org.json

Class JSONWriter

java.lang.Object

org.json.JSONWriter

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

Direct Known Subclasses:

JSONStringer

public class JSONWriter
extends java.lang.Object
implements java.io.Closeable

JSONWriter provides a quick and convenient way of producing JSON text. The texts produced strictly conform to JSON syntax rules. By default, 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, unless this object has been constructed with allowSimpleValues set to true.

There are no methods for adding commas or colons. JSONWriter adds them for you. Objects and arrays can be nested arbitrarily deep.

This can be less memory intensive than using a JSONObject to build a string.

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	done Indicate when writing has finished.
protected java.lang.Appendable	writer The writer that will receive the output.

Constructor Summary

Constructors

Constructor and Description
JSONWriter(java.lang.Appendable w) Make a fresh JSONWriter.
JSONWriter(java.lang.Appendable w, boolean allowSimpleValues) Make a fresh JSONWriter.
JSONWriter(java.lang.Appendable w, int indentFactor) Make a fresh JSONWriter with the given indent factor.
JSONWriter(java.lang.Appendable w, int indentFactor, int indent) Make a fresh JSONWriter with the given indent factor and initial indentation.
JSONWriter(java.lang.Appendable w, int indentFactor, int indent, boolean allowSimpleValues) Make a fresh JSONWriter with the given indent factor and initial indentation.

Method Summary

Modifier and Type	Method and Description
JSONWriter	array() Begin appending a new array.
void	close() Asserts the JSON writer is finished, and close any underlying Closeable writer.
JSONWriter	endArray() End an array.
JSONWriter	endObject() End an object.
JSONWriter	entries(java.util.Map<?,?> kvPairs) Append a sequence of keys and values in an object.
JSONWriter	key(java.lang.String string) Append a key.
JSONWriter	nullValue() Append a null value.
JSONWriter	object() Begin appending a new object.
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.
JSONWriter	values(java.lang.Iterable<?> values) Append a sequence of values into an array.

Methods inherited from class java.lang.Object

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

Field Detail

done

protected boolean done

Indicate when writing has finished.

writer

protected final java.lang.Appendable writer

The writer that will receive the output.

Constructor Detail

JSONWriter

public JSONWriter(java.lang.Appendable w)

Make a fresh JSONWriter. It can be used to build one JSON text.

Parameters:

w - the Writer to which JSON content will be written

JSONWriter

public JSONWriter(java.lang.Appendable w,
                  boolean allowSimpleValues)

Make a fresh JSONWriter. It can be used to build one JSON text.

Parameters:

w - the Writer to which JSON content will be written

allowSimpleValues - true to allow the root value to be a simple value, otherwise false to only allow objects and arrays at the root level

JSONWriter

public JSONWriter(java.lang.Appendable w,
                  int indentFactor)

Make a fresh JSONWriter with the given indent factor. It can be used to build one JSON text with pretty-printing.

Parameters:

w - the Writer to which JSON content will be written

indentFactor - indent level, or 0 for compact output

JSONWriter

public JSONWriter(java.lang.Appendable w,
                  int indentFactor,
                  int indent)

Make a fresh JSONWriter with the given indent factor and initial indentation. It can be used to build one JSON text with pretty-printing.

Parameters:

w - the Writer to which JSON content will be written

indentFactor - indent level, or 0 for compact output

indent - initial indent

JSONWriter

public JSONWriter(java.lang.Appendable w,
                  int indentFactor,
                  int indent,
                  boolean allowSimpleValues)

Make a fresh JSONWriter with the given indent factor and initial indentation. It can be used to build one JSON text with pretty-printing.

Parameters:

w - the Writer to which JSON content will be written

indentFactor - indent level, or 0 for compact output

indent - initial indent

allowSimpleValues - true to allow the root value to be a simple value, otherwise false to only allow objects and arrays at the root level

Method Detail

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).

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).

nullValue

public JSONWriter nullValue()
                     throws JSONException

Append a null value.

Returns:

this

Throws:

JSONException - there was a problem writing the null value

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 - there was a problem writing the boolean value

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 - there was a problem writing the long value

value

public JSONWriter value(java.lang.Object object)
                 throws JSONException

Append an object value.

Parameters:

object - The object to appendString. 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.

values

public JSONWriter values(java.lang.Iterable<?> values)
                  throws JSONException

Append a sequence of values into an array.

Parameters:

values - The objects to appendString. They can be null, or a Boolean, Number, String, JSONObject, or JSONArray, or an object that implements JSONString.

Returns:

this

Throws:

JSONException - If a value is out of place. For example, a value occurs where a key is expected.

entries

public JSONWriter entries(java.util.Map<?,?> kvPairs)
                   throws JSONException

Append a sequence of keys and values in an object. The key will be associated with the corresponding value. In an object, every value must be associated with a key.

Parameters:

kvPairs - The objects to appendString. The values can be null, or a Boolean, Number, String, JSONObject, or JSONArray, or an object that implements JSONString.

Returns:

this

Throws:

JSONException - If a key or value is out of place. For example, keys do not belong in arrays or if the key is null.

close

public void close()
           throws java.io.IOException

Asserts the JSON writer is finished, and close any underlying Closeable writer.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.io.IOException - the writer cannot be closed