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Need a real simple way to read json value in java

I am currently writing an application in Java, and am struggling to extract the values from a String which is in a JSON format.
Could someone help me with the easiest, most simplest way to extract data from this string? I'd prefer not to use external library if at all possible.
{"exchange":{"status":"Enabled","message":"Broadband on Fibre Technology","exchange_code":"NIWBY","exchange_name":"WHITEABBEY"},"products":[{"name":"20CN ADSL Max","likely_down_speed":1.5,"likely_up_speed":0.15,"availability":true....
Could someone explain how I could return the "likely down speed" of "20CN ADSL Max for example?
Thanks

Currently , there is no way in Java to parse json without an external lib (or your own implementation).
The org.json library is a standard when working with JSON.
You can use this snippet along with the library to achieve what you asked:
JSONObject obj = new JSONObject(" .... ");
JSONArray arr = obj.getJSONArray("products");
for (int i = 0; i < arr.length(); i++) {
String name = arr.getJSONObject(i).getString("name");
if ( name.equals("20CN ADSL Max") ) {
String s = arr.getJSONObject(i).getString("likely down speed");
}
}
Hope this helps.

For sure it's possible to do the parsing yourself, but it'll be much faster if you rely upon an existing library such as org.json.
With that, you can easily convert the string into a JSON object and extract all the fields you need.
If an existing library is not an option, you'll need to build yourself the tree describing the object in order to extract the pair key-values

While this may seem like a very simple, straightforward task, it gets rather complicated rather quickly.
Check out the SO thread How to parse JSON in Java. There is unfortunately not a single, clear solution to that question as shown in that thread. But I guess the org.json library seems to be the most popular solution.
If your application needs to handle arbitrary JSON, I would advise against trying to build your own parser.
Whatever your objections are to using an external library, get over them.

Explain the functionality of JSON

I think it is better to understand why I have so many problems with JSON that I explain you what my goal is:
I work with Googles App Engine. There I want to store data. The data looks like
user - username
question - question
date1 - date1
date2 - date2
An Android App have the "simple" function to: Send the data which the user has entered and reviece the data from the complete database.
Ok, fine.
So I searched for a good "API" for that. The question about that was: "how can I read the data" and "how can I sent". The "simple" anwere was: use JSON.. . Many people say's that to me.
The first step was to show the data from the database. I write in python that:
json.dumps({"info": [{'user': 'username1', 'question': 'question1', 'date1':'date1', 'date2':'date1'}, {'user': 'username2', 'question': 'question2', 'date1':'date2', 'date2':'date2'}]})
It works. On the Client site I write in Java these:
JSONObject ob = new JSONObject(result);
JSONArray arNames = ob.getJSONArray("info");
for(int i = 0; i < arNames.length(); i++){
JSONObject c = arNames.getJSONObject(i);
Log.i("name", c.getString("name"));
Log.i("frage", c.getString("question"));
}
These works also.
But (and now the main question about the thread!):
Why we use JSON to format?! Why? I can with this data an other simple "API" without the JSON libarys and classes.
Example:
If I say on the Server site only:
!user:user;question:question;date1:date1;date2:date2
!user:user1;question:question1;data2:date3;date2:date3
... and so one...
On the Client site the same:
[READ THE DATA WITH ClientHTTP]
String[] all = result.Split("!");
for(int i = 0; i<all.length; i+= 1)
{
String[] split2 = all[i].Split(";");
String[] user = split2[0].Split(":");
// user[1] holds now the user
String[] split3 = split2[1].Split(";");
String[] questinn = split3.Split(":");
// question[1] holds now the question
... AND SO ONE!
So, why I use JSON? My option or example do the same. But with my own Syntax..
Thank you for help

JSON is a standard format and it's implementations make it easy to use -- No split() and other stuff necessary. Also, it's supported by all kinds of programming languages (like Python and Java in your own example) and so it provides a simple way to exchange data between completly different systems.
And it's well thought out and could for example also handle questions with ':' or ';' in it. A case where your suggested solution would fail.

I am not sure with JSON but there alreday was a thread explaining JSON (google knows everything). Maybe you can find some help here:
What is JSON and why would I use it?
http://www.copterlabs.com/blog/json-what-it-is-how-it-works-how-to-use-it/
EDIT: I forgot to answer the question why not to use your own function. Of course you can use it and it works. But a lot of services give a JSON to you. It is like a standard. Furthermore there is an JavaClass. So you do not have to do the work which others already have done (see: http://goo.gl/9X4HU)
Best regards

Don't do it by hand, it's error-prione and violates DRY (don't repeat yourself). Instead:
On server use a REST framework that automatically produces JSON. For example RESTEasy. Search the net for examples.
On Android use either built in support for JSON or better use on of well-known and tested libs: GSON or Jackson. See some speed comparisons. Alternativelly you can use Spring Android, which mashes networking+JSON in one easy to use package.

I use JSON in Android because it is lightweight data format which I can easily convert to Java objects using this google library.
You always have 2 possibilities - to use some library, or to write the code by yourself. I'm not saying that using the library is always an option, but in many cases it can save your time and reduce errors. It's up to you to decide.

Is it possible to serialize an object into a plain text string and send it as a string then convert it back?

As the title says. I'm sending a message, from my server, into a proxy which is outside of my control which then sends it onto my application. All I can do is send and receive strings. Is it possible to serialize to a plain string and send in this way without an input/output stream as you would normally have?
TIA
A little more info:
public class myClass implements java.io.Serializable {
int h = "ccc";
int i = "bbbb";
String myString = "aaaa";
}
I have this class, for example. Now I want to serialize it and send it as a string inside my HTTPpost and send to the proxy, can't do anything about this stage:
HttpPost post = new HttpPost("http://www.myURL.com/send.php?msg="+msg);
Then receive the msg as a string on the other side and convert it back.
Is that easily done without to many other library?

Yes.
This is done every day using JSON and XML, just to name a few formats of strings that are easily formatted and parsed. (Read about JAXRS to know about a way to use JSON formatted strings to do this and do the transfers. Or, read about JAXB which will format as XML but doesn't halp with the communication of the strings.)
You can do it in CSV format.
You can do it in fixed with fields of characters.
Morse code isn't much of a different concept only it starts with strings and converts to short and long beeps.
The way it works is this:
There is some code to which you pass an object and it returns a string in a known format.
You send the string to the other server somehow. Some ways to send strings have limits on the length.
The other server receives the string.
Using its knowledge of the format, that other server parses out the string contents and uses it.
Some notes:
If both servers use Java (or C# or Python or PHP or whatever) the formatting and parsing become symetrical. You start with a Java object of some type and end up with a Java object in the other JVM of the same type. But that is not a given. You can store values in a custom POJO in one server and a Map in the other.
If you write code to format and parse, it seems really easy as long as the contents are simple and you don't run afoul of transmission rules. For example, if you send in the query part of an HTTP get, you can't have any ampersand characters in the string.
If you use an existing library, you take advantage of everyone else's acquired knowlege of how to do this without error.
If you use a standard format for the string, it is easy to explain what's going on to someone else. If your project works, a third server might want to be in the communication loop and if it's controlled by someone else ...
Formatting is easier than parsing. There are lots of pitfalls that other people have already solved. If you are doing this to learn ways not to do things and improve your own knowledge base, by all means, do it yourself. If you want rock solid performance, use an existing and standard library and format.

Take a look at XStream. It serializes into XML, and is very simple to use.
Take a look at there Two Minute Tutorial

Yes it is possible. You can use ajax to to serialize the string to a json object and have it back to the server using an ajax.post event (javascript event).

JSON parsing in java

I have no idea how to parse JSON in java(or anything else). I've seen some tutorials but I can't get it straight.
I am trying to get title="Fabiola Jean and Laurent Lundy commented on a photo that you're tagged". All I need is to know how to create a getTitle() method
this is the JSON I want to parse:
Connection[data=[Notification[id=notif__161136848 metadata=null
title=Fabiola Jean and Laurent Lundy commented on a photo that you're tagged in. type=null]]
nextPageUrl=https://graph.facebook.com/811204509/notifications?fields
=title&value=1&format=json&redirect=1&access_token=MY_TOKEN&__paging_token=
notif__161136848
previousPageUrl=https://graph.facebook.com/811204509/notifications?fields=title
&value=1&format=json&redirect=1&access_token=MY_TOKEN&limit=5000&since=1342109329&
__paging_token=notif__161136848&__previous=1 next=true previous=true]

First, the code you put in your question is absolutely not valid JSON. I'm not quite sure what it is, and it does not appear to be easily parsable.
Assuming you are trying to parse actual JSON you almost certainly want to use a 3rd party library instead of writing the code using string manipulation functions.
Gson would be my first recommendation, and Jackson is another alternative you might want to look at.

How do I convert a Java Hashtable to an NSDictionary (obj-C)?

At the server end (GAE), I've got a java Hashtable.
At the client end (iPhone), I'm trying to create an NSDictionary.
myHashTable.toString() gets me something that looks darned-close-to-but-not-quite-the-same-as [myDictionary description]. If they were the same, I could write the string to a file and do:
NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:tmpFile];
I could write a little parser in obj-C to deal with myHashtable.toString(), but I'm sort-of hoping that there's a shortcut already built into something, somewhere -- I just can't seem to find it.
(So, being a geek, I'll spend far longer searching the web for a shortcut than it would take me to write & debug the parser... ;)
Anyway -- hints?
Thanks!

I would convert the Hashtable into something JSON-like and take it on the iPhone side.
Hashtable.toString() is not ideal, it will have problem with spaces, comma and quotation marks.
For JSON-to-NSDictionary, you can find the json-framework tools under http://www.json.org/

As j-16 SDiZ mentioned, you need to serialize your hashtable. It can be to json, xml or some other format. Once serialized, you need to deserialize them into an NSDictionary. JSON is probably the easiest format to do this with plenty of libraries for both Objective-C and Java. http://json.org has a list of libraries.