How should I check if two nodes have relationship with each other,in neo4j embedded database in java?

Question

I want the syntax please or a tutorial link,I have seen neo4j website but didn't find it.

Thanks.

score 12 · Accepted Answer · edited May 15 '16 at 11:43

12

Given two nodes "nodeA" and "nodeB",

gets all relationships attached to "nodeA",
```
rels = nodeA.getRelationships();
```
iterate through the collection of relationships "rels", for each relationship "rel", test whether the other end node is nodeB
```
rel.getOtherNode(nodeA).equals(nodeB)
```
if the above expression holds true for one of the relationships, then nodeA and nodeB are connected.

Here is the java API for "Node" and "Relationshiip",

http://api.neo4j.org/current/

edited May 15 '16 at 11:43

Prasad Khode

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answered Oct 20 '13 at 14:50

Lisa Li

2,562
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2

I just thought I would add, that you should consider the edge counts of `nodeA` and `nodeB` before performing this search, as you can perform it starting from either node. – Matt Way Sep 07 '14 at 02:21
2

This does not work well if you potentially have many thousands of relationships. – davedonohue Mar 09 '16 at 20:32

score 0 · Answer 2 · answered Dec 14 '16 at 21:29

private boolean sharedRelationshipExists( Node nodeA, long nodeBId)
{
    Iterator<Relationship> iterator = nodeA.getRelationships().iterator();
    while ( iterator.hasNext() )
    {
        if (iterator.next().getOtherNode( nodeA ).getId() == nodeBId) return true;
    }
    return false;
}

// in another part
boolean sharedRelationshipBetweenAB;
if ( nodeA.getDegree() < nodeB.getDegree() )
{
    sharedRelationshipBetweenAB = sharedRelationshipExists( nodeA, nodeB.getId() );
}
else
{
    sharedRelationshipBetweenAB = sharedRelationshipExists( nodeB, nodeA.getId() );
}

the boolean sharedRelationshipBetweenAB will hold your answer

How should I check if two nodes have relationship with each other,in neo4j embedded database in java?

2 Answers2