Class JSONStringer
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 toendArray()
and every call toobject()
must have a matching call toendObject()
. - 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.
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.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescription(package private) static enum
Lexical scoping elements within this stringer, necessary to insert the appropriate separator characters (ie. -
Field Summary
FieldsModifier and TypeFieldDescriptionprivate final String
A string containing a full set of spaces for a single level of indentation, or null for no pretty printing.protected final StringBuilder
The output data, containing at most one top-level array or object.private final List
<JSONStringer.Scope> Unlike the original implementation, this stack isn't limited to 20 levels of nesting. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionarray()
Begins encoding a new array.private void
Inserts any necessary separators and whitespace before a name.private void
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, String closeBracket) Closes the current scope by appending any necessary whitespace and the given bracket.protected JSONStringer
Creates String representation of the key (property name) to this stringer Override this method to provide your own representation of the name.endArray()
Ends encoding the current array.Ends encoding the current object.Encodeskey
/value
pair to this stringer.Encodes the key (property name) to this stringer.private void
newline()
object()
Begins encoding a new object.(package private) JSONStringer
open
(JSONStringer.Scope empty, 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
toString()
Returns the encoded JSON string.value
(boolean value) Encodesvalue
to this stringer.value
(double value) Encodesvalue
to this stringer.value
(long value) Encodesvalue
to this stringer.Encodesvalue
.
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Field Details
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out
The output data, containing at most one top-level array or object. -
stack
Unlike the original implementation, this stack isn't limited to 20 levels of nesting. -
indent
A string containing a full set of spaces for a single level of indentation, or null for no pretty printing.
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Constructor Details
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JSONStringer
public JSONStringer() -
JSONStringer
public JSONStringer(int indentSpaces)
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Method Details
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array
Begins encoding a new array. Each call to this method must be paired with a call toendArray()
.- Returns:
- this stringer.
- Throws:
JSONException
- On internal errors. Shouldn't happen.
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endArray
Ends encoding the current array.- Returns:
- this stringer.
- Throws:
JSONException
- On internal errors. Shouldn't happen.
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object
Begins encoding a new object. Each call to this method must be paired with a call toendObject()
.- Returns:
- this stringer.
- Throws:
JSONException
- On internal errors. Shouldn't happen.
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endObject
Ends encoding the current object.- Returns:
- this stringer.
- Throws:
JSONException
- On internal errors. Shouldn't happen.
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open
Enters a new scope by appending any necessary whitespace and the given bracket.- Throws:
JSONException
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close
JSONStringer close(JSONStringer.Scope empty, JSONStringer.Scope nonempty, String closeBracket) throws JSONException Closes the current scope by appending any necessary whitespace and the given bracket.- Throws:
JSONException
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peek
Returns the value on the top of the stack.- Throws:
JSONException
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replaceTop
Replace the value on the top of the stack with the given value. -
value
Encodesvalue
.- Parameters:
value
- aJSONObject
,JSONArray
, String, Boolean, Integer, Long, Double or null. May not beNaNs
orinfinities
.- Returns:
- this stringer.
- Throws:
JSONException
- On internal errors. Shouldn't happen.
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value
Encodesvalue
to this stringer.- Parameters:
value
- The value to encode.- Returns:
- this stringer.
- Throws:
JSONException
- On internal errors. Shouldn't happen.
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value
Encodesvalue
to this stringer.- Parameters:
value
- a finite value. May not beNaNs
orinfinities
.- Returns:
- this stringer.
- Throws:
JSONException
- On internal errors. Shouldn't happen.
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value
Encodesvalue
to this stringer.- Parameters:
value
- The value to encode.- Returns:
- this stringer.
- Throws:
JSONException
- If we have an internal error. Shouldn't happen.
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entry
Encodeskey
/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.
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string
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newline
private void newline() -
createKey
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.
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key
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.
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beforeKey
Inserts any necessary separators and whitespace before a name. Also adjusts the stack to expect the key's value.- Throws:
JSONException
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beforeValue
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
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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.
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