Hi all ! I trying to visualize a java embedded graph in Neo4j community.
There is my code to generate the new.db I want to visualize:
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* ownership. Neo4j licenses this file to you under
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* http://www.apache.org/licenses/LICENSE-2.0
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import java.io.File;
import java.io.IOException;
import org.neo4j.dbms.api.DatabaseManagementService;
import org.neo4j.dbms.api.DatabaseManagementServiceBuilder;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.graphdb.Transaction;
public class Embedded3 {
private static final File databaseDirectory = new File(
"/home/nicolas/neo4j-community-4.1.1/data/databases/new.db");
public String greeting;
// tag::vars[]
GraphDatabaseService graphDb;
Node firstNode;
Node secondNode;
Relationship relationship;
private DatabaseManagementService managementService;
// end::vars[]
// tag::createReltype[]
private enum RelTypes implements RelationshipType {
KNOWS
}
// end::createReltype[]
public static void main(final String[] args) throws IOException {
Embedded3 hello = new Embedded3();
hello.createDb();
// hello.removeData();
hello.shutDown();
}
void createDb() throws IOException {
// tag::startDb[]
managementService = new DatabaseManagementServiceBuilder(databaseDirectory).build();
graphDb = managementService.database("neo4j");
registerShutdownHook(managementService);
try (Transaction tx = graphDb.beginTx()) {
// Database operations go here
firstNode = tx.createNode();
firstNode.setProperty("message", "Hello, ");
secondNode = tx.createNode();
secondNode.setProperty("message", "World!");
relationship = firstNode.createRelationshipTo(secondNode, RelTypes.KNOWS);
relationship.setProperty("message", "brave Neo4j ");
// end::addData[]
greeting = ((String) firstNode.getProperty("message")) + ((String) relationship.getProperty("message"))
+ ((String) secondNode.getProperty("message"));
// tag::transaction[]
tx.commit();
}
}
void shutDown() {
System.out.println();
System.out.println("Shutting down database ...");
// tag::shutdownServer[]
managementService.shutdown();
// end::shutdownServer[]
}
// tag::shutdownHook[]
private static void registerShutdownHook(final DatabaseManagementService managementService) {
// Registers a shutdown hook for the Neo4j instance so that it
// shuts down nicely when the VM exits (even if you "Ctrl-C" the
// running application).
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
managementService.shutdown();
}
});
}
// end::shutdownHook[]
}
After, I have changed the value of dbms.default_database to dbms.default_database=new.db in neo4j.conf.
When I start neo4j, the database is well implemented:
But when I run a simple query MATCH (n) return n there is no record in the database to show.
Then I successfully created some nodes from the neo4j browser. But it's impossible to read them with my Java code, the database looks empty.
There must be an error in my code but I am really stucked right now.
Thanks for your help.
Nicolas.