org.json
Class JSONWriter

java.lang.Object
  extended by org.json.JSONWriter
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 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 20 levels deep.

This can sometimes be easier than using a JSONObject to build a string.

Version:
2010-12-24
Author:
JSON.org

Field Summary
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.io.Writer writer
          The writer that will receive the output.
 
Constructor Summary
JSONWriter(java.io.Writer w)
          Make a fresh JSONWriter.
 
Method Summary
private  JSONWriter append(java.lang.String string)
          Append a value.
 JSONWriter array()
          Begin appending a new array.
private  JSONWriter end(char mode, 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 value true or the value false.
 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.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

maxdepth

private static final int maxdepth
See Also:
Constant Field Values

comma

private boolean comma
The comma flag determines if a comma should be output before the next value.


mode

protected char mode
The current mode. Values: 'a' (array), 'd' (done), 'i' (initial), 'k' (key), 'o' (object).


stack

private JSONObject[] stack
The object/array stack.


top

private int top
The stack top index. A value of 0 indicates that the stack is empty.


writer

protected java.io.Writer writer
The writer that will receive the output.

Constructor Detail

JSONWriter

public JSONWriter(java.io.Writer w)
Make a fresh JSONWriter. It can be used to build one JSON text.

Method Detail

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.

array

public JSONWriter array()
                 throws JSONException
Begin appending a new array. All values until the balancing endArray will be appended to this array. The endArray 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

private JSONWriter end(char mode,
                       char c)
                throws JSONException
End something.

Parameters:
mode - Mode
c - Closing character
Returns:
this
Throws:
JSONException - If unbalanced.

endArray

public JSONWriter endArray()
                    throws JSONException
End an array. This method most be called to balance calls to array.

Returns:
this
Throws:
JSONException - If incorrectly nested.

endObject

public JSONWriter endObject()
                     throws JSONException
End an object. This method most be called to balance calls to object.

Returns:
this
Throws:
JSONException - If incorrectly nested.

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.

object

public JSONWriter object()
                  throws JSONException
Begin appending a new object. All keys and values until the balancing endObject will be appended to this object. The endObject 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

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.

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.

value

public JSONWriter value(boolean b)
                 throws JSONException
Append either the value true or the value false.

Parameters:
b - A boolean.
Returns:
this
Throws:
JSONException

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.

value

public JSONWriter value(long l)
                 throws JSONException
Append a long value.

Parameters:
l - A long.
Returns:
this
Throws:
JSONException

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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