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## org.neo4j.graphdb
Interface Node

All Superinterfaces:
  PropertyContainer

    public interface Node

extends PropertyContainer

A node in the graph with properties and relationships to other entities. Along with `relationships`, nodes are the core building blocks of the Neo4j data representation model. Nodes are created by invoking the `GraphDatabaseService.createNode()` method.

Node has three major groups of operations: operations that deal with relationships, operations that deal with properties (see `PropertyContainer`) and operations that create `traversers`.

The relationship operations provide a number of overloaded accessors (such as `getRelationships(...)` with "filters" for type, direction, etc), as well as the factory method `createRelationshipTo(...)` that connects two nodes with a relationship. It also includes the convenience method `getSingleRelationship(...)` for accessing the commonly occurring one-to-zero-or-one association.

The property operations give access to the key-value property pairs. Property keys are always strings. Valid property value types are all the Java primitives (`int`, `byte`, `float`, etc), `java.lang.String`s and arrays of primitives and Strings.

Please note that Neo4j does NOT accept arbitrary objects as property values. `setProperty()` takes a `java.lang.Object` only to avoid an explosion of overloaded `setProperty()` methods. For further documentation see `PropertyContainer`.

The traversal factory methods instantiate a `traverser` that starts traversing from this node.

A node's id is unique, but may not be unique over time since neo4j reuses deleted ids. See wiki.neo4j.org/content/Id_Reuse.

Method Summary
`Relationship` | `createRelationshipTo(Node otherNode, RelationshipType type)` Creates a relationship between this node and another node.
`void` | `delete()` Deletes this node if it has no relationships attached to it.
`long` | `getId()` Returns the unique id of this node.
`Iterable<Relationship>` | `getRelationships()` Returns all the relationships attached to this node.
`Iterable<Relationship>` | `getRelationships(Direction dir)` Returns all `OUTGOING` or `INCOMING` relationships from this node.
`Iterable<Relationship>` | `getRelationships(RelationshipType... types)` Returns all the relationships of any of the types in `types` that are attached to this node, regardless of direction.
`Iterable<Relationship>` | `getRelationships(RelationshipType type, Direction dir)` Returns all relationships with the given type and direction that are attached to this node.
`Relationship` | `getSingleRelationship(RelationshipType type, Direction dir)` Returns the only relationship of a given type and direction that is attached to this node, or `null`.
`boolean` | `hasRelationship()` Returns `true` if there are any relationships attached to this node, `false` otherwise.
`boolean` | `hasRelationship(Direction dir)` Returns `true` if there are any relationships in the given direction attached to this node, `false` otherwise.
`boolean` | `hasRelationship(RelationshipType... types)` Returns `true` if there are any relationships of any of the types in `types` attached to this node (regardless of direction), `false` otherwise.
`boolean` | `hasRelationship(RelationshipType type, Direction dir)` Returns `true` if there are any relationships of the given relationship type and direction attached to this node, `false` otherwise.
`Traverser` | `traverse(Traverser.Order traversalOrder, StopEvaluator stopEvaluator, ReturnableEvaluator returnableEvaluator, Object... relationshipTypesAndDirections)` Instantiates a traverser that will start at this node and traverse according to the given order and evaluators along the specified relationship type and direction pairs.
`Traverser` | `traverse(Traverser.Order traversalOrder, StopEvaluator stopEvaluator, ReturnableEvaluator returnableEvaluator, RelationshipType relationshipType, Direction direction)` Instantiates a traverser that will start at this node and traverse according to the given order and evaluators along the specified relationship type and direction.
`Traverser` | `traverse(Traverser.Order traversalOrder, StopEvaluator stopEvaluator, ReturnableEvaluator returnableEvaluator, RelationshipType firstRelationshipType, Direction firstDirection, RelationshipType secondRelationshipType, Direction secondDirection)` Instantiates a traverser that will start at this node and traverse according to the given order and evaluators along the two specified relationship type and direction pairs.

Methods inherited from interface org.neo4j.graphdb.PropertyContainer
`getGraphDatabase, getProperty, getProperty, getPropertyKeys, getPropertyValues, hasProperty, removeProperty, setProperty`

Method Detail

### getId

    long getId()

  Returns the unique id of this node. Ids are garbage collected over time so they are only guaranteed to be unique during a specific time span: if the node is deleted, it's likely that a new node at some point will get the old id. Note: this makes node ids brittle as public APIs.

  Returns:
    the id of this node

### delete

    void delete()

  Deletes this node if it has no relationships attached to it. If `delete()` is invoked on a node with relationships, an unchecked exception will be raised when the transaction is committed. Invoking any methods on this node after `delete()` has returned is invalid and will lead to unspecified behavior.

  Throws:
    `RuntimeException` - if this node has relationships attached to it

### getRelationships

    Iterable<Relationship> getRelationships()

  Returns all the relationships attached to this node. If no relationships are attached to this node, an empty iterable will be returned.

  Returns:
    all relationships attached to this node

### hasRelationship

    boolean hasRelationship()

  Returns `true` if there are any relationships attached to this node, `false` otherwise.

  Returns:
    `true` if there are any relationships attached to this node, `false` otherwise

### getRelationships

    Iterable<Relationship> getRelationships(RelationshipType... types)

  Returns all the relationships of any of the types in `types` that are attached to this node, regardless of direction. If no relationships of the given types are attached to this node, an empty iterable will be returned.

  Parameters:
    `types` - the given relationship type(s)
  Returns:
    all relationships of the given type(s) that are attached to this node

### hasRelationship

    boolean hasRelationship(RelationshipType... types)

  Returns `true` if there are any relationships of any of the types in `types` attached to this node (regardless of direction), `false` otherwise.

  Parameters:
    `types` - the given relationship type(s)
  Returns:
    `true` if there are any relationships of any of the types in `types` attached to this node, `false` otherwise

### getRelationships

    Iterable<Relationship> getRelationships(Direction dir)

  Returns all `OUTGOING` or `INCOMING` relationships from this node. If there are no relationships with the given direction attached to this node, an empty iterable will be returned. If `BOTH` is passed in as a direction, relationships of both directions are returned (effectively turning this into `getRelationships()`).

  Parameters:
    `dir` - the given direction, where `Direction.OUTGOING` means all relationships that have this node as `start node` and `Direction.INCOMING` means all relationships that have this node as `end node`
  Returns:
    all relationships with the given direction that are attached to this node

### hasRelationship

    boolean hasRelationship(Direction dir)

  Returns `true` if there are any relationships in the given direction attached to this node, `false` otherwise. If `BOTH` is passed in as a direction, relationships of both directions are matched (effectively turning this into `hasRelationships()`).

  Parameters:
    `dir` - the given direction, where `Direction.OUTGOING` means all relationships that have this node as `start node` and `Direction.INCOMING` means all relationships that have this node as `end node`
  Returns:
    `true` if there are any relationships in the given direction attached to this node, `false` otherwise

### getRelationships

    Iterable<Relationship> getRelationships(RelationshipType type,
                                            Direction dir)

  Returns all relationships with the given type and direction that are attached to this node. If there are no matching relationships, an empty iterable will be returned.

  Parameters:
    `type` - the given type
    `dir` - the given direction, where `Direction.OUTGOING` means all relationships that have this node as `start node` and `Direction.INCOMING` means all relationships that have this node as `end node`
  Returns:
    all relationships attached to this node that match the given type and direction

### hasRelationship

    boolean hasRelationship(RelationshipType type,
                            Direction dir)

  Returns `true` if there are any relationships of the given relationship type and direction attached to this node, `false` otherwise.

  Parameters:
    `type` - the given type
    `dir` - the given direction, where `Direction.OUTGOING` means all relationships that have this node as `start node` and `Direction.INCOMING` means all relationships that have this node as `end node`
  Returns:
    `true` if there are any relationships of the given relationship type and direction attached to this node, `false` otherwise

### getSingleRelationship

    Relationship getSingleRelationship(RelationshipType type,
                                       Direction dir)

  Returns the only relationship of a given type and direction that is attached to this node, or `null`. This is a convenience method that is used in the commonly occuring situation where a node has exactly zero or one relationships of a given type and direction to another node. Typically this invariant is maintained by the rest of the code: if at any time more than one such relationships exist, it is a fatal error that should generate an unchecked exception. This method reflects that semantics and returns either:

  1. `null` if there are zero relationships of the given type and direction,
  2. the relationship if there's exactly one, or
  3. throws an unchecked exception in all other cases.

  This method should be used only in situations with an invariant as described above. In those situations, a "state-checking" method (e.g. `hasSingleRelationship(...)`) is not required, because this method behaves correctly "out of the box."

  Parameters:
    `type` - the type of the wanted relationship
    `dir` - the direction of the wanted relationship (where `Direction.OUTGOING` means a relationship that has this node as `start node` and `Direction.INCOMING` means a relationship that has this node as `end node`) or `Direction.BOTH` if direction is irrelevant
  Returns:
    the single relationship matching the given type and direction if exactly one such relationship exists, or `null` if exactly zero such relationships exists
  Throws:
    `RuntimeException` - if more than one relationship matches the given type and direction

### createRelationshipTo

    Relationship createRelationshipTo(Node otherNode,
                                      RelationshipType type)

  Creates a relationship between this node and another node. The relationship is of type `type`. It starts at this node and ends at `otherNode`.

  Neo4j doesn't support self-relationships, i.e. relationships where the start node and end node are the same. If `otherNode` is the same as this node then an exception will be thrown.

  A relationship is equally well traversed in both directions so there's no need to create another relationship in the opposite direction (in regards to traversal or performance).

  Parameters:
    `otherNode` - the end node of the new relationship
    `type` - the type of the new relationship
  Returns:
    the newly created relationship

### traverse

    Traverser traverse(Traverser.Order traversalOrder,
                       StopEvaluator stopEvaluator,
                       ReturnableEvaluator returnableEvaluator,
                       RelationshipType relationshipType,
                       Direction direction)

  Instantiates a traverser that will start at this node and traverse according to the given order and evaluators along the specified relationship type and direction. If the traverser should traverse more than one `RelationshipType`/`Direction` pair, use one of the overloaded variants of this method. The created traverser will iterate over each node that can be reached from this node by the spanning tree formed by the given relationship types (with direction) exactly once. For more information about traversal, see the `Traverser` documentation.

  Parameters:
    `traversalOrder` - the traversal order
    `stopEvaluator` - an evaluator instructing the new traverser about when to stop traversing, either a predefined evaluator such as `StopEvaluator.END_OF_GRAPH` or a custom-written evaluator
    `returnableEvaluator` - an evaluator instructing the new traverser about whether a specific node should be returned from the traversal, either a predefined evaluator such as `ReturnableEvaluator.ALL` or a customer-written evaluator
    `relationshipType` - the relationship type that the traverser will traverse along
    `direction` - the direction in which the relationships of type `relationshipType` will be traversed
  Returns:
    a new traverser, configured as above

### traverse

    Traverser traverse(Traverser.Order traversalOrder,
                       StopEvaluator stopEvaluator,
                       ReturnableEvaluator returnableEvaluator,
                       RelationshipType firstRelationshipType,
                       Direction firstDirection,
                       RelationshipType secondRelationshipType,
                       Direction secondDirection)

  Instantiates a traverser that will start at this node and traverse according to the given order and evaluators along the two specified relationship type and direction pairs. If the traverser should traverse more than two `RelationshipType`/`Direction` pairs, use the overloaded `varargs variant` of this method. The created traverser will iterate over each node that can be reached from this node by the spanning tree formed by the given relationship types (with direction) exactly once. For more information about traversal, see the `Traverser` documentation.

  Parameters:
    `traversalOrder` - the traversal order
    `stopEvaluator` - an evaluator instructing the new traverser about when to stop traversing, either a predefined evaluator such as `StopEvaluator.END_OF_GRAPH` or a custom-written evaluator
    `returnableEvaluator` - an evaluator instructing the new traverser about whether a specific node should be returned from the traversal, either a predefined evaluator such as `ReturnableEvaluator.ALL` or a customer-written evaluator
    `firstRelationshipType` - the first of the two relationship types that the traverser will traverse along
    `firstDirection` - the direction in which the first relationship type will be traversed
    `secondRelationshipType` - the second of the two relationship types that the traverser will traverse along
    `secondDirection` - the direction that the second relationship type will be traversed
  Returns:
    a new traverser, configured as above

### traverse

    Traverser traverse(Traverser.Order traversalOrder,
                       StopEvaluator stopEvaluator,
                       ReturnableEvaluator returnableEvaluator,
                       Object... relationshipTypesAndDirections)

  Instantiates a traverser that will start at this node and traverse according to the given order and evaluators along the specified relationship type and direction pairs. Unlike the overloaded variants of this method, the relationship types and directions are passed in as a "varargs" variable-length argument which means that an arbitrary set of relationship type and direction pairs can be specified. The variable-length argument list should be every other relationship type and direction, starting with relationship type, e.g:

  `node.traverse( BREADTH_FIRST, stopEval, returnableEval, MyRels.REL1, Direction.OUTGOING, MyRels.REL2, Direction.OUTGOING, MyRels.REL3, Direction.BOTH, MyRels.REL4, Direction.INCOMING );`

  Unfortunately, the compiler cannot enforce this so an unchecked exception is raised if the variable-length argument has a different constitution.

  The created traverser will iterate over each node that can be reached from this node by the spanning tree formed by the given relationship types (with direction) exactly once. For more information about traversal, see the `Traverser` documentation.

  Parameters:
    `traversalOrder` - the traversal order
    `stopEvaluator` - an evaluator instructing the new traverser about when to stop traversing, either a predefined evaluator such as `StopEvaluator.END_OF_GRAPH` or a custom-written evaluator
    `returnableEvaluator` - an evaluator instructing the new traverser about whether a specific node should be returned from the traversal, either a predefined evaluator such as `ReturnableEvaluator.ALL` or a customer-written evaluator
    `relationshipTypesAndDirections` - a variable-length list of relationship types and their directions, where the first argument is a relationship type, the second argument the first type's direction, the third a relationship type, the fourth its direction, etc
  Returns:
    a new traverser, configured as above
  Throws:
    `RuntimeException` - if the variable-length relationship type / direction list is not as described above

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Copyright © 2011 The Neo4j Graph Database Project. All Rights Reserved.