Android Question Parse JSON

[AlpVir]

In the post #33 https://www.b4x.com/android/forum/threads/android-json-tutorial.6923/page-2
the user "sioconcept" wrote

Is there a limit size of the JSON string?

and Erel answered

There is no hard limit.

However I tried to parse the 18 MB "c.json" file and got the error

java.lang.OutOfMemoryError: OutOfMemoryError thrown while trying to throw OutOfMemoryError; no stack available

This is the simple code

Dim List1 As List
    Dim JSON As JSONParser
    JSON.Initialize(File.ReadString(File.DirAssets, "c.json"))
    List1.Initialize
    List1 = JSON.NextArray
    Dim M As Map
    M = List1.Get(0)
    Dim loc As Map
    loc = M.Get("id")
    For i = 0 To 50        ' loc.Size - 1
        Dim Longitude     As Double
        Dim Latitude     As Double
        Dim name         As String
        Longitude = loc.Get ("lon")
        Latitude = loc.Get ("lat")
        name = loc.Get ("name")
        Log(name & "  " & Latitude & "  " & Longitude)
    Next

and this is a very very small part of the "c.json" file

{
"id": 3177841,
"coord": {
"lon": 9.66826,
"lat": 45.358768
},
"country": "IT",
"geoname": {
"cl": "P",
"code": "PPLA3",
"parent": 6540640
},
"name": "Crema",
"stat": {
"level": 1.0,
"population": 32981
},
"stations": [
{
"id": 5794,
"dist": 34,
"kf": 1
},
{
"id": 5800,
"dist": 31,
"kf": 1
},
{
"id": 5820,
"dist": 40,
"kf": 1
},
{
"id": 8977,
"dist": 0,
"kf": 1
},
{
"id": 9552,
"dist": 13,
"kf": 1
},
{
"id": 9798,
"dist": 34,
"kf": 1
},
{
"id": 10222,
"dist": 39,
"kf": 1
},
{
"id": 10368,
"dist": 39,
"kf": 1
},
{
"id": 10799,
"dist": 44,
"kf": 1
},
{
"id": 28814,
"dist": 42,
"kf": 1
},
{
"id": 29222,
"dist": 0,
"kf": 1
},
{
"id": 32018,
"dist": 18,
"kf": 1
},
{
"id": 32561,
"dist": 39,
"kf": 1
},
{
"id": 34103,
"dist": 43,
"kf": 1
},
{
"id": 35260,
"dist": 15,
"kf": 1
},
{
"id": 35663,
"dist": 39,
"kf": 1
}
],
"zoom": 10
},
{
"id": 3177924,
"coord": {
"lon": 8.18172,
"lat": 45.57386
},
"country": "IT",
"geoname": {
"cl": "P",
"code": "PPLA3",
"parent": 6540883
},
"langs": [
{
"de": "Cossato"
},
{
"en": "Cossato"
},
{
"eo": "Cossato"
},
{
"fr": "Cossato"
},
{
"it": "Cossato"
},
{
"link": "http://en.wikipedia.org/wiki/Cossato"
},
{
"nap": "Cossato"
},
{
"nl": "Cossato"
},
{
"pl": "Cossato"
},
{
"pt": "Cossato"
}
],
"name": "Cossato",
"stat": {
"level": 1.0,
"population": 15266
},
"stations": [
{
"id": 5792,
"dist": 43,
"kf": 1
},
{
"id": 30106,
"dist": 47,
"kf": 1
},
{
"id": 30420,
"dist": 48,
"kf": 1
},
{
"id": 32877,
"dist": 48,
"kf": 1
},
{
"id": 33359,
"dist": 36,
"kf": 1
},
{
"id": 33573,
"dist": 47,
"kf": 1
},
{
"id": 34361,
"dist": 27,
"kf": 1
},
{
"id": 34492,
"dist": 46,
"kf": 1
},
{
"id": 35332,
"dist": 32,
"kf": 1
},
{
"id": 36136,
"dist": 35,
"kf": 1
}
],
"zoom": 11
},

How do you explain all this?
Thanks for the attention !

 

[Peter Simpson]

I believe that this error is to do with the java heap memory capacity setting and nothing to do with JSON or the list.

You need to allocate more memory to java by setting your Windows enviroment variables for Xmx Xms. If you do a google search for java Xmx Xms heap size, you will find clear instructions on how to increase it to let say 4GB which is what mine is set to.

Also search for Xincgc, that may help you too.

That's my guess anyway, but I could be wrong...

Enjoy...

 

[AlpVir]

Thank you. My final goal is to turn these json files (even 28 MB !) into db sqlite. I will try to transform them with other software tools.

 

[Peter Simpson]

By the way you can easily tell if you have implemented Xmx and Xms correctly through Windows, as every time you run any B4J project even a blank project, you will see the following line appear in the logs when you stop the project.

Spoiler: Log in B4J

Picked up _JAVA_OPTIONS: -Xmx2g -Xms2g

Enjoy...

 

[Erel]

With "no hard limit" I meant that the only limit is the available memory.

It should be simple to convert your json files to SQLite dbs with B4J.