将ArrayList对象分配给实例变量-Java

Question

The code snippet below is part of some code I am reading for an assignment but I cant understand the role of the copy variable in the snippet or what it does. I know its an instance of the Sample class, but why it is then assigned an ArrayList is not clear to me.

public class Sample implements Var{

   private List lst1;
   private List lst2;

   public Sample() {        
        super();
     }

    public Sample(List lst1) {      
         this();
         this.lst1 = lst1;
     }

    public List getLst1() {
        return lst1;
    }

    public void setLst1(List lst1) {
       this.lst1 = lst1;
    }

    @Override
    public Var copy(){
         Sample copy = new Sample(lst1);    
         copy.lst2 = new ArrayList(lst2);
         return copy;
    }

    @Override
    public void randomize(){

    }
}

Answer 1

In fact the error message is explicit to show that you can't iterate over the variable copy because you haven't implemented the Iterable interface which allows you to do it. If you insist to loop over it and to have functions allowing you to do so: just visit this link Java Generics - Implementing the Iterable Interface where you can for exemple (if this is what you want) iterate over the elements of the two lists of an instance lst1 and lst2