on... And I also think that factories should not be used when there's only two classes in the domain. What are your thoughts on a Factory performing this type of validation leading to a hard stop? Is this a common or advisable pattern, or should such critical validation remain separate from the Factory's creation logic? Thanks for any insights! 🙏

15 replies

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•Created by Lil Villa on 12/27/2023 in #java-help

Change order of log4j2 configuration files properties precedence

I have gradle project which has log4j2.properties file in its resources directory. I've created integration-tests directory with another resources directory and log4j2.xml file. When I run my integrations tests, at first log4j2.xml configuration is used, but once test make a call to main project files xml configuration is being overwritten by log4j2.properties file. How could I make xml file properties take precedence over main project properties file when running tests?

4 replies

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•Created by Lil Villa on 5/29/2023 in #java-help

Can't resolve transitive dependencies by myself

I have a flink project. Which has transitive guava dependencies. Simplified it looks like this:

+--- foo
|  +--- bar
|  |   +--- guava:1.5
|  +--- biz
|  |   +--- guava:1.3

+--- foo
|  +--- bar
|  |   +--- guava:1.5
|  +--- biz
|  |   +--- guava:1.3

If I set 1.5, it ruins biz and if I set 1.3 it ruins bar (these versions do not represent my real project and i put them here just as an example) How to force gradle to set exact dependencies for dependencies dependencies?

9 replies

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•Created by Lil Villa on 5/4/2023 in #java-help

Flink ShutdownHookManager throws Trying to access closed classloader when destroying itself

8 replies

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•Created by Lil Villa on 11/29/2022 in #java-help

Force Spring Yaml configuration environment parameter to be treated as yaml instead of String

Intro: I have a Spring Boot application with its configuration set up with application.yml file like so: - Scala class:

@ConfigurationProperties(prefix = "foo.bar")
@ConstructorBinding
case class MyConfig(
  biz: String,
  testYamlMaps: java.util.Map[String, String]
)

@ConfigurationProperties(prefix = "foo.bar")
@ConstructorBinding
case class MyConfig(
  biz: String,
  testYamlMaps: java.util.Map[String, String]
)

- application.yml:

foo:
  bar:
    biz: "hello"
    test-yaml-maps: ${YAML_TEST_MAP} # option 1
    # test-yaml-maps: {redelivery: true, secure: false} option 2

foo:
  bar:
    biz: "hello"
    test-yaml-maps: ${YAML_TEST_MAP} # option 1
    # test-yaml-maps: {redelivery: true, secure: false} option 2

- YAML_TEST_MAP environment variable:

$ echo $YAML_TEST_MAP 
{redelivery: true, secure: false}

$ echo $YAML_TEST_MAP 
{redelivery: true, secure: false}

Problem: Option 2 works but with option 1 it looks like Spring is parsing application.yml first and only then substitutes environment values this way treating YAML_TEST_MAP as a String making it throw this error:

No converter found capable of converting from type [java.lang.String] to type [java.util.Map<java.lang.String, java.lang.String>]

No converter found capable of converting from type [java.lang.String] to type [java.util.Map<java.lang.String, java.lang.String>]

Question: Is there a way to force Spring replace environment variables first and only then parse? Is there a way to tell Spring to treat value as a rest of yaml document?

7 replies

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•Created by Lil Villa on 10/11/2022 in #java-help

how to add Log4J json template layout

https://logging.apache.org/log4j/2.x/manual/json-template-layout.html says:

Adding log4j-layout-template-json artifact to your list of dependencies is enough to enable access to JsonTemplateLayout in your Log4j configuration:

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-layout-template-json</artifactId>
    <version>2.19.0</version>
</dependency>

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-layout-template-json</artifactId>
    <version>2.19.0</version>
</dependency>

Where should I be looking for my list of dependencies? Should it be my gradle file? Should I be looking at log4j.xml?

6 replies

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