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My requirements are:

Domestic Implementation:

International Implementation:

Use:

My requirements are:

Domestic Implementation:

International Implementation:

Use:

    public final class Domestic implements StudentStatus {

       private final StudentType type;
       private final Collection<String> documents;

       public Domestic() {
           this.type = StudentType.Domestic;
           this.documents = Collections.emptyList();
       }
    
       @Override
       public Collection<String> retrieveDocuments() {
           return this.documents;
       }

       @Override
       public StudentType retrieveStatus() {
           return type;
       }
   }

    public final class International implements StudentStatus {
            
       private final StudentType type;
       private Collection<String> documents;
    
       public International(Collection<String> documents) {
        
           this.type = StudentType.International;
           this.documents = Collections.unmodifiableCollection(documents);
       }

       @Override
       public Collection<String> retrieveDocuments() {
           return Collections.unmodifiableCollection(documents);
       }

       @Override
       public StudentType retrieveStatus() {
          return type;
       }
    }

    public final class Domestic implements StudentStatus {

       private final StudentType type;
       private final Collection<String> documents;

       public Domestic() {
           this.type = StudentType.Domestic;
           this.documents = unmodifiableList(new ArrayList<String>(documents);
       }
    
       @Override
       public Collection<String> retrieveDocuments() {
           return unmodifiableList(new ArrayList<String>(documents);
       }

       @Override
       public StudentType retrieveStatus() {
           return type;
       }
   }

    public final class International implements StudentStatus {
            
       private final StudentType type;
       private Collection<String> documents;
    
       public International(Collection<String> documents) {
        
           this.type = StudentType.International;
           this.documents = Collections.unmodifiableList(new ArrayList<String>(documents));
       }

       @Override
       public Collection<String> retrieveDocuments() {
           return Collections.unmodifiableList(new ArrayList<String>(documents));
       }

       @Override
       public StudentType retrieveStatus() {
          return type;
       }
    }

To recover from yesterdays disaster, I re-read the SOLID principles and refactored my code. Hopfully I did a better job than yesterday. I wanted to keep my Student class immutable, but that meant I would have to change the class everytime a new Student type was introduced, that violated the S in SOLID. Here is what I came up with.

Goal: Keep the Student immutable without violating SOLID.

To recover from yesterday's disaster, I re-read the SOLID principles and refactored my code. Hopefully I did a better job than yesterday. I wanted to keep my Student class immutable, but that meant I would have to change the class every time a new Student type was introduced, that violated the S in SOLID. Here is what I came up with.

Goal: Keep the Student immutable without violating SOLID.