org.geotools.graph.io.standard

Class TextfileReaderWriter

Object

AbstractReaderWriter

TextfileReaderWriter

All Implemented Interfaces:

GraphReaderWriter, FileReaderWriter

public abstract class TextfileReaderWriter
extends AbstractReaderWriter
implements FileReaderWriter

An implementation of GraphReaderWriter that reads/writes graphs from/to text files. Each line of the text file represents an object to be modelled by the graph.
When performing a read, the text file is read line by line. As each line is read it is tokenized based on the delimiter property, and passed to the template method readInternal(StringTokenizer), which must be implemented by a subclass. The method returns the object that is to be represented in the graph. The returned object is then passed to an underlying GraphGenerator which creates the necessary graph components to modell the object.

When performing a write, the graph is read component by component based on set properties. If the NODES property is set, nodes will be written. If the EDGES property is set, edges will be written as well. As each component is processed, it is passed to the repspective template methods writeNode(Writer,Node) and writeEdge(Writer,Edge). The methods then write out the text representation of the component.

Author:

Justin Deoliveira, Refractions Research Inc, jdeolive@refractions.net

Field Summary

Fields

Modifier and Type	Field and Description
static String	DELIMITER line delimiter key *

Fields inherited from class AbstractReaderWriter

BUILDER, EDGES, GENERATOR, NODES

Fields inherited from interface FileReaderWriter

FILENAME

Constructor Summary

Constructors

Constructor and Description
TextfileReaderWriter()

Method Summary

Modifier and Type	Method and Description
Graph	read() Performs a read of the text file line by line.
protected abstract Object	readInternal(StringTokenizer st) Template method for returning the object represented by a line in the text file being read.
void	write(Graph g) Performs a write on the graph out to a text file.
protected void	writeEdge(Writer out, Edge e) Template method for writing the text representation of an edge to an text file.
protected void	writeNode(Writer out, Node n) Template method for writing the text representation of a node to an text file.

Methods inherited from class AbstractReaderWriter

getProperty, setProperty, setProperty

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface GraphReaderWriter

getProperty, setProperty

Field Detail

DELIMITER

public static final String DELIMITER

line delimiter key *

See Also:

Constant Field Values

Constructor Detail

TextfileReaderWriter

public TextfileReaderWriter()

Method Detail

read

public Graph read()
           throws Exception

Performs a read of the text file line by line. As each line is read the corresponding graph components represented by the line of text are created by an underlying GraphGenerator.

Specified by:

read in interface GraphReaderWriter

Returns:

The represented graph.

Throws:

Exception

See Also:

GraphGenerator#read()

write

public void write(Graph g)
           throws Exception

Performs a write on the graph out to a text file. If the NODES property is set, the nodes of the graph will be written, and if the EDGES property is set, the edges of the graph will be written.

* @see GraphGenerator#write()

Specified by:

write in interface GraphReaderWriter

Parameters:

g - The graph to be

Throws:

Exception

writeNode

protected void writeNode(Writer out,
                         Node n)

Template method for writing the text representation of a node to an text file.

Parameters:

out - The text file writer.

n - The node to write.

writeEdge

protected void writeEdge(Writer out,
                         Edge e)

Template method for writing the text representation of an edge to an text file.

Parameters:

out - The text file writer.

e - The edge to write.

readInternal

protected abstract Object readInternal(StringTokenizer st)

Template method for returning the object represented by a line in the text file being read.

Parameters:

st - The tokenized line read from text file.

Returns:

The object represented by the line of text.