Package 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.

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.)

As of version 1.15, JTS can read (but not write) WKT Strings including Z, M or ZM in the name of the geometry type (ex. POINT Z, LINESTRINGZM). Note that it only makes the reader more flexible, but JTS could already read 3D coordinates from WKT String and still can't read 4D coordinates. 

 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

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

 Dimension:
         Z| Z|M| M|ZM| ZM
Version:
1.7
See Also:

  • Field Details

  • Constructor Details

    • 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 Details

    • 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

    • getCoordinates

      private Coordinate[] getCoordinates() throws IOException, ParseException
      Returns the next array of Coordinates in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next element returned by the stream should be L_PAREN (the beginning of "(x1 y1, x2 y2, ..., xn yn)") or EMPTY.
      Returns:
      the next array of Coordinates in the stream, or an empty array if EMPTY is the next element returned by the stream.
      Throws:
      IOException - if an I/O error occurs
      ParseException - if an unexpected token was encountered

    • getCoordinatesNoLeftParen

      private Coordinate[] getCoordinatesNoLeftParen() throws IOException, ParseException
      Throws:
      IOException
      ParseException

    • getPreciseCoordinate

      private Coordinate getPreciseCoordinate() throws IOException, ParseException
      Throws:
      IOException
      ParseException

    • isNumberNext

      private boolean isNumberNext() throws IOException
      Throws:
      IOException

    • getNextNumber

      private double getNextNumber() throws IOException, ParseException
      Parses the next number in the stream. Numbers with exponents are handled. NaN values are handled correctly, and the case of the "NaN" symbol is not significant.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be a number.
      Returns:
      the next number in the stream
      Throws:
      ParseException - if the next token is not a valid number
      IOException - if an I/O error occurs

    • getNextEmptyOrOpener

      private String getNextEmptyOrOpener() throws IOException, ParseException
      Returns the next EMPTY or L_PAREN in the stream as uppercase text.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be EMPTY or L_PAREN.
      Returns:
      the next EMPTY or L_PAREN in the stream as uppercase text.
      Throws:
      ParseException - if the next token is not EMPTY or L_PAREN
      IOException - if an I/O error occurs

    • getNextCloserOrComma

      private String getNextCloserOrComma() throws IOException, ParseException
      Returns the next R_PAREN or COMMA in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be R_PAREN or COMMA.
      Returns:
      the next R_PAREN or COMMA in the stream
      Throws:
      ParseException - if the next token is not R_PAREN or COMMA
      IOException - if an I/O error occurs

    • getNextCloser

      private String getNextCloser() throws IOException, ParseException
      Returns the next R_PAREN in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be R_PAREN.
      Returns:
      the next R_PAREN in the stream
      Throws:
      ParseException - if the next token is not R_PAREN
      IOException - if an I/O error occurs

    • getNextWord

      private String getNextWord() throws IOException, ParseException
      Returns the next word in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be a word.
      Returns:
      the next word in the stream as uppercase text
      Throws:
      ParseException - if the next token is not a word
      IOException - if an I/O error occurs

    • lookaheadWord

      private String lookaheadWord() throws IOException, ParseException
      Returns the next word in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be a word.
      Returns:
      the next word in the stream as uppercase text
      Throws:
      ParseException - if the next token is not a word
      IOException - if an I/O error occurs

    • parseErrorExpected

      private void parseErrorExpected(String expected) throws ParseException
      Throws a formatted ParseException reporting that the current token was unexpected.
      Parameters:
      expected - a description of what was expected
      Throws:
      ParseException
      AssertionFailedException - if an invalid token is encountered

    • parseErrorWithLine

      private void parseErrorWithLine(String msg) throws ParseException
      Throws:
      ParseException

    • tokenString

      private String tokenString()
      Gets a description of the current token
      Returns:
      a description of the current token

    • readGeometryTaggedText

      private Geometry readGeometryTaggedText() throws IOException, ParseException
      Creates a Geometry using the next token in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <Geometry Tagged Text>.
      Returns:
      a Geometry specified by the next token in the stream
      Throws:
      ParseException - if the coordinates used to create a Polygon shell and holes do not form closed linestrings, or if an unexpected token was encountered
      IOException - if an I/O error occurs

    • readPointText

      private Point readPointText() throws IOException, ParseException
      Creates a Point using the next token in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <Point Text>.
      Returns:
      a Point specified by the next token in the stream
      Throws:
      IOException - if an I/O error occurs
      ParseException - if an unexpected token was encountered

    • readLineStringText

      private LineString readLineStringText() throws IOException, ParseException
      Creates a LineString using the next token in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <LineString Text>.
      Returns:
      a LineString specified by the next token in the stream
      Throws:
      IOException - if an I/O error occurs
      ParseException - if an unexpected token was encountered

    • readLinearRingText

      private LinearRing readLinearRingText() throws IOException, ParseException
      Creates a LinearRing using the next token in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <LineString Text>.
      Returns:
      a LinearRing specified by the next token in the stream
      Throws:
      IOException - if an I/O error occurs
      ParseException - if the coordinates used to create the LinearRing do not form a closed linestring, or if an unexpected token was encountered

    • readMultiPointText

      private MultiPoint readMultiPointText() throws IOException, ParseException
      Creates a MultiPoint using the next tokens in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <MultiPoint Text>.
      Returns:
      a MultiPoint specified by the next token in the stream
      Throws:
      IOException - if an I/O error occurs
      ParseException - if an unexpected token was encountered

    • toPoints

      private Point[] toPoints(Coordinate[] coordinates)
      Creates an array of Points having the given Coordinate s.
      Parameters:
      coordinates - the Coordinates with which to create the Points
      Returns:
      Points created using this WKTReader s GeometryFactory

    • readPolygonText

      private Polygon readPolygonText() throws IOException, ParseException
      Creates a Polygon using the next token in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <Polygon Text>.
      Returns:
      a Polygon specified by the next token in the stream
      Throws:
      ParseException - if the coordinates used to create the Polygon shell and holes do not form closed linestrings, or if an unexpected token was encountered.
      IOException - if an I/O error occurs

    • readMultiLineStringText

      private MultiLineString readMultiLineStringText() throws IOException, ParseException
      Creates a MultiLineString using the next token in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <MultiLineString Text>.
      Returns:
      a MultiLineString specified by the next token in the stream
      Throws:
      IOException - if an I/O error occurs
      ParseException - if an unexpected token was encountered

    • readMultiPolygonText

      private MultiPolygon readMultiPolygonText() throws IOException, ParseException
      Creates a MultiPolygon using the next token in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <MultiPolygon Text>.
      Returns:
      a MultiPolygon specified by the next token in the stream, or if if the coordinates used to create the Polygon shells and holes do not form closed linestrings.
      Throws:
      IOException - if an I/O error occurs
      ParseException - if an unexpected token was encountered

    • readGeometryCollectionText

      private GeometryCollection readGeometryCollectionText() throws IOException, ParseException
      Creates a GeometryCollection using the next token in the stream.
      Parameters:
      tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <GeometryCollection Text>.
      Returns:
      a GeometryCollection specified by the next token in the stream
      Throws:
      ParseException - if the coordinates used to create a Polygon shell and holes do not form closed linestrings, or if an unexpected token was encountered
      IOException - if an I/O error occurs