Package com.github.openjson

Class JSONStringer

java.lang.Object

com.github.openjson.JSONStringer

public class JSONStringer
extends java.lang.Object

Implements JSONObject.toString() and JSONArray.toString(). Most application developers should use those methods directly and disregard this API. For example:

 JSONObject object = ...
 String json = object.toString();

Stringers only encode well-formed JSON strings. In particular:

• The stringer must have exactly one top-level array or object.
• Lexical scopes must be balanced: every call to array() must have a matching call to endArray() and every call to object() must have a matching call to endObject().
• Arrays may not contain keys (property names).
• Objects must alternate keys (property names) and values.
• Values are inserted with either literal value calls, or by nesting arrays or objects.

Calls that would result in a malformed JSON string will fail with a JSONException.

This class provides no facility for pretty-printing (ie. indenting) output. To encode indented output, use JSONObject.toString(int) or JSONArray.toString(int).

Some implementations of the API support at most 20 levels of nesting. Attempts to create more than 20 levels of nesting may fail with a JSONException.

Each stringer may be used to encode a single top level value. 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.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	JSONStringer.Scope	Lexical scoping elements within this stringer, necessary to insert the appropriate separator characters (ie.

Field Summary

Fields

Modifier and Type	Field	Description
private java.lang.String	indent	A string containing a full set of spaces for a single level of indentation, or null for no pretty printing.
protected java.lang.StringBuilder	out	The output data, containing at most one top-level array or object.
private java.util.List<JSONStringer.Scope>	stack	Unlike the original implementation, this stack isn't limited to 20 levels of nesting.

Constructor Summary

Constructors

Constructor	Description
JSONStringer()
JSONStringer(int indentSpaces)

Method Summary

Modifier and Type	Method	Description
JSONStringer	array()	Begins encoding a new array.
private void	beforeKey()	Inserts any necessary separators and whitespace before a name.
private void	beforeValue()	Inserts any necessary separators and whitespace before a literal value, inline array, or inline object.
(package private) JSONStringer	close(JSONStringer.Scope empty, JSONStringer.Scope nonempty, java.lang.String closeBracket)	Closes the current scope by appending any necessary whitespace and the given bracket.
protected JSONStringer	createKey(java.lang.String name)	Creates String representation of the key (property name) to this stringer Override this method to provide your own representation of the name.
JSONStringer	endArray()	Ends encoding the current array.
JSONStringer	endObject()	Ends encoding the current object.
JSONStringer	entry(java.util.Map.Entry<java.lang.String,java.lang.Object> entry)	Encodes key/value pair to this stringer.
JSONStringer	key(java.lang.String name)	Encodes the key (property name) to this stringer.
private void	newline()
JSONStringer	object()	Begins encoding a new object.
(package private) JSONStringer	open(JSONStringer.Scope empty, java.lang.String openBracket)	Enters a new scope by appending any necessary whitespace and the given bracket.
private JSONStringer.Scope	peek()	Returns the value on the top of the stack.
private void	replaceTop(JSONStringer.Scope topOfStack)	Replace the value on the top of the stack with the given value.
private void	string(java.lang.String value)
java.lang.String	toString()	Returns the encoded JSON string.
JSONStringer	value(boolean value)	Encodes value to this stringer.
JSONStringer	value(double value)	Encodes value to this stringer.
JSONStringer	value(long value)	Encodes value to this stringer.
JSONStringer	value(java.lang.Object value)	Encodes value.

Methods inherited from class java.lang.Object

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

Field Detail

out

protected final java.lang.StringBuilder out

The output data, containing at most one top-level array or object.

stack

private final java.util.List<JSONStringer.Scope> stack

Unlike the original implementation, this stack isn't limited to 20 levels of nesting.

indent

private final java.lang.String indent

A string containing a full set of spaces for a single level of indentation, or null for no pretty printing.

Constructor Detail

JSONStringer

public JSONStringer()

JSONStringer

public JSONStringer(int indentSpaces)

Method Detail

array

public JSONStringer array()
                   throws JSONException

Begins encoding a new array. Each call to this method must be paired with a call to endArray().

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

endArray

public JSONStringer endArray()
                      throws JSONException

Ends encoding the current array.

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

object

public JSONStringer object()
                    throws JSONException

Begins encoding a new object. Each call to this method must be paired with a call to endObject().

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

endObject

public JSONStringer endObject()
                       throws JSONException

Ends encoding the current object.

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

open

JSONStringer open(JSONStringer.Scope empty,
                  java.lang.String openBracket)
           throws JSONException

Enters a new scope by appending any necessary whitespace and the given bracket.

Throws:

JSONException

close

JSONStringer close(JSONStringer.Scope empty,
                   JSONStringer.Scope nonempty,
                   java.lang.String closeBracket)
            throws JSONException

Closes the current scope by appending any necessary whitespace and the given bracket.

Throws:

JSONException

peek

private JSONStringer.Scope peek()
                         throws JSONException

Returns the value on the top of the stack.

Throws:

JSONException

replaceTop

private void replaceTop(JSONStringer.Scope topOfStack)

Replace the value on the top of the stack with the given value.

value

public JSONStringer value(java.lang.Object value)
                   throws JSONException

Encodes value.

Parameters:

value - a JSONObject, JSONArray, String, Boolean, Integer, Long, Double or null. May not be NaNs or infinities.

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

value

public JSONStringer value(boolean value)
                   throws JSONException

Encodes value to this stringer.

Parameters:

value - The value to encode.

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

value

public JSONStringer value(double value)
                   throws JSONException

Encodes value to this stringer.

Parameters:

value - a finite value. May not be NaNs or infinities.

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

value

public JSONStringer value(long value)
                   throws JSONException

Encodes value to this stringer.

Parameters:

value - The value to encode.

Returns:

this stringer.

Throws:

JSONException - If we have an internal error. Shouldn't happen.

entry

public JSONStringer entry(java.util.Map.Entry<java.lang.String,java.lang.Object> entry)

Encodes key/value pair to this stringer.

Parameters:

entry - The entry to encode.

Returns:

this stringer.

Throws:

JSONException - If we have an internal error. Shouldn't happen.

string

private void string(java.lang.String value)

newline

private void newline()

createKey

protected JSONStringer createKey(java.lang.String name)

Creates String representation of the key (property name) to this stringer Override this method to provide your own representation of the name.

Parameters:

name - the name of the forthcoming value.

Returns:

this stringer.

key

public JSONStringer key(java.lang.String name)
                 throws JSONException

Encodes the key (property name) to this stringer.

Parameters:

name - the name of the forthcoming value. May not be null.

Returns:

this stringer.

Throws:

JSONException - on internal errors, shouldn't happen.

beforeKey

private void beforeKey()
                throws JSONException

Inserts any necessary separators and whitespace before a name. Also adjusts the stack to expect the key's value.

Throws:

JSONException

beforeValue

private void beforeValue()
                  throws JSONException

Inserts any necessary separators and whitespace before a literal value, inline array, or inline object. Also adjusts the stack to expect either a closing bracket or another element.

Throws:

JSONException

toString

public java.lang.String toString()

Returns the encoded JSON string.

If invoked with unterminated arrays or unclosed objects, this method's return value is undefined.

Warning: although it contradicts the general contract of Object.toString(), this method returns null if the stringer contains no data.

Overrides:

toString in class java.lang.Object