org.locationtech.jts.io

Class WKTReader

java.lang.Object

org.locationtech.jts.io.WKTReader

public class WKTReader
extends Object

Converts a geometry in Well-Known Text format to a Geometry.

WKTReader supports extracting Geometry objects from either Readers or Strings. This allows it to function as a parser to read Geometry objects from text blocks embedded in other data formats (e.g. XML).

A WKTReader is parameterized by a GeometryFactory, to allow it to create Geometry objects of the appropriate implementation. In particular, the GeometryFactory determines the PrecisionModel and SRID that is used.

The WKTReader converts all input numbers to the precise internal representation.

As of version 1.15, JTS can read (but not write) WKT syntax which specifies coordinate dimension Z, M or ZM as modifiers (e.g. POINT Z) or in the name of the geometry type (e.g. LINESTRINGZM). If the coordinate dimension is specified it will be set in the created geometry. If the coordinate dimension is not specified, the default behaviour is to create XYZ geometry (this is backwards compatible with older JTS versions). This can be altered to create XY geometry by calling setIsOldJtsCoordinateSyntaxAllowed(boolean).

A reader can be set to ensure the input is structurally valid by calling setFixStructure(boolean). This ensures that geometry can be constructed without errors due to missing coordinates. The created geometry may still be topologically invalid.

Notes:

• Keywords are case-insensitive.
• The reader supports non-standard "LINEARRING" tags.
• The reader uses Double.parseDouble to perform the conversion of ASCII numbers to floating point. This means it supports the Java syntax for floating point literals (including scientific notation).

Syntax

The following syntax specification describes the version of Well-Known Text supported by JTS. (The specification uses a syntax language similar to that used in the C and Java language specifications.)

 WKTGeometry: one of

       WKTPoint  WKTLineString  WKTLinearRing  WKTPolygon
       WKTMultiPoint  WKTMultiLineString  WKTMultiPolygon
       WKTGeometryCollection

 WKTPoint: POINT[Dimension] ( Coordinate )

 WKTLineString: LINESTRING[Dimension] CoordinateSequence

 WKTLinearRing: LINEARRING[Dimension] CoordinateSequence

 WKTPolygon: POLYGON[Dimension] CoordinateSequenceList

 WKTMultiPoint: MULTIPOINT[Dimension] CoordinateSingletonList

 WKTMultiLineString: MULTILINESTRING[Dimension] CoordinateSequenceList

 WKTMultiPolygon:
         MULTIPOLYGON[Dimension] ( CoordinateSequenceList { , CoordinateSequenceList } )

 WKTGeometryCollection: 
         GEOMETRYCOLLECTION[Dimension]  ( WKTGeometry { , WKTGeometry } )

 CoordinateSingletonList:
         ( CoordinateSingleton { , CoordinateSingleton } )
         | EMPTY
         
 CoordinateSingleton:
         ( Coordinate )
         | EMPTY

 CoordinateSequenceList:
         ( CoordinateSequence { , CoordinateSequence } )
         | EMPTY

 CoordinateSequence:
         ( Coordinate { , Coordinate } )
         | EMPTY

 Coordinate:
         Number Number Numberopt Numberopt

 Number: A Java-style floating-point number (including NaN, with arbitrary case)

 Dimension:
         Z| Z|M| M|ZM| ZM

 

Version:

1.7

See Also:

WKTWriter

Constructor Summary

Constructors

Constructor and Description
WKTReader() Creates a reader that creates objects using the default GeometryFactory.
WKTReader(GeometryFactory geometryFactory) Creates a reader that creates objects using the given GeometryFactory.

Method Summary

Modifier and Type	Method and Description
Geometry	read(Reader reader) Reads a Well-Known Text representation of a Geometry from a Reader.
Geometry	read(String wellKnownText) Reads a Well-Known Text representation of a Geometry from a String.
void	setFixStructure(boolean isFixStructure) Sets a flag indicating that the structure of input geometry should be fixed so that the geometry can be constructed without error.
void	setIsOldJtsCoordinateSyntaxAllowed(boolean value) Sets a flag indicating, that coordinates may have 3 ordinate values even though no Z or M ordinate indicator is present.
void	setIsOldJtsMultiPointSyntaxAllowed(boolean value) Sets a flag indicating, that point coordinates in a MultiPoint geometry must not be enclosed in paren.

Methods inherited from class java.lang.Object

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

Constructor Detail

WKTReader

public WKTReader()

Creates a reader that creates objects using the default GeometryFactory.

WKTReader

public WKTReader(GeometryFactory geometryFactory)

Creates a reader that creates objects using the given GeometryFactory.

Parameters:

geometryFactory - the factory used to create Geometrys.

Method Detail

setIsOldJtsCoordinateSyntaxAllowed

public void setIsOldJtsCoordinateSyntaxAllowed(boolean value)

Sets a flag indicating, that coordinates may have 3 ordinate values even though no Z or M ordinate indicator is present. The default value is ALLOW_OLD_JTS_COORDINATE_SYNTAX.

Parameters:

value - a boolean value

setIsOldJtsMultiPointSyntaxAllowed

public void setIsOldJtsMultiPointSyntaxAllowed(boolean value)

Sets a flag indicating, that point coordinates in a MultiPoint geometry must not be enclosed in paren. The default value is ALLOW_OLD_JTS_MULTIPOINT_SYNTAX

Parameters:

value - a boolean value

setFixStructure

public void setFixStructure(boolean isFixStructure)

Sets a flag indicating that the structure of input geometry should be fixed so that the geometry can be constructed without error. This involves adding coordinates if the input coordinate sequence is shorter than required.

Parameters:

isFixStructure - true if the input structure should be fixed

See Also:

LinearRing.MINIMUM_VALID_SIZE

read

public Geometry read(String wellKnownText)
              throws ParseException

Reads a Well-Known Text representation of a Geometry from a String.

Parameters:

wellKnownText - one or more <Geometry Tagged Text> strings (see the OpenGIS Simple Features Specification) separated by whitespace

Returns:

a Geometry specified by wellKnownText

Throws:

ParseException - if a parsing problem occurs

read

public Geometry read(Reader reader)
              throws ParseException

Reads a Well-Known Text representation of a Geometry from a Reader.

Parameters:

reader - a Reader which will return a <Geometry Tagged Text> string (see the OpenGIS Simple Features Specification)

Returns:

a Geometry read from reader

Throws:

ParseException - if a parsing problem occurs