Resetting all attributes of a static class to null?

Question

Java

For example, a class of this kind, which serves as a kind of analogue of a stretch in c ++, there should be 15-20 attributes in total. With an extensive switchcase that will fill in certain attributes of this class. And in order not to constantly reset each of the attributes to 0: attr1 = null, attr2 = null, attr 3 = null .... attr20 = 0, then I thought, in a friend in Java, there is something similar to resetting a memory block as in C .

public static class Test{
    public Long attr1;
    public String attr2;
    public Double attr3;
    public Long attr4;
    private final static Test instanceTest = new Data();
    private Test(){}
  }

Of course, as a last resort, I could write a function that would have to be called in each of the cases, but I would like to find a more elegant solution. Does it exist? Or what would you do in this situation? :)

Answer 1

Null is generally bad. Why do you need a static class if you will change the variables in it anyway, maybe it's better to look towards singletons? Why reset variables to null at all?
It is better to write a specific place and the task you are facing so it will be much easier to say how best to solve the problem.
I'm assuming you would like this:

public class Test{
    public static Test instance;
    public Long attr1 = null;
    public String attr2= null;
    public Double attr3= null;
    public Long attr4= null;
    private Test(){}
    public static synchronized Test getInstance(Boolean clear){
       if(instance==null || clear==true) instance = new Test();
       return instance;
    }
  }