Simple cypher query on embedded graph DB from Java results in nullpointerexception

Question

Until now I have only interacted with neo4j through its browser and REST interface. Now I want to interact with neo4j via Java and an embedded database.

I get a null pointer exception when I attempt to run a Cypher query. The console output did not help me:

Exception in thread "main" java.lang.NullPointerException
    at org.neo4j.cypher.ExecutionEngine.execute(ExecutionEngine.scala:58)
    at org.neo4j.cypher.ExecutionEngine.execute(ExecutionEngine.scala:54)
    at org.neo4j.cypher.javacompat.ExecutionEngine.execute(ExecutionEngine.java:65)
    at neo.project1.App.main(App.java:59)

My config
- Ubuntu 14.04
- neo4j/stable,now 2.0.2 all [installed]
- java version "1.7.0_55"
- Link to .java file and pom file

BtySgtMajor · Accepted Answer · 2014-04-30 19:57:24Z

3

Try this:

ExecutionEngine engine = new ExecutionEngine(graphDb);

Sounds like your original constructor call (with the second parameter as NULL) is letting the ExecutionEngine try to use a NULL logger.

answered Apr 30, 2014 at 19:57

BtySgtMajor

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1 Comment

ahoffer Over a year ago

Thanks. That lead to a stack trace that was useful. It turns out the ExecutionResult.dumpToString must be inside of a transaction. It now works.

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