JSON4processing Unhandled exception type JSON Exception depend on OS [update]

Makio135

JSON4processing Unhandled exception type JSON Exception depend on OS [update]

in Contributed Library Questions • 1 year ago

Hello all,

I'd like to use the Json4Processing library for a project, but am stuck with an "Unhandled exception type JSON Exception" when using JSONObject.put() method.

import org.json.*;
JSONObject obj;
void setup() {
obj = new JSONObject();
obj.put("key", "value"); Unhandled exception type JSON Exception
println(obj);
}
void draw(){};

Json4Processing v0.1.3 lib is correctly installed (i can import it from the Import Menu and view the examples in the Examples Menu...) and the error appears in the examples too.

The lib seems to work well with JSONArray but the problem is with JSONObject: I can create instances but can't use the JSONObject. put() method.

I also tried to add: "import org.json.JSONException;" with the same result.

Don't know why it doesn't work for me when it seems no one had this problem before, so any hint is welcomed.

Thanks.

http://makio.free.fr/

Replies(15)

Makio135

Re: JSON4processing Unhandled exception type JSON Exception

1 year ago

Since JSON4Processing is an implementation from JSON-Java,

i downloaded sources from JSON-Java,

put .java files next to my sketch.pde,

removed "import org.json.*;"

commented "package org.json;" from .java files;

-> I get the exact same Unhandled exception type JSON Exception with JSONObject.put()...

Could it be a problem with my config?

Windows 7, processing1.5.1, JavaRE 6

http://makio.free.fr/

PhiLho

Re: JSON4processing Unhandled exception type JSON Exception

1 year ago

Lot of people stumble upon this message, I will make a Technical FAQ page about it...

You believe it is a runtime exception like NullPointerException or ArrayIndexOutOfBoundsException, but that's not the case. It isn't produced while running the sketch, but at compilation time, actually.
Processing coders doesn't know well this message, because Processing carefully avoids to throw exceptions, even more checked exceptions.
NPE or AIOOBE are unchecked exceptions, ie. there is no need to catch them.
IOException is an example of checked exception: you have to catch them or to re-throw them. The JSONException seems to be another one. Checked exceptions are likely to happen upon some (external, in general) conditions, like no file or not access to a file, or no network, or badly formated data (JSON here), etc.
So, the cure to this message is that you have to surround the line that can throw the exception with a try { ... } catch (JSONException e) { ... } construct.
I don't have time to give a full course here now, but I will write this FAQ article...

(later!)

Makio135

Re: JSON4processing Unhandled exception type JSON Exception

1 year ago

As always, a great answer from you, thank you very much!

Then, from your answer, plus looking at the source, the actual way to use JSONObject.put() is:

import org.json.*;
JSONObject obj;
void setup() {
obj = new JSONObject();
try {
obj.put("key", "value");
obj.put("key2", "value2");
}
catch(JSONException e) {
e.getCause();
}
println(obj); // prints: {"key2":"value2","key":"value"}
}
void draw() {
}

As you wrote Exception is not (much) covered for Processing coders. I'll be looking for your article. Thanks!

That aside, since you're a moderator, could i suggest a [Snippet/Ressources] section in the Forum to share some utility functions or tricks like @AmnonOwed did in his article 25 LIFE-SAVING TIPS FOR PROCESSING or even tutorials?

http://makio.free.fr/

PhiLho

Re: JSON4processing Unhandled exception type JSON Exception

1 year ago

Not a bad idea, but the Share you Work is actually here for such resources, not only to show off complete programs.

PhiLho

Re: JSON4processing Unhandled exception type JSON Exception

1 year ago

I forgot, but I made in the Technical FAQ a link to the page What is an exception a long time ago... It was time to create the page, so I did it.

Feedback is welcome!

a__g

Re: JSON4processing Unhandled exception type JSON Exception

11 months ago

This is strange, testing this on my computer now and I get no "unhandled exception" errors - nor can I find any exceptions being thrown by any of the put methods inside the JSONObject class. Are you absolutely positive you've got the latest version installed?

Works on both processing 1.5.1 and 2.0b5 for me. I'm on Windows 7, with Java7 installed (but the lib is compiled using 1.6)

Makio135

Re: JSON4processing Unhandled exception type JSON Exception

11 months ago

Json4Processing v0.1.3 downloaded here: https://github.com/agoransson/JSON-processing/downloads

By the way your github Json-processing folder contains folders from the Processing library template (.settings data lib resources web) which make it a bit messy when one wants to fork it

http://makio.free.fr/

a__g

Re: JSON4processing Unhandled exception type JSON Exception

11 months ago

Yeah, I know it's a bit messy - I should fix the ignores.

Could you post a detailed error log? Perhaps I can find something out from that and hopefully fix the remaining JSONException.

Makio135

Re: JSON4processing Unhandled exception type JSON Exception

11 months ago

The problem is i get no error log in the console, not even in the Java console, i only have Unhandled exception type JSON Exception

Makio135
http://makio135.com/

Makio135

Re: JSON4processing Unhandled exception type JSON Exception

11 months ago

Back to the subject.

I tried every exemple, and tried to have them work following the try/catch system:

- JSONObject.put() doesn't work without try/catch whereas JSONArray.put() works fine without:

import org.json.*;
JSONArray arr;
JSONObject obj, obj2;
void setup() {
// Creating nested JSONObject :OK
obj = new JSONObject();
obj2 = new JSONObject();
try {
int i = 12;
obj.put("key1", i);
String s = "value";
obj.put("key2", s);
boolean b = true;
obj2.put("key3", b);
color c = color(255);
obj2.put("key4", hex(c, 6));
obj.put("obj2", obj2);
}
catch(JSONException e) {
e.getCause();
}
println(obj);
// prints: {"key2":"value","obj2":{"key4":"FFFFFF","key3":true},"key1":12}
// How is it sorted ??
// trying to get a int from a JSONObject: OK
int value=0;
try {
value = obj.getInt("key1");
}
catch(JSONException e) {
e.getCause();
}
println(value);
//prints: 12
// trying to get a JSONObject from a bigger one: OK
JSONObject getObj2 = new JSONObject();
try {
getObj2 = obj.getJSONObject("obj2");
}
catch(JSONException e) {
e.getCause();
}
println(getObj2);
// prints: {"key4":"FFFFFF","key3":true}
// creating a JSONArray of JSONObjects: OK
arr = new JSONArray();
arr.put(obj);
arr.put(obj2);
arr.put(getObj2);
println(arr);
// prints: [{"key2":"value","obj2":{"key4":"FFFFFF","key3":true},"key1":12},{"key4":"FFFFFF","key3":true},{"key4":"FFFFFF","key3":true}]

I also modified the reading_yahoo_weather, had to change the url since it seems yahoo weather api does not directly output JSON anymore, had to do this:

// Accessing the weather service
String BASE_URL = "http://query.yahooapis.com/v1/public/yql?q=";
String WOEID = "3015";
// Get the JSON formatted response
String response = loadStrings( BASE_URL +"select%20item%20from%20weather.forecast%20where%20location%3D\""+ WOEID +"\"&format=json" )[0];

So it becomes:

import org.json.*;
void setup() {
// Accessing the weather service
String BASE_URL = "http://query.yahooapis.com/v1/public/yql?q=";
String WOEID = "3015";
// Get the JSON formatted response
String response = loadStrings( BASE_URL +"select%20item%20from%20weather.forecast%20where%20location%3D\""+ WOEID +"\"&format=json" )[0];
// Make sure we got a response.
if ( response != null ) {
// Initialize the JSONObject for the response
JSONObject root = new JSONObject();
try {
root = new JSONObject( response );
}
catch(JSONException e) {
e.getCause();
}
println(root); // OK
// Get the "condition" JSONObject
JSONObject condition = new JSONObject();
try {
condition = root.getJSONObject("condition");
}
catch(JSONException e) {
e.getCause();
}
//print the JSONObject condition: FAIL
println(condition); // prints: {};
// Get the "temperature" value from the condition object
int temperature=0;
try {
temperature = condition.getInt("temp");
}
catch(JSONException e) {
e.getCause();
}
// Print the temperature: FAIL
println( temperature ); // prints: 0;
}
}
void draw() {
}

-> trying to get a JSONObject from a bigger one: FAIL

-> trying to get a int from a JSONObject: FAIL

Makio135
http://makio135.com/

Makio135

Re: JSON4processing Unhandled exception type JSON Exception

11 months ago

I did a clean Github repo for JSON4Processing with examples using the try/catch pattern: https://github.com/MAKIO135/JSON-processing

Makio135
http://makio135.com/

Makio135

Re: JSON4processing Unhandled exception type JSON Exception depend on OS [update]

11 months ago

From downloading the cleaned 1.3.1 repo i did, I found a strange behavior of the library depending with the os:
- on Windows7: you have to use the try/catch pattern or you'll get the Unhandled exception type JSON Exception
- on Mac OS10.8: you must NOT use the try/catch pattern or you'll get an " Unreachable catch block for JSONException. This exception is never thrown from the try statement body" on line catch(JSONException e){}

Both with Processing 1.5.1., any idea on how to get the same behavior on both?

Makio135
http://makio135.com/

lasko25

Re: JSON4processing Unhandled exception type JSON Exception depend on OS [update]

11 months ago

Just want to add here, I just started using the library today.

I was having the same JSONExeption error with this code:

JSONObject root = new JSONObject( response );

JSONArray datastreams = root.getJSONArray("datastreams");

println(datastreams);

println(" ");

println(datastreams.getJSONObject(0).getString("current_value"));

^ This was the offending line.

I changed that line to this:

try{

println(datastreams.getJSONObject(0).getString("current_value"));

}

catch(JSONException e){

e.getCause();

}

And it worked perfectly fine.

Makio135

Re: JSON4processing Unhandled exception type JSON Exception depend on OS [update]

11 months ago

Hey lasko25,
what system are you working on?

Makio135
http://makio135.com/

a__g

Re: JSON4processing Unhandled exception type JSON Exception depend on OS [update]

10 months ago

Dudes, I think I found it. There was a remaining exception being thrown by the "getJSONObject()" inside the JSONArray class. I'm pushing the updated version to github now, please try it.

Makio, I still have no clue as to why your code behaves differently depending on the OS.

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