Hi Sukaant,
I tried integrating my database with Java. I created a small java
application, added neo4j dependency in pom.xml.
Below is the code I wrote.
GraphDatabaseService db = new
GraphDatabaseFactory().newEmbeddedDatabase("path of my db");
ExecutionEngine engine = new ExecutionEngine(db, StringLogger.SYSTEM );
ExecutionResult result;
try ( Transaction ignored = db.beginTx() )
{
result = engine.execute( "match (n) return n" );
}
System.out.print(result);
db.shutdown();
This is throwing the below error. I tried looking for the solution, but
that was not successful. Below is the error i received.
Exception in thread "main" org.neo4j.graphdb.TransactionFailureException:
Failed to mark transaction as rollback only.
at
org.neo4j.kernel.TopLevelTransaction.markAsRollbackOnly(TopLevelTransaction.java:97)
at org.neo4j.kernel.TopLevelTransaction.failure(TopLevelTransaction.java:86)
at
org.neo4j.cypher.internal.spi.v2_1.TransactionBoundQueryContext.close(TransactionBoundQueryContext.scala:65)
at
org.neo4j.cypher.internal.compiler.v2_1.spi.DelegatingQueryContext.close(DelegatingQueryContext.scala:38)
at
org.neo4j.cypher.internal.compiler.v2_1.spi.ExceptionTranslatingQueryContext.org$neo4j$cypher$internal$compiler$v2_1$spi$ExceptionTranslatingQueryContext$$super$close(ExceptionTranslatingQueryContext.scala:34)
at
org.neo4j.cypher.internal.compiler.v2_1.spi.ExceptionTranslatingQueryContext$$anonfun$close$1.apply$mcV$sp(ExceptionTranslatingQueryContext.scala:34)
at
org.neo4j.cypher.internal.compiler.v2_1.spi.ExceptionTranslatingQueryContext$$anonfun$close$1.apply(ExceptionTranslatingQueryContext.scala:34)
at
org.neo4j.cypher.internal.compiler.v2_1.spi.ExceptionTranslatingQueryContext$$anonfun$close$1.apply(ExceptionTranslatingQueryContext.scala:34)
at
org.neo4j.cypher.internal.compiler.v2_1.spi.ExceptionTranslatingQueryContext.org$neo4j$cypher$internal$compiler$v2_1$spi$ExceptionTranslatingQueryContext$$translateException(ExceptionTranslatingQueryContext.scala:152)
at
org.neo4j.cypher.internal.compiler.v2_1.spi.ExceptionTranslatingQueryContext.close(ExceptionTranslatingQueryContext.scala:34)
at
org.neo4j.cypher.internal.compiler.v2_1.spi.DelegatingQueryContext.close(DelegatingQueryContext.scala:38)
at
org.neo4j.cypher.internal.compiler.v2_1.executionplan.ExecutionWorkflowBuilder$$anonfun$runWithQueryState$1.apply(ExecutionPlanBuilder.scala:164)
at
org.neo4j.cypher.internal.compiler.v2_1.executionplan.ExecutionWorkflowBuilder$$anonfun$runWithQueryState$1.apply(ExecutionPlanBuilder.scala:164)
at
org.neo4j.cypher.internal.compiler.v2_1.TaskCloser$$anonfun$1.apply(TaskCloser.scala:43)
at
org.neo4j.cypher.internal.compiler.v2_1.TaskCloser$$anonfun$1.apply(TaskCloser.scala:41)
at
scala.collection.TraversableLike$$anonfun$flatMap$1.apply(TraversableLike.scala:251)
at
scala.collection.TraversableLike$$anonfun$flatMap$1.apply(TraversableLike.scala:251)
at scala.collection.immutable.List.foreach(List.scala:318)
at scala.collection.TraversableLike$class.flatMap(TraversableLike.scala:251)
at scala.collection.AbstractTraversable.flatMap(Traversable.scala:105)
at
org.neo4j.cypher.internal.compiler.v2_1.TaskCloser.close(TaskCloser.scala:40)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator$$anonfun$close$1.apply$mcV$sp(ClosingIterator.scala:67)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator$$anonfun$close$1.apply(ClosingIterator.scala:67)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator$$anonfun$close$1.apply(ClosingIterator.scala:67)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator$$anonfun$translateException$1.apply(ClosingIterator.scala:72)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator.decoratedCypherException(ClosingIterator.scala:102)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator.translateException(ClosingIterator.scala:70)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator.close(ClosingIterator.scala:66)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator$$anonfun$failIfThrows$1.apply(ClosingIterator.scala:96)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator.decoratedCypherException(ClosingIterator.scala:102)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator.failIfThrows(ClosingIterator.scala:91)
at
org.neo4j.cypher.internal.compiler.v2_1.ClosingIterator.hasNext(ClosingIterator.scala:34)
at
org.neo4j.cypher.internal.compiler.v2_1.PipeExecutionResult.hasNext(PipeExecutionResult.scala:167)
at scala.collection.Iterator$class.toString(Iterator.scala:1153)
at
org.neo4j.cypher.internal.compiler.v2_1.PipeExecutionResult.toString(PipeExecutionResult.scala:35)
at java.lang.String.valueOf(String.java:2854)
at java.io.PrintStream.print(PrintStream.java:683)
at cricketFun.main(cricketFun.java:25)
Caused by: java.lang.NullPointerException
at
org.neo4j.kernel.TopLevelTransaction.markAsRollbackOnly(TopLevelTransaction.java:93)
... 37 more
Why is it failing to fetch the data? Am I doing anything wrong? Also, if I
tried running the application second time, it throws me this error.
Exception in thread "main" java.lang.RuntimeException: Error starting
org.neo4j.kernel.EmbeddedGraphDatabase,
C:\Users\sd482\Documents\Neo4j\default.graphdb
at
org.neo4j.kernel.InternalAbstractGraphDatabase.run(InternalAbstractGraphDatabase.java:362)
at
org.neo4j.kernel.EmbeddedGraphDatabase.<init>(EmbeddedGraphDatabase.java:59)
at
org.neo4j.graphdb.factory.GraphDatabaseFactory$1.newDatabase(GraphDatabaseFactory.java:90)
at
org.neo4j.graphdb.factory.GraphDatabaseBuilder.newGraphDatabase(GraphDatabaseBuilder.java:199)
at
org.neo4j.graphdb.factory.GraphDatabaseFactory.newEmbeddedDatabase(GraphDatabaseFactory.java:70)
at cricketFun.main(cricketFun.java:16)
Caused by: org.neo4j.kernel.lifecycle.LifecycleException: Component
'org.neo4j.kernel.StoreLockerLifecycleAdapter@f1bb79c' was successfully
initialized, but failed to start. Please see attached cause exception.
at
org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:513)
at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:115)
at
org.neo4j.kernel.InternalAbstractGraphDatabase.run(InternalAbstractGraphDatabase.java:339)
... 5 more
Caused by: org.neo4j.kernel.StoreLockException: Unable to obtain lock on
store lock file: C:\Users\sd482\Documents\Neo4j\default.graphdb\store_lock.
Please ensure no other process is using this database, and that the
directory is writable (required even for read-only access)
at org.neo4j.kernel.StoreLocker.checkLock(StoreLocker.java:82)
at
org.neo4j.kernel.StoreLockerLifecycleAdapter.start(StoreLockerLifecycleAdapter.java:44)
at
org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:507)
... 7 more
Caused by: java.io.IOException: Couldn't lock lock file
C:\Users\sd482\Documents\Neo4j\default.graphdb\lock because another process
already holds the lock.
at
org.neo4j.kernel.impl.nioneo.store.FileLock.getLockFileBasedFileLock(FileLock.java:120)
at
org.neo4j.kernel.impl.nioneo.store.FileLock.getOsSpecificFileLock(FileLock.java:64)
at
org.neo4j.kernel.DefaultFileSystemAbstraction.tryLock(DefaultFileSystemAbstraction.java:93)
at org.neo4j.kernel.StoreLocker.checkLock(StoreLocker.java:74)
... 9 more
I know this is due to the locking issue. Though I'm using "db.shutdown();"
in my code, it is not unlocking the database when the application is
terminated. I had to close the IDE everytime to unlock it. Please let me
know where I am making the mistake.
Sorry for the very long question, and thank you so much for your help. :)
Thanks,
Shashank
On Thursday, September 4, 2014 5:17:22 AM UTC-4, Sukaant Chaudhary wrote:
>
> Hi Shashank,
> Use the code in the following link, it is cypher-jdbc, it will help you to
> integrate with Java:
> http://docs.neo4j.org/chunked/stable/tutorials-cypher-java.html
>
> You need the following dependency:
> <dependency>
> <groupId>org.neo4j</groupId>
> <artifactId>neo4j-kernel</artifactId>
> <version>${neo4j.version}</version>
> </dependency>
>
> About Tomcat and Maven
> Tomcat is a Server whereas Maven is a build tool both are different things.
>
> Hope this will help.
> If you have any further queries please feel free to ask.
>
> -Sukaant Chaudhary
> <http://in.linkedin.com/pub/sukaant-chaudhary/33/ba8/479>
>
>
> On Thu, Sep 4, 2014 at 7:22 AM, <[email protected] <javascript:>> wrote:
>
>> Hello,
>>
>> My name is Shashank. I am currently a Masters student. I am trying to
>> explore new technologies and new to Neo4j. I have basic idea on nodes,
>> relationships and querying the database. I have developed a small database
>> in my laptop. I want to integrate it with Java and implement few algorithms
>> on the data (like apriori algorithm) for my data mining project.
>>
>> Is it a good idea to use Neo4j for data mining. If so, please let me know
>> any example that can fetch data from Neo4j server using Java. Also, I was
>> wondering whether we can use Tomcat instead of Maven.
>>
>> Your help is very much appreciated.
>>
>> Thanks,
>> Shashank
>>
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