Package org.json

Class JSONTokener

java.lang.Object

org.json.JSONTokener

public class JSONTokener
extends Object

Parses a JSON (RFC 4627) encoded string into the corresponding object. Most clients of this class will use only need the constructor and nextValue() method. Example usage:

 String json = "{"
         + "  \"query\": \"Pizza\", "
         + "  \"locations\": [ 94043, 90210 ] "
         + "}";

 JSONObject object = (JSONObject) new JSONTokener(json).nextValue();
 String query = object.getString("query");
 JSONArray locations = object.getJSONArray("locations");

For best interoperability and performance use JSON that complies with RFC 4627, such as that generated by JSONStringer. For legacy reasons this parser is lenient, so a successful parse does not indicate that the input string was valid JSON. All of the following syntax errors will be ignored:

• End of line comments starting with // or # and ending with a newline character.
• C-style comments starting with /* and ending with */. Such comments may not be nested.
• Strings that are unquoted or 'single quoted'.
• Hexadecimal integers prefixed with 0x or 0X.
• Octal integers prefixed with 0.
• Array elements separated by ;.
• Unnecessary array separators. These are interpreted as if null was the omitted value.
• Key-value pairs separated by = or =>.
• Key-value pairs separated by ;.

Each tokener may be used to parse a single JSON string. Instances of this class are not thread safe. Although this class is nonfinal, it was not designed for inheritance and should not be subclassed. In particular, self-use by overrideable methods is not specified. See Effective Java Item 17, "Design and Document or inheritance or else prohibit it" for further information.

Field Summary

Fields

Modifier and Type	Field	Description
private final String	in	The input JSON.
private int	pos	The index of the next character to be returned by next().

Constructor Summary

Constructors

Constructor	Description
JSONTokener(String in)

Method Summary

Modifier and Type	Method	Description
void	back()	Unreads the most recent character of input.
static int	dehexchar(char hex)	Returns the integer [0..15] value for the given hex character, or -1 for non-hex input.
boolean	more()	Returns true until the input has been exhausted.
char	next()	Returns the next available character, or the null character '\0' if all input has been exhausted.
char	next(char c)	Returns the next available character if it equals c.
String	next(int length)	Returns the next length characters of the input.
char	nextClean()	Returns the next character that is not whitespace and does not belong to a comment.
private int	nextCleanInternal()
String	nextString(char quote)	Returns the string up to but not including quote, unescaping any character escape sequences encountered along the way.
String	nextTo(char excluded)	Equivalent to nextTo(String.valueOf(excluded)).
String	nextTo(String excluded)	Returns the trimmed string holding the characters up to but not including the first of: any character in excluded a newline character '\n' a carriage return '\r'
private String	nextToInternal(String excluded)	Returns the string up to but not including any of the given characters or a newline character.
Object	nextValue()	Returns the next value from the input.
private JSONArray	readArray()	Reads a sequence of values and the trailing closing brace ']' of an array.
private char	readEscapeCharacter()	Unescapes the character identified by the character or characters that immediately follow a backslash.
private Object	readLiteral()	Reads a null, boolean, numeric or unquoted string literal value.
private JSONObject	readObject()	Reads a sequence of key/value pairs and the trailing closing brace '}' of an object.
void	skipPast(String thru)	Advances past all input up to and including the next occurrence of thru.
char	skipTo(char to)	Advances past all input up to but not including the next occurrence of to.
private void	skipToEndOfLine()	Advances the position until after the next newline character.
JSONException	syntaxError(String message)	Returns an exception containing the given message plus the current position and the entire input string.
String	toString()	Returns the current position and the entire input string.

Methods inherited from class java.lang.Object

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

Field Details

in

private final String in

The input JSON.

pos

private int pos

The index of the next character to be returned by next(). When the input is exhausted, this equals the input's length.

Constructor Details

JSONTokener

public JSONTokener(String in)

Parameters:

in - JSON encoded string. Null is not permitted and will yield a tokener that throws NullPointerExceptions when methods are called.

Method Details

nextValue

public Object nextValue()
                 throws JSONException

Returns the next value from the input.

Returns:

a JSONObject, JSONArray, String, Boolean, Integer, Long, Double or JSONObject.NULL.

Throws:

JSONException - if the input is malformed.

nextCleanInternal

private int nextCleanInternal()
                       throws JSONException

Throws:

JSONException

skipToEndOfLine

private void skipToEndOfLine()

Advances the position until after the next newline character. If the line is terminated by "\r\n", the '\n' must be consumed as whitespace by the caller.

nextString

public String nextString(char quote)
                  throws JSONException

Returns the string up to but not including quote, unescaping any character escape sequences encountered along the way. The opening quote should have already been read. This consumes the closing quote, but does not include it in the returned string.

Parameters:

quote - either ' or ".

Throws:

JSONException

readEscapeCharacter

private char readEscapeCharacter()
                          throws JSONException

Unescapes the character identified by the character or characters that immediately follow a backslash. The backslash '\' should have already been read. This supports both unicode escapes "u000A" and two-character escapes "\n".

Throws:

JSONException

readLiteral

private Object readLiteral()
                    throws JSONException

Reads a null, boolean, numeric or unquoted string literal value. Numeric values will be returned as an Integer, Long, or Double, in that order of preference.

Throws:

JSONException

nextToInternal

private String nextToInternal(String excluded)

Returns the string up to but not including any of the given characters or a newline character. This does not consume the excluded character.

readObject

private JSONObject readObject()
                       throws JSONException

Reads a sequence of key/value pairs and the trailing closing brace '}' of an object. The opening brace '{' should have already been read.

Throws:

JSONException

readArray

private JSONArray readArray()
                     throws JSONException

Reads a sequence of values and the trailing closing brace ']' of an array. The opening brace '[' should have already been read. Note that "[]" yields an empty array, but "[,]" returns a two-element array equivalent to "[null,null]".

Throws:

JSONException

syntaxError

public JSONException syntaxError(String message)

Returns an exception containing the given message plus the current position and the entire input string.

toString

public String toString()

Returns the current position and the entire input string.

Overrides:

toString in class Object

more

public boolean more()

Returns true until the input has been exhausted.

next

public char next()

Returns the next available character, or the null character '\0' if all input has been exhausted. The return value of this method is ambiguous for JSON strings that contain the character '\0'.

next

public char next(char c)
          throws JSONException

Returns the next available character if it equals c. Otherwise an exception is thrown.

Throws:

JSONException

nextClean

public char nextClean()
               throws JSONException

Returns the next character that is not whitespace and does not belong to a comment. If the input is exhausted before such a character can be found, the null character '\0' is returned. The return value of this method is ambiguous for JSON strings that contain the character '\0'.

Throws:

JSONException

next

public String next(int length)
            throws JSONException

Returns the next length characters of the input.

The returned string shares its backing character array with this tokener's input string. If a reference to the returned string may be held indefinitely, you should use new String(result) to copy it first to avoid memory leaks.

Throws:

JSONException - if the remaining input is not long enough to satisfy this request.

nextTo

public String nextTo(String excluded)

Returns the trimmed string holding the characters up to but not including the first of:

• any character in excluded
• a newline character '\n'
• a carriage return '\r'

The returned string shares its backing character array with this tokener's input string. If a reference to the returned string may be held indefinitely, you should use new String(result) to copy it first to avoid memory leaks.

Returns:

a possibly-empty string

nextTo

public String nextTo(char excluded)

Equivalent to nextTo(String.valueOf(excluded)).

skipPast

public void skipPast(String thru)

Advances past all input up to and including the next occurrence of thru. If the remaining input doesn't contain thru, the input is exhausted.

skipTo

public char skipTo(char to)

Advances past all input up to but not including the next occurrence of to. If the remaining input doesn't contain to, the input is unchanged.

back

public void back()

Unreads the most recent character of input. If no input characters have been read, the input is unchanged.

dehexchar

public static int dehexchar(char hex)

Returns the integer [0..15] value for the given hex character, or -1 for non-hex input.

Parameters:

hex - a character in the ranges [0-9], [A-F] or [a-f]. Any other character will yield a -1 result.