Package org.json

Class JSONTokener

  • Direct Known Subclasses:
    HTTPTokener, XMLTokener
    public class JSONTokener
extends java.lang.Object
    A JSONTokener takes a source string and extracts characters and tokens from it. It is used by the JSONObject and JSONArray constructors to parse JSON source strings.
    Version:
    2014-05-03

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private long character
      current read character position on the current line.
      private long characterPreviousLine
      the number of characters read in the previous line.
      private boolean eof
      flag to indicate if the end of the input has been found.
      private long index
      current read index of the input.
      private long line
      current line of the input.
      private char previous
      previous character read from the input.
      private java.io.Reader reader
      Reader for the input.
      private boolean usePrevious
      flag to indicate that a previous character was requested.

    • Constructor Summary

      Constructors 
      Constructor Description
      JSONTokener​(java.io.InputStream inputStream)
      Construct a JSONTokener from an InputStream.
      JSONTokener​(java.io.Reader reader)
      Construct a JSONTokener from a Reader.
      JSONTokener​(java.lang.String s)
      Construct a JSONTokener from a string.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void back()
      Back up one character.
      void close()
      Closes the underlying reader, releasing any resources associated with it.
      private void decrementIndexes()
      Decrements the indexes for the back() method based on the previous character read.
      static int dehexchar​(char c)
      Get the hex value of a character (base16).
      boolean end()
      Checks if the end of the input has been reached.
      protected char getPrevious()
      Get the last character read from the input or '\0' if nothing has been read yet.
      private void incrementIndexes​(int c)
      Increments the internal indexes according to the previous character read and the character passed as the current character.
      boolean more()
      Determine if the source string still contains characters that next() can consume.
      char next()
      Get the next character in the source string.
      char next​(char c)
      Consume the next character, and check that it matches a specified character.
      java.lang.String next​(int n)
      Get the next n characters.
      char nextClean()
      Get the next char in the string, skipping whitespace.
      (package private) java.lang.Object nextSimpleValue​(char c)  
      java.lang.String nextString​(char quote)
      Return the characters up to the next close quote character.
      java.lang.String nextTo​(char delimiter)
      Get the text up but not including the specified character or the end of line, whichever comes first.
      java.lang.String nextTo​(java.lang.String delimiters)
      Get the text up but not including one of the specified delimiter characters or the end of line, whichever comes first.
      java.lang.Object nextValue()
      Get the next value.
      char skipTo​(char to)
      Skip characters until the next character is the requested character.
      JSONException syntaxError​(java.lang.String message)
      Make a JSONException to signal a syntax error.
      JSONException syntaxError​(java.lang.String message, java.lang.Throwable causedBy)
      Make a JSONException to signal a syntax error.
      java.lang.String toString()
      Make a printable string of this JSONTokener.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • character

        private long character
        current read character position on the current line.

      • eof

        private boolean eof
        flag to indicate if the end of the input has been found.

      • index

        private long index
        current read index of the input.

      • line

        private long line
        current line of the input.

      • previous

        private char previous
        previous character read from the input.

      • reader

        private final java.io.Reader reader
        Reader for the input.

      • usePrevious

        private boolean usePrevious
        flag to indicate that a previous character was requested.

      • characterPreviousLine

        private long characterPreviousLine
        the number of characters read in the previous line.

    • Constructor Detail

      • JSONTokener

        public JSONTokener​(java.io.Reader reader)
        Construct a JSONTokener from a Reader. The caller must close the Reader.
        Parameters:
        reader - A reader.

      • JSONTokener

        public JSONTokener​(java.io.InputStream inputStream)
        Construct a JSONTokener from an InputStream. The caller must close the input stream.
        Parameters:
        inputStream - The source.

      • JSONTokener

        public JSONTokener​(java.lang.String s)
        Construct a JSONTokener from a string.
        Parameters:
        s - A source string.

    • Method Detail

      • back

        public void back()
          throws JSONException
        Back up one character. This provides a sort of lookahead capability, so that you can test for a digit or letter before attempting to parse the next number or identifier.
        Throws:
        JSONException - Thrown if trying to step back more than 1 step or if already at the start of the string

      • decrementIndexes

        private void decrementIndexes()
        Decrements the indexes for the back() method based on the previous character read.

      • dehexchar

        public static int dehexchar​(char c)
        Get the hex value of a character (base16).
        Parameters:
        c - A character between '0' and '9' or between 'A' and 'F' or between 'a' and 'f'.
        Returns:
        An int between 0 and 15, or -1 if c was not a hex digit.

      • end

        public boolean end()
        Checks if the end of the input has been reached.
        Returns:
        true if at the end of the file and we didn't step back

      • more

        public boolean more()
             throws JSONException
        Determine if the source string still contains characters that next() can consume.
        Returns:
        true if not yet at the end of the source.
        Throws:
        JSONException - thrown if there is an error stepping forward or backward while checking for more data.

      • next

        public char next()
          throws JSONException
        Get the next character in the source string.
        Returns:
        The next character, or 0 if past the end of the source string.
        Throws:
        JSONException - Thrown if there is an error reading the source string.

      • getPrevious

        protected char getPrevious()
        Get the last character read from the input or '\0' if nothing has been read yet.
        Returns:
        the last character read from the input.

      • incrementIndexes

        private void incrementIndexes​(int c)
        Increments the internal indexes according to the previous character read and the character passed as the current character.
        Parameters:
        c - the current character read.

      • next

        public char next​(char c)
          throws JSONException
        Consume the next character, and check that it matches a specified character.
        Parameters:
        c - The character to match.
        Returns:
        The character.
        Throws:
        JSONException - if the character does not match.

      • next

        public java.lang.String next​(int n)
                      throws JSONException
        Get the next n characters.
        Parameters:
        n - The number of characters to take.
        Returns:
        A string of n characters.
        Throws:
        JSONException - Substring bounds error if there are not n characters remaining in the source string.

      • nextClean

        public char nextClean()
               throws JSONException
        Get the next char in the string, skipping whitespace.
        Returns:
        A character, or 0 if there are no more characters.
        Throws:
        JSONException - Thrown if there is an error reading the source string.

      • nextString

        public java.lang.String nextString​(char quote)
                            throws JSONException
        Return the characters up to the next close quote character. Backslash processing is done. The formal JSON format does not allow strings in single quotes, but an implementation is allowed to accept them.
        Parameters:
        quote - The quoting character, either " (double quote) or ' (single quote).
        Returns:
        A String.
        Throws:
        JSONException - Unterminated string.

      • nextTo

        public java.lang.String nextTo​(char delimiter)
                        throws JSONException
        Get the text up but not including the specified character or the end of line, whichever comes first.
        Parameters:
        delimiter - A delimiter character.
        Returns:
        A string.
        Throws:
        JSONException - Thrown if there is an error while searching for the delimiter

      • nextTo

        public java.lang.String nextTo​(java.lang.String delimiters)
                        throws JSONException
        Get the text up but not including one of the specified delimiter characters or the end of line, whichever comes first.
        Parameters:
        delimiters - A set of delimiter characters.
        Returns:
        A string, trimmed.
        Throws:
        JSONException - Thrown if there is an error while searching for the delimiter

      • nextValue

        public java.lang.Object nextValue()
                           throws JSONException
        Get the next value. The value can be a Boolean, Double, Integer, JSONArray, JSONObject, Long, or String, or the JSONObject.NULL object.
        Returns:
        An object.
        Throws:
        JSONException - If syntax error.

      • nextSimpleValue

        java.lang.Object nextSimpleValue​(char c)

      • skipTo

        public char skipTo​(char to)
            throws JSONException
        Skip characters until the next character is the requested character. If the requested character is not found, no characters are skipped.
        Parameters:
        to - A character to skip to.
        Returns:
        The requested character, or zero if the requested character is not found.
        Throws:
        JSONException - Thrown if there is an error while searching for the to character

      • syntaxError

        public JSONException syntaxError​(java.lang.String message)
        Make a JSONException to signal a syntax error.
        Parameters:
        message - The error message.
        Returns:
        A JSONException object, suitable for throwing

      • syntaxError

        public JSONException syntaxError​(java.lang.String message,
                                 java.lang.Throwable causedBy)
        Make a JSONException to signal a syntax error.
        Parameters:
        message - The error message.
        causedBy - The throwable that caused the error.
        Returns:
        A JSONException object, suitable for throwing

      • toString

        public java.lang.String toString()
        Make a printable string of this JSONTokener.
        Overrides:
        toString in class java.lang.Object
        Returns:
        " at {index} [character {character} line {line}]"

      • close

        public void close()
           throws java.io.IOException
        Closes the underlying reader, releasing any resources associated with it.
        Throws:
        java.io.IOException - If an I/O error occurs while closing the reader.