Is using one class to store data safe?

Question

So I was searching about storing data in one class, and found this. However, that's not what I'm looking for. What I wanted to know about this was whether it's bad practice, can cause performance issues in an application, or if there's another way to do it, etc... (and I'm not doing this on an Android).

Let's say I have a class that stores a HashMap<Enum, Object> and is initialized when I create the class in main.

public Main() {
    // Creates the HashMap, initialized in the constructor 'MemoryContainer'
    MemoryContainer m = new MemoryContainer();
    m.getTestHash().put(SomeEnum.TEST, "Test"); // Using created HashMap
}

Other than casting the value every time I use it, would this cause major issues? If so, is there an alternative?

Answer 1

There's nothing wrong with storing static values in a class, however this is not a good practice.

To store the constants you should create an interface as every field in an interface is already a constant (public static final).

A better approach will be to store these values in properties files, and load them as needed. A properties file can be stored externally and a person who isn't aware of your source code would be able to modify this properties file if needed. For example you can store database connection details in properties files and if server support admin determines that database instance is down, he/she can edit the properties file to point the application to a new one.

Finally for most flexibility you shouldn't store the configuration inside application at all. It can be stored in a database like MySql or in a fast data structure storage like Redis. This will allow multiple instances of your application to share the configuration data and it will also allow you to modify configuration on the fly by modifying them in the database.

Sometimes a Git repository is also used to store this kind of data (like in case of microservices). Git repository in addition to being shared among all the instances, also maintains the history of modifications.