Package org.json
Class JSONWriter
- java.lang.Object
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- org.json.JSONWriter
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- Direct Known Subclasses:
JSONStringer
public class JSONWriter extends java.lang.Object
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 akey
method for adding keys before values in objects. There arearray
andendArray
methods that make and bound array values, andobject
andendObject
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
orobject
. 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
Fields Modifier and Type Field Description private boolean
comma
The comma flag determines if a comma should be output before the next value.private static int
maxdepth
protected char
mode
The current mode.private JSONObject[]
stack
The object/array stack.private int
top
The stack top index.protected java.lang.Appendable
writer
The writer that will receive the output.
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Constructor Summary
Constructors Constructor Description JSONWriter(java.lang.Appendable w)
Make a fresh JSONWriter.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description private JSONWriter
append(java.lang.String string)
Append a value.JSONWriter
array()
Begin appending a new array.private JSONWriter
end(char m, char c)
End something.JSONWriter
endArray()
End an array.JSONWriter
endObject()
End an object.JSONWriter
key(java.lang.String string)
Append a key.JSONWriter
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.JSONWriter
value(boolean b)
Append either the valuetrue
or the valuefalse
.JSONWriter
value(double d)
Append a double value.JSONWriter
value(long l)
Append a long value.JSONWriter
value(java.lang.Object object)
Append an object value.static java.lang.String
valueToString(java.lang.Object value)
Make a JSON text of an Object value.
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Field Detail
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maxdepth
private static final int maxdepth
- See Also:
- Constant Field Values
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comma
private boolean comma
The comma flag determines if a comma should be output before the next value.
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mode
protected char mode
The current mode. Values: 'a' (array), 'd' (done), 'i' (initial), 'k' (key), 'o' (object).
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stack
private final JSONObject[] stack
The object/array stack.
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top
private int top
The stack top index. A value of 0 indicates that the stack is empty.
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writer
protected java.lang.Appendable writer
The writer that will receive the output.
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Method Detail
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append
private JSONWriter append(java.lang.String string) throws JSONException
Append a value.- Parameters:
string
- A string value.- Returns:
- this
- Throws:
JSONException
- If the value is out of sequence.
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array
public JSONWriter array() throws JSONException
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).
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end
private JSONWriter end(char m, char c) throws JSONException
End something.- Parameters:
m
- Modec
- Closing character- Returns:
- this
- Throws:
JSONException
- If unbalanced.
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endArray
public JSONWriter endArray() throws JSONException
End an array. This method most be called to balance calls toarray
.- Returns:
- this
- Throws:
JSONException
- If incorrectly nested.
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endObject
public JSONWriter endObject() throws JSONException
End an object. This method most be called to balance calls toobject
.- Returns:
- this
- Throws:
JSONException
- If incorrectly nested.
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key
public JSONWriter key(java.lang.String string) throws JSONException
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
public JSONWriter object() throws JSONException
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).
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pop
private void pop(char c) throws JSONException
Pop an array or object scope.- Parameters:
c
- The scope to close.- Throws:
JSONException
- If nesting is wrong.
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push
private void push(JSONObject jo) throws JSONException
Push an array or object scope.- Parameters:
jo
- The scope to open.- Throws:
JSONException
- If nesting is too deep.
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valueToString
public static java.lang.String valueToString(java.lang.Object value) throws JSONException
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
public JSONWriter value(boolean b) throws JSONException
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
public JSONWriter value(double d) throws JSONException
Append a double value.- Parameters:
d
- A double.- Returns:
- this
- Throws:
JSONException
- If the number is not finite.
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value
public JSONWriter value(long l) throws JSONException
Append a long value.- Parameters:
l
- A long.- Returns:
- this
- Throws:
JSONException
- if a called function has an error
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value
public JSONWriter value(java.lang.Object object) throws JSONException
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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