Package org.djutils.base

Class NumberParser

  • public class NumberParser
extends Object
    NumberParser is a class that can parse a number in a strict or lenient way, and dependent on locale. It also provides help for numbers that have trailing information in the String, such as a unit. The class has been defined to use two ways of defining a parser: The first is a classical manner with a constructor that defines the settings: 
       NumberParser np = new NumberParser(true, true);
   String text = "+1.127E3 m/s";
   double d = np.parseDouble(text);
   String unit = text.substring(np.getTrailingPosition()).trim();
    or, for a simple lenient setting without trailing information: 
       double d = new NumberParser().parseDouble(text);
    Alternatively, chaining can be used: 
       double d = new NumberParser().lenient().locale(Locale.US).noTrailing().parseDouble(text);
    An instantiated NumberParser can be used multiple times, but the class is not thread-safe.

    Information on how Java handles Locales from version 11 onward can be found at https://www.oracle.com/java/technologies/javase/jdk11-suported-locales.html.

    Copyright (c) 2023-2023 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://djutils.org. The DJUTILS project is distributed under a three-clause BSD-style license, which can be found at https://djutils.org/docs/license.html.

    Author:
    Alexander Verbraeck

    • Constructor Summary

      Constructors 
      Constructor Description
      NumberParser()
      Create a new NumberParser with lenient parsing, not allowing for trailing information, and using the current Locale.
      NumberParser​(boolean trailing)
      Create a new NumberParser with lenient parsing and using the current Locale, with a setting whether or not to allow trailing information.
      NumberParser​(boolean trailing, boolean lenient)
      Create a new NumberParser, with settings for lenient parsing, whether or not to allow trailing information, and the current Locale.
      NumberParser​(boolean trailing, boolean lenient, Locale locale)
      Create a new NumberParser, with settings for lenient parsing, whether or not to allow trailing information, and the Locale to use.

    • Constructor Detail

      • NumberParser

        public NumberParser​(boolean trailing,
                    boolean lenient,
                    Locale locale)
        Create a new NumberParser, with settings for lenient parsing, whether or not to allow trailing information, and the Locale to use.
        Parameters:
        trailing - boolean; whether trailing information is accepted
        lenient - boolean; when false, strict parsing according to the Locale will be performed; when true, certain violations will be accepted
        locale - Locale; the locale to use for parsing
        Throws:
        NullPointerException - when locale is null

      • NumberParser

        public NumberParser​(boolean trailing,
                    boolean lenient)
        Create a new NumberParser, with settings for lenient parsing, whether or not to allow trailing information, and the current Locale.
        Parameters:
        trailing - boolean; whether trailing information is accepted
        lenient - boolean; when false, strict parsing according to the Locale will be performed; when true, certain violations will be accepted
        Throws:
        NullPointerException - when locale is null

      • NumberParser

        public NumberParser​(boolean trailing)
        Create a new NumberParser with lenient parsing and using the current Locale, with a setting whether or not to allow trailing information.
        Parameters:
        trailing - boolean; whether trailing information is accepted

      • NumberParser

        public NumberParser()
        Create a new NumberParser with lenient parsing, not allowing for trailing information, and using the current Locale.

    • Method Detail

      • strict

        public NumberParser strict()
        Set the parser to strict parsing. This method is included for chaining, so the following statement can be executed: 
         new NumberParser().strict().noTrailing().locale(Locale.US).parseDouble(text);
        Returns:
        the current NumberParser for chaining

      • lenient

        public NumberParser lenient()
        Set the parser to lenient parsing. This method is included for chaining, so the following statement can be executed: 
         new NumberParser().lenient().noTrailing().locale(Locale.US).parseDouble(text);
        Returns:
        the current NumberParser for chaining

      • trailing

        public NumberParser trailing()
        Set the parser to allow for trailing characters when parsing. This method is included for chaining, so the following statement can be executed: 
         new NumberParser().lenient().trailing().locale(Locale.US).parseDouble(text);
        Returns:
        the current NumberParser for chaining

      • noTrailing

        public NumberParser noTrailing()
        Set the parser to not allow for trailing characters when parsing. This method is included for chaining, so the following statement can be executed: 
         new NumberParser().lenient().noTrailing().locale(Locale.US).parseDouble(text);
        Returns:
        the current NumberParser for chaining

      • locale

        public NumberParser locale​(Locale newLocale)
        Set the locale for the parser to use. This method is included for chaining, so the following statement can be executed: 
         new NumberParser().lenient().trailing().locale(Locale.US).parseDouble(text);
        Parameters:
        newLocale - Locale; the new Locale to use
        Returns:
        the current NumberParser for chaining

      • parseDouble

        public double parseDouble​(String text)
        Parse a String and return a double value. Independent whether lenient is true or false, leading and trailing white space will be ignored in the provided text.
        Parameters:
        text - String; the text to parse
        Returns:
        double; the double number as part of the text
        Throws:
        NumberFormatException - when the text could not be parsed given the flags

      • parseFloat

        public float parseFloat​(String text)
        Parse a String and return a float value. Independent whether lenient is true or false, leading and trailing white space will be ignored in the provided text.
        Parameters:
        text - String; the text to parse
        Returns:
        float; the float number as part of the text
        Throws:
        NumberFormatException - when the text could not be parsed given the flags

      • parseInt

        public int parseInt​(String text)
        Parse a String and return an int value. Independent whether lenient is true or false, leading and trailing white space will be ignored in the provided text.
        Parameters:
        text - String; the text to parse
        Returns:
        int; the int number as part of the text
        Throws:
        NumberFormatException - when the text could not be parsed given the flags

      • parseLong

        public long parseLong​(String text)
        Parse a String and return a long value. Independent whether lenient is true or false, leading and trailing white space will be ignored in the provided text.
        Parameters:
        text - String; the text to parse
        Returns:
        long; the long number as part of the text
        Throws:
        NumberFormatException - when the text could not be parsed given the flags

      • getTrailingPosition

        public int getTrailingPosition()
        Return the position in the original String of the first character after the parsing of the number stopped. This means that the trailing String can be retrieved using: 
         NumberParser np = new NumberParser();
 double d = np.parseDouble("12.0 m/s");
 String unit = text.substring(np.getTrailingPosition()).trim();
        The substring starting with the trailing position returns leading and trailing spaces.
        Returns:
        int; the trailing position that denotes the first character after the parsing of the number stopped