StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
19164359
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2013-10-03T16:26:45.827
FavoriteCount
0
LastActivityDate
2013-10-03T16:26:45.827
LastEditDate
LastEditorUserId
0
OwnerUserId
823393
ParentId
19163889
PostTypeId
2
Score
1
ViewCount
0
LastEditorDisplayName
text
Body
<p>This one works for me - it is not generalised to <code>Collection</code> but there are utility methods that can give you an iterator-iterator across up to three levels of <code>Map</code>. I am sure you could adapt it to collections in general.</p> <pre><code>public class NestedIterator<T> implements Iterator<T> { // Outer iterator. Goes null when exhausted. Iterator<Iterator<T>> i2 = null; // Inner iterator. Goes null when exhausted. Iterator<T> i1 = null; // Next value. T next = null; // Takes a depth-2 iterator. public NestedIterator(Iterator<Iterator<T>> i2) { this.i2 = i2; // Prime the pump. if (i2 != null && i2.hasNext()) { i1 = i2.next(); } } @Override public boolean hasNext() { // Is there one waiting? if (next == null) { // No! // i1 will go null if it is exhausted. if (i1 == null) { // i1 is exhausted! Get a new one from i2. if (i2 != null && i2.hasNext()) { /// Get next. i1 = i2.next(); // Set i2 null if exhausted. if (!i2.hasNext()) { // Exhausted. i2 = null; } } else { // Exhausted. i2 = null; } } // A null i1 now will mean all is over! if (i1 != null) { if (i1.hasNext()) { // get next. next = i1.next(); // Set i1 null if exhausted. if (!i1.hasNext()) { // Exhausted. i1 = null; } } else { // Exhausted. i1 = null; } } } return next != null; } @Override public T next() { T n = next; next = null; return n; } @Override public void remove() { throw new UnsupportedOperationException("Not supported."); } // Iterating across Maps of Maps of Maps. static <K1, K2, K3, V> Iterator<Iterator<Iterator<V>>> iiiV(Map<K1, Map<K2, Map<K3, V>>> mapMapMap) { final Iterator<Map<K2, Map<K3, V>>> mmi = iV(mapMapMap); return new Iterator<Iterator<Iterator<V>>>() { @Override public boolean hasNext() { return mmi.hasNext(); } @Override public Iterator<Iterator<V>> next() { return iiV(mmi.next()); } @Override public void remove() { mmi.remove(); } }; } // Iterating across Maps of Maps. static <K1, K2, V> Iterator<Iterator<V>> iiV(Map<K1, Map<K2, V>> mapMap) { final Iterator<Map<K2, V>> mi = iV(mapMap); return new Iterator<Iterator<V>>() { @Override public boolean hasNext() { return mi.hasNext(); } @Override public Iterator<V> next() { return iV(mi.next()); } @Override public void remove() { mi.remove(); } }; } // Iterating across Map values. static <K, V> Iterator<V> iV(final Map<K, V> map) { return iV(map.entrySet().iterator()); } // Iterating across Map.Entries. static <K, V> Iterator<V> iV(final Iterator<Map.Entry<K, V>> mei) { return new Iterator<V>() { @Override public boolean hasNext() { return mei.hasNext(); } @Override public V next() { return mei.next().getValue(); } @Override public void remove() { mei.remove(); } }; } } </code></pre>
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POHow to implement iterator on nested collection in Java?
  singulars
  PostTypePostTypeId
  PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USOldCurmudgeon
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
  singulars
  PostPostId
  PO
  UserUserId
  This table or related slice is empty.
  VoteTypeVoteTypeId
  VTUpMod
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.