Android Question Basics -- Strings, Objects and Types

Steve Piehl · Nov 27, 2016

I have been playing with this for quite awhile and not sure how to use the CallSubDelayedPlus2 routine. I have loaded the CallSubUtils class module and I am attempting to call a subroutine in the same module I am in (main).

I have already tried to review the tutorial on variables and objects and I am just not understanding something. I don't understand enough about Objects versus Strings. How do you convert from object to a string and vice versa?

My original subroutine "SendJobToServer" was setup to receive an arg as a "String" arg...not an "Object". The CallSubDelayedPlus2 routine requires that args be sent as Objects. I changed the arg to look for an object...but that doesn't seem to work. In the code snippet below, I attempt to pass the String arg "StatusUpdate" as an object to be used in the subroutine. Also I need this arg "JobName" to be a string. Do I have to use stringbuilder to get around the need for a string after passing it as an object? How do I pass it as an object?

B4X:

Sub SendJobtoServer (JobName As Object)
    Log("SendJobtoServer, Job= "& JobName)
    Dim j As HttpJob
    j.Initialize(JobName, Me)
    j.Download(ServerLink & "/" & JobName)
    If JobName = "StatusUpdate" Then 
        ProgressDialogShow("Updating System Status...")
    Else
        ProgressDialogShow("Downloading report...")
    End If
End Sub

Sub SetSystem Status
    ...
    Dim Job2Send As Object
    Job2Send="StatusUpdate"
    Starter.csu.CallSubDelayedPlus2(Me,"SendJobtoServer",2000,Job2Send) '<---error object
End Sub

Any help is appreciated.

Erel · Nov 28, 2016

B4X:

Starter.csu.CallSubDelayedPlus2(Me, "SendJobTo_Server", 2000, Array ("StatusUpdate")) 

Sub SendJobTo_Server (Name As String) 'tip: add an underscore to prevent the obfuscator from obfuscating the sub name
...
End Sub

Steve Piehl · Nov 28, 2016

Erel -- thanks for your reply. I made the changes you suggested.

I am still generating an error...now it appears that I can pass the variable to the SendJobTo_Server routine...but this routine is generating a similar error on the j.initialize line.

B4X:

Sub SendJobTo_Server (JobName As String)

    Log("SendJobtoServer, Job= "& JobName)
    Dim j As HttpJob
    j.Initialize(JobName, Me)  '<---ERROR occurs here now (line 113)
    j.Download(ServerLink & "/" & JobName)
    If JobName = "StatusUpdate" Then
        ProgressDialogShow("Updating System Status...")
    Else
        ProgressDialogShow("Downloading report...")
    End If
End Sub

Here is the output from the debug log:

B4X:

SendJobtoServer, Job= [Ljava.lang.Object;@6eb6977
Error occurred on line: 113 (Main)
java.lang.IllegalArgumentException: method anywheresoftware.b4a.samples.httputils2.httpjob._initialize argument 2 has type java.lang.String, got java.lang.Object[]
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runVoidMethod(Shell.java:753)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:343)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:247)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:134)
    at anywheresoftware.b4a.BA$2.run(BA.java:328)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:158)
    at android.app.ActivityThread.main(ActivityThread.java:7224)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

KMatle · Nov 29, 2016

Clear: You send an array. Jobname must be a string. So just convert it back to a string...

DonManfred · Nov 29, 2016

B4X:

    Starter.csu.CallSubDelayedPlus3(Me, "SendJobTo_Server", 2000, Array As String("StatusUpdate"))

Sub SendJobTo_Server (param() As String)
    Dim jobname As String = param(0)
        Log("SendJobtoServer, Job= "& jobname)
    Dim j As HttpJob
    j.Initialize(jobname, Me)  '<---ERROR occurs here now (line 113): occurs no longer
    'j.Download(ServerLink & "/" & JobName)
    'If JobName = "StatusUpdate" Then
    '    ProgressDialogShow("Updating System Status...")
    'Else
    '    ProgressDialogShow("Downloading report...")
    'End If
End Sub

And the method you need to add to the CallSubUtils Class

B4X:

Public Sub CallSubDelayedPlus3(Module As Object, SubName As String, Delay As Int, Arg() As String)
    PlusImpl(Module, SubName, Delay, Arg, True)
End Sub

** Service (starter) Create **
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
** Activity (main) Resume **
SendJobtoServer, Job= StatusUpdate
** Activity (main) Pause, UserClosed = false **
** Activity (main) Resume **

Erel · Nov 29, 2016

My code was wrong. See the tutorial: https://www.b4x.com/android/forum/threads/b4x-callsubplus-callsub-with-explicit-delay.60877/#content

It should be:

B4X:

Starter.csu.CallSubDelayedPlus2(Me, "SendJobTo_Server", 2000, Array ("StatusUpdate")) 

Sub SendJobTo_Server (Args() As Object) 'tip: add an underscore to prevent the obfuscator from obfuscating the sub name
 Dim Name As String = Args(0)
End Sub

Steve Piehl · Nov 29, 2016

Thank you to everyone for your replies. I am beginning to understand how to convert objects to strings and vice versa.

I was missing the idea that you can pass an arg to a subroutine as an object and then re-define that object/item to another datatype on-the-fly. This is very useful information. Thanks again!

Android Question Basics -- Strings, Objects and Types

Steve Piehl

Member

Erel

B4X founder

Steve Piehl

Member

KMatle

Expert

DonManfred

Expert

Erel

B4X founder

Steve Piehl

Member

Similar Threads

Android Question Basics -- Strings, Objects and Types

Steve Piehl

Member

Erel

B4X founder

Steve Piehl

Member

KMatle

Expert

DonManfred

Expert

Erel

B4X founder

Steve Piehl

Member

Similar Threads

Privacy & Transparency

Privacy & Transparency