brifbraff brifbraff - 2 months ago 9
Java Question

How can I make my class iterable so I can use foreach syntax?

I have

Book
and
BookList
classes.
BookList
is something like this:

public class BookList
{
private final List<Book> bList = new ArrayList<Book>();

public int size() { return bList.size(); }

public boolean isEmpty() { ... }

public boolean contains(Book b) { ... }

public boolean add(Book b) { ... }

public boolean remove(Book b) { .. }

public void clear() { ... }

public Object get(int index) { ... }

}


In my main class I want to print titles of books with in a for each loop:

for(Book b : bList)
{
b.print();
}


Eclipse says:


Can only iterate over an array or an instance of java.lang.Iterable


How can I get this working?

Answer

You need to implement the Iterable interface, which means you need to implement the iterator() method. In your case, this might look something like this:

public class BookList implements Iterable<Book> {
    private final List<Book> bList = new ArrayList<Book>();

    @Override
    public Iterator<Book> iterator() {
        return bList.iterator();
    }

    ...
}
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