Android Question Calling HTTPJOB from a class

MotoMusher · Sep 24, 2015

Maybe it's been a long day, but I am trying to call HTTPJOB from a class since this collection of Subs gets called from multiple activities. It works fine from an activity passing "ME" as the target with jobdone in the activity. I get a null object error from the class immediately when I initialize, which makes sense. So, I put my jobdone event in Main, and pass Main as the target object and that gives me null object errors as well.

java.lang.NullPointerException: Attempt to read from field 'anywheresoftware.b4a.BALayout anywheresoftware.b4a.BA.vg' on a null object reference

Any ideas?

Roycefer · Sep 24, 2015

Try putting JobDone() inside the class and have your class raise an event using CallSubDelayed() when it has processed JobDone().

An example:

B4X:

'ExampleClass
#Event: RequestFinished

Sub Class_Globals
    Private cbObj as Object
    Private cbEN as String
End Sub

Sub Initialize(callbackModule as Object, callbackEventName as String)
    cbObj = callbackObj
    cbEN = callbackEventName
End Sub

Sub StartRequest
    Dim hj as HttpJob
    hj.Initialize("hj", Me)
    hj.Download("http://b4x.com/android/forum/threads/calling-httpjob-from-a-class.58672/")
End Sub

Sub JobDone(Job as HttpJob)
    CallSubDelayed(cbObj, cbEN & "_RequestFinished")
    Job.Release
End Sub

Then, in some Activity:

B4X:

Sub StartHere
    Dim ec as ExampleClass
    ec.Initialize(Me, "ec")
    ec.StartRequest
End Sub

Sub ec_RequestFinished
    Log("RequestFinished")
End Sub

FrankDev · Sep 24, 2015

Roycefer said:

Try putting JobDone() inside the class and have your class raise an event using CallSubDelayed() when it has processed JobDone().

An example:

B4X:

'ExampleClass
#Event: RequestFinished

Sub Class_Globals
    Private cbObj as Object
    Private cbEN as String
    Private cbURL as String   'new
End Sub

Sub Initialize(callbackModule as Object, callbackEventName as String, URL as String)   'new
    cbObj = callbackObj
    cbEN = callbackEventName
    cbURL = URL 'new
End Sub

Sub StartRequest
    Dim hj as HttpJob
    hj.Initialize("hj", Me)
    hj.Download(cbURL) 'new
End Sub

Sub JobDone(Job as HttpJob)
    dim http_answer as String  'new
    http_answer =Job.GetString 'new
    CallSubDelayed2(cbObj, cbEN & "_RequestFinished",http_answer)  'new
    Job.Release
End Sub

Then, in some Activity:

B4X:

Sub StartHere
    Dim ec as ExampleClass
    ec.Initialize(Me, "ec","http://b4x.com/android/forum/threads/calling-httpjob-from-a-class.58672/") 'new
    ec.StartRequest
End Sub

Sub ec_RequestFinished(http_answer  as String) 'new
    Log("RequestFinished")
End Sub

hi

is this a possibel way to use different url's
what about if the Server do not respond ?

regards Frank

Roycefer · Sep 24, 2015

You can do this:

B4X:

#Event: RequestError(errorMessage as String)
'Add this new event annotation to the top of the class

Sub StartRequest(url as String)   'pass a URL at run-time
    Dim hj as HttpJob
    hj.Initialize("hj", Me)
    Try
        hj.Download(url)
    Catch   'If the server doesn't respond, hj.Download will throw an Exception
        CallSubDelayed2(cbObj, cbEN & "_RequestError", LastException.Message)
    End Try
End Sub

Sub JobDone(Job as HttpJob)
    If Not(Job.Success) Then    'Also raise the error event here
        CallSubDelayed2(cbObj, cbEN & "_RequestError", Job.ErrorMessage)
    Else
        'Normal operation
    End If
    Job.Release
End Sub

MotoMusher · Sep 26, 2015

I found the problem. Thanks for the responses.

Issue was that I was calling the class without initializing first from the activity. Class processed multiple subs that are strung together fine, but had no value for ME to pass to httpjob.

Android Question Calling HTTPJOB from a class

MotoMusher

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Roycefer

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FrankDev

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MotoMusher

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