Package org.json
Class JSONWriter
java.lang.Object
org.json.JSONWriter
- Direct Known Subclasses:
JSONStringer
JSONWriter provides a quick and convenient way of producing JSON text.
The texts produced strictly conform to JSON syntax rules. No whitespace is
added, so the results are ready for transmission or storage. Each instance of
JSONWriter can produce one JSON text.
A JSONWriter instance provides a value
method for appending
values to the
text, and a key
method for adding keys before values in objects. There are array
and endArray
methods that make and bound array values, and
object
and endObject
methods which make and bound
object values. All of these methods return the JSONWriter instance,
permitting a cascade style. For example,
new JSONWriter(myWriter) .object() .key("JSON") .value("Hello, World!") .endObject();which writes
{"JSON":"Hello, World!"}
The first method called must be array
or object
.
There are no methods for adding commas or colons. JSONWriter adds them for
you. Objects and arrays can be nested up to 200 levels deep.
This can sometimes be easier than using a JSONObject to build a string.
- Version:
- 2016-08-08
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate boolean
The comma flag determines if a comma should be output before the next value.private static final int
protected char
The current mode.private final JSONObject[]
The object/array stack.private int
The stack top index.protected Appendable
The writer that will receive the output. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate JSONWriter
Append a value.array()
Begin appending a new array.private JSONWriter
end
(char m, char c) End something.endArray()
End an array.End an object.Append a key.object()
Begin appending a new object.private void
pop
(char c) Pop an array or object scope.private void
push
(JSONObject jo) Push an array or object scope.value
(boolean b) Append either the valuetrue
or the valuefalse
.value
(double d) Append a double value.value
(long l) Append a long value.Append an object value.static String
valueToString
(Object value) Make a JSON text of an Object value.
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Field Details
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maxdepth
private static final int maxdepth- See Also:
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comma
private boolean commaThe comma flag determines if a comma should be output before the next value. -
mode
protected char modeThe current mode. Values: 'a' (array), 'd' (done), 'i' (initial), 'k' (key), 'o' (object). -
stack
The object/array stack. -
top
private int topThe stack top index. A value of 0 indicates that the stack is empty. -
writer
The writer that will receive the output.
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Constructor Details
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JSONWriter
Make a fresh JSONWriter. It can be used to build one JSON text.- Parameters:
w
- an appendable object
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Method Details
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append
Append a value.- Parameters:
string
- A string value.- Returns:
- this
- Throws:
JSONException
- If the value is out of sequence.
-
array
Begin appending a new array. All values until the balancingendArray
will be appended to this array. TheendArray
method must be called to mark the array's end.- Returns:
- this
- Throws:
JSONException
- If the nesting is too deep, or if the object is started in the wrong place (for example as a key or after the end of the outermost array or object).
-
end
End something.- Parameters:
m
- Modec
- Closing character- Returns:
- this
- Throws:
JSONException
- If unbalanced.
-
endArray
End an array. This method most be called to balance calls toarray
.- Returns:
- this
- Throws:
JSONException
- If incorrectly nested.
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endObject
End an object. This method most be called to balance calls toobject
.- Returns:
- this
- Throws:
JSONException
- If incorrectly nested.
-
key
Append a key. The key will be associated with the next value. In an object, every value must be preceded by a key.- Parameters:
string
- A key string.- Returns:
- this
- Throws:
JSONException
- If the key is out of place. For example, keys do not belong in arrays or if the key is null.
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object
Begin appending a new object. All keys and values until the balancingendObject
will be appended to this object. TheendObject
method must be called to mark the object's end.- Returns:
- this
- Throws:
JSONException
- If the nesting is too deep, or if the object is started in the wrong place (for example as a key or after the end of the outermost array or object).
-
pop
Pop an array or object scope.- Parameters:
c
- The scope to close.- Throws:
JSONException
- If nesting is wrong.
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push
Push an array or object scope.- Parameters:
jo
- The scope to open.- Throws:
JSONException
- If nesting is too deep.
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valueToString
Make a JSON text of an Object value. If the object has an value.toJSONString() method, then that method will be used to produce the JSON text. The method is required to produce a strictly conforming text. If the object does not contain a toJSONString method (which is the most common case), then a text will be produced by other means. If the value is an array or Collection, then a JSONArray will be made from it and its toJSONString method will be called. If the value is a MAP, then a JSONObject will be made from it and its toJSONString method will be called. Otherwise, the value's toString method will be called, and the result will be quoted.Warning: This method assumes that the data structure is acyclical.
- Parameters:
value
- The value to be serialized.- Returns:
- a printable, displayable, transmittable representation of the
object, beginning with
{
(left brace) and ending with}
(right brace). - Throws:
JSONException
- If the value is or contains an invalid number.
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value
Append either the valuetrue
or the valuefalse
.- Parameters:
b
- A boolean.- Returns:
- this
- Throws:
JSONException
- if a called function has an error
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value
Append a double value.- Parameters:
d
- A double.- Returns:
- this
- Throws:
JSONException
- If the number is not finite.
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value
Append a long value.- Parameters:
l
- A long.- Returns:
- this
- Throws:
JSONException
- if a called function has an error
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value
Append an object value.- Parameters:
object
- The object to append. It can be null, or a Boolean, Number, String, JSONObject, or JSONArray, or an object that implements JSONString.- Returns:
- this
- Throws:
JSONException
- If the value is out of sequence.
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