JSONObject should extend LinkedHashMap to preserve order of key-value pairs about json-simple HOT 7 CLOSED

You can provide a ContainerFactory to get a LinkedHashMap during decoding:
http://code.google.com/p/json-simple/wiki/DecodingExamples#Example_4_-_Container
_factory

And then use JSONValue.toJSONString() to encode the object: 
http://code.google.com/p/json-simple/wiki/EncodingExamples#Example_1-3_-_Encode_
a_JSON_object_-_Using_Map

Then you will get what you expect.

Should'nt this be considered a possible fix for the next release?

Just to note that LinkedHashMaps are somewhat slower for get and put operations 
than regular HashMaps. So some people may be interested in keeping good 
performance than maintaining object member order.

I attached 2 performance tests for constructing hash-map/linked-hash-map:
  1) inserts 1.5M integers into each map, and
  2) creates many(1.5M) small(<10 keys) maps.

Here are the results:
  Many-keys(1500000)   delay: mean(-14,63%), stdev(1,86%)
  Many-hashes(1500000) delay: mean(23,40%),  stdev(5,18%)

Interestingly enough, linked-hash is actually faster(!) when inserting 
many-keys.
I'm suspecting it is due to the improved re-sizing of linked-hash-tables.

But it is ~23% slower when creating a lot smaller hashes.

I expect searching into the hashes to be exactly the same.


TEST-ENV:
  java.version=1.6.0_22, 
  java.runtime.version=1.6.0_22-b04, 
  java.runtime.name=Java(TM) SE Runtime Environment, 
  java.vendor.url=http://java.sun.com/,
  java.vm.version=17.1-b03, java.vm.vendor=Sun Microsystems Inc.,
  java.vm.info=mixed mode, 
  java.vm.name=Java HotSpot(TM) Server VM, 
  sun.management.compiler=HotSpot Tiered Compilers, 
  os.arch=i386,
  os.version=2.6.36-ck-r3, 
  os.name=Linux

Issue 40 has been merged into this issue.

If you are using the Transformer code to collect the Json Strings as
JSONObject +JSONArrays, would it not be better to have theJ SONObject extend
LinkedHashMap as ooposed HashMap to preserve the order of elements

regds,
Chiths