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## com.vividsolutions.jts.planargraph
Class PlanarGraph

    java.lang.Object
      com.vividsolutions.jts.planargraph.PlanarGraph

Direct Known Subclasses:
  LineMergeGraph

    public abstract class PlanarGraph

extends java.lang.Object

Represents a directed graph which is embeddable in a planar surface.

This class and the other classes in this package serve as a framework for building planar graphs for specific algorithms. This class must be subclassed to expose appropriate methods to construct the graph. This allows controlling the types of graph components (`DirectedEdge`s, `Edge`s and `Node`s) which can be added to the graph. An application which uses the graph framework will almost always provide subclasses for one or more graph components, which hold application-specific data and graph algorithms.

Version:
  1.7

Field Summary
`protected java.util.Set` | `dirEdges`
`protected java.util.Set` | `edges`
`protected NodeMap` | `nodeMap`

Constructor Summary
`PlanarGraph()` Constructs a empty graph.

Method Summary
`protected void` | `add(DirectedEdge dirEdge)` Adds the Edge to this PlanarGraph; only subclasses can add DirectedEdges, to ensure the edges added are of the right class.
`protected void` | `add(Edge edge)` Adds the Edge and its DirectedEdges with this PlanarGraph.
`protected void` | `add(Node node)` Adds a node to the map, replacing any that is already at that location.
`boolean` | `contains(DirectedEdge de)` Tests whether this graph contains the given `DirectedEdge`
`boolean` | `contains(Edge e)` Tests whether this graph contains the given `Edge`
`java.util.Iterator` | `dirEdgeIterator()` Returns an Iterator over the DirectedEdges in this PlanarGraph, in the order in which they were added.
`java.util.Iterator` | `edgeIterator()` Returns an Iterator over the Edges in this PlanarGraph, in the order in which they were added.
`Node` | `findNode(Coordinate pt)` Returns the `Node` at the given location, or null if no `Node` was there.
`java.util.List` | `findNodesOfDegree(int degree)` Returns all Nodes with the given number of Edges around it.
`java.util.Collection` | `getEdges()` Returns the Edges that have been added to this PlanarGraph
`java.util.Collection` | `getNodes()`
`java.util.Iterator` | `nodeIterator()` Returns an Iterator over the Nodes in this PlanarGraph.
`void` | `remove(DirectedEdge de)` Removes a `DirectedEdge` from its from-`Node` and from this graph.
`void` | `remove(Edge edge)` Removes an `Edge` and its associated `DirectedEdge`s from their from-Nodes and from the graph.
`void` | `remove(Node node)` Removes a node from the graph, along with any associated DirectedEdges and Edges.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### edges

    protected java.util.Set edges

### dirEdges

    protected java.util.Set dirEdges

### nodeMap

    protected NodeMap nodeMap

Constructor Detail

### PlanarGraph

    public PlanarGraph()

  Constructs a empty graph.

Method Detail

### findNode

    public Node findNode(Coordinate pt)

  Returns the `Node` at the given location, or null if no `Node` was there.

  Parameters:
    `pt` - the location to query
  Returns:
    the node found or `null` if this graph contains no node at the location

### add

    protected void add(Node node)

  Adds a node to the map, replacing any that is already at that location. Only subclasses can add Nodes, to ensure Nodes are of the right type.

  Parameters:
    `node` - the node to add

### add

    protected void add(Edge edge)

  Adds the Edge and its DirectedEdges with this PlanarGraph. Assumes that the Edge has already been created with its associated DirectEdges. Only subclasses can add Edges, to ensure the edges added are of the right class.

### add

    protected void add(DirectedEdge dirEdge)

  Adds the Edge to this PlanarGraph; only subclasses can add DirectedEdges, to ensure the edges added are of the right class.

### nodeIterator

    public java.util.Iterator nodeIterator()

  Returns an Iterator over the Nodes in this PlanarGraph.

### contains

    public boolean contains(Edge e)

  Tests whether this graph contains the given `Edge`

  Parameters:
    `e` - the edge to query
  Returns:
    `true` if the graph contains the edge

### contains

    public boolean contains(DirectedEdge de)

  Tests whether this graph contains the given `DirectedEdge`

  Parameters:
    `de` - the directed edge to query
  Returns:
    `true` if the graph contains the directed edge

### getNodes

    public java.util.Collection getNodes()

### dirEdgeIterator

    public java.util.Iterator dirEdgeIterator()

  Returns an Iterator over the DirectedEdges in this PlanarGraph, in the order in which they were added.

  See Also:
    `add(Edge)`, `add(DirectedEdge)`

### edgeIterator

    public java.util.Iterator edgeIterator()

  Returns an Iterator over the Edges in this PlanarGraph, in the order in which they were added.

  See Also:
    `add(Edge)`

### getEdges

    public java.util.Collection getEdges()

  Returns the Edges that have been added to this PlanarGraph

  See Also:
    `add(Edge)`

### remove

    public void remove(Edge edge)

  Removes an `Edge` and its associated `DirectedEdge`s from their from-Nodes and from the graph. Note: This method does not remove the `Node`s associated with the `Edge`, even if the removal of the `Edge` reduces the degree of a `Node` to zero.

### remove

    public void remove(DirectedEdge de)

  Removes a `DirectedEdge` from its from-`Node` and from this graph. This method does not remove the `Node`s associated with the DirectedEdge, even if the removal of the DirectedEdge reduces the degree of a Node to zero.

### remove

    public void remove(Node node)

  Removes a node from the graph, along with any associated DirectedEdges and Edges.

### findNodesOfDegree

    public java.util.List findNodesOfDegree(int degree)

  Returns all Nodes with the given number of Edges around it.

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