java - Neo4j 数据检索中出现空点异常

Question

我有以下代码。

GraphDatabaseFactory dbFactory = new GraphDatabaseFactory();
GraphDatabaseService db= dbFactory.newEmbeddedDatabase("C:/Users/shadid/Documents/Neo4j/DB");

ExecutionEngine execEngine = new ExecutionEngine(db, null);
ExecutionResult execResult = execEngine.execute("MATCH (mat:TheMatrix) RETURN mat");
String results = execResult.dumpToString();
System.out.println(results);

我收到一个空点异常。我尝试在 neo4j 命令行中运行该命令。所以数据确实存在。我不太确定错误在哪里。 Neo4j 中的菜鸟，所以有人可以帮助我吗

这是我遇到的错误

Exception in thread "main" java.lang.NullPointerException
at org.neo4j.cypher.internal.CypherCompiler.(CypherCompiler.scala:69)
at org.neo4j.cypher.ExecutionEngine.createCompiler(ExecutionEngine.scala:237)
at org.neo4j.cypher.ExecutionEngine.(ExecutionEngine.scala:64)
at App.Main.main(Main.java:53)

Answer 1

刚刚找到了一种更直观的方法来做同样的事情，而且它很有效!!!

try ( Transaction ignored = db.beginTx();
                  Result result = db.execute( "MATCH (n:TheIronGiant) RETURN n.`title: `" ) )
            {
            String rows ="";
            while ( result.hasNext() )
                {
                    Map<String,Object> row = result.next();

                    for ( Entry<String,Object> column : row.entrySet() )
                    {
                        rows  += column.getKey() + ": " + column.getValue() + "; ";
                    }
                    rows += "\n";
                }
            System.out.println(rows);
            }