B4J Question Little help needed with javaobject

[Arie van Wingerden]

Running the following code:

'Non-UI application (console / server application)
#Region Project Attributes
    #CommandLineArgs:
    #MergeLibraries: True
#End Region

#If JAVA
import java.util.*;
public Map<String, String> GetEnvMap() {
    return System.getenv();
}
#End If

Sub Process_Globals
    Private jo As JavaObject
End Sub

Sub AppStart (Args() As String)
    Log("Before")

    Private envMap As Map = jo.RunMethod("GetEnvMap", Null)
    Log("After")
    For Each k As String In envMap.Keys
        Log(k+"="+ envMap.Get(k) )
    Next
End Sub

'Return true to allow the default exceptions handler to handle the uncaught exception.
Sub Application_Error (Error As Exception, StackTrace As String) As Boolean
    Return True
End Sub

gives me:

Waiting for debugger to connect...
Program started.
Before
Error occurred on line: 21 (Main)
java.lang.RuntimeException: Object should first be initialized (JavaObject).
at anywheresoftware.b4a.AbsObjectWrapper.getObject(AbsObjectWrapper.java:32)
at anywheresoftware.b4j.object.JavaObject.getCurrentClass(JavaObject.java:259)
at anywheresoftware.b4j.object.JavaObject.RunMethod(JavaObject.java:119)
at b4j.example.main._appstart(main.java:80)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:632)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:234)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:167)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:91)
at anywheresoftware.b4a.shell.ShellBA.raiseEvent2(ShellBA.java:98)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:78)
at b4j.example.main.main(main.java:30)
Program terminated (StartMessageLoop was not called).

I guess that I have to instantiate variable "jo" first, but my knowledge of both java and b4j is still very limited ...
Thanks for any help ...

 

[EnriqueGonzalez]

Write

Sub asjo as javaobject
Return me
End sub.

And use it like asjo.runmethod...

 

[EnriqueGonzalez]

And there is a shortcut for what you are trying to get.

GetSystemProperty(...

 

[Arie van Wingerden]

Hi Enrique,

I tried to accomplish what you said in the first answer, but it does not work.
Would you be so kind to post my complete code with your suggested changes please?

As for GetSystemProperty I get many hits in the forum, but is there a complete reference for this command? It is not in the basic language manual ...

 

[EnriqueGonzalez]

There you have it, but it is not like you thought, the map that returns your inline java doesnt return a compatible b4xMap. so some shortcuts had to be taken.

 

[Erel]

It will be easier to help you if you tell us what you are trying to solve.

If you are trying to get an environment variable then use GetEnvironmentVariable:

 

[Arie van Wingerden]

It will be easier to help you if you tell us what you are trying to solve.

If you are trying to get an environment variable then use GetEnvironmentVariable:

View attachment 96524

I tried to get a map containing keys holding all EnvVar names and values their respective values.

 

[Arie van Wingerden]

There you have it, but it is not like you thought, the map that returns your inline java doesnt return a compatible b4xMap. so some shortcuts had to be taken.

Thank you very much!
This does exactly what I intended and I understand what you are doing.
.
So, I understand that it is not possible to map a Java Map directly to a B4J Map.?

 

[EnriqueGonzalez]

not possible to map a Java Map directly to a B4J Map.?

It is possible. But not this particular map as it inherits a non compatible form of map.