B4J Question jGauges javaobject inline casting not working

[Chris2]

I'm getting an error when using inline casting to set the parameter type for a javaobject call to jGauges.

For example, "setMinValue" & "setMaxValue" want a double. But adding to the jGauges example app:

Sub AppStart (Form1 As Form, Args() As String)
    :
    :
    :
    SetMaxMin
    
End Sub


Private Sub SetMaxMin

    Dim joGauge As JavaObject = Gauge1
    
    Dim minVal As Float = 0
    Dim maxVal As Float = 100

    joGauge.RunMethod("setMinValue", Array(minVal.As(Double)))
    joGauge.RunMethod("setMaxValue", Array(maxVal.As(Double)))
    
End Sub

Generates the error:

java.lang.RuntimeException: Method: setMinValue not matched.
    at anywheresoftware.b4j.object.JavaObject.RunMethod(JavaObject.java:130)
    at b4j.example.main._setmaxmin(main.java:202)
    at b4j.example.main._appstart(main.java:128)
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
    at java.base/java.lang.reflect.Method.invoke(Method.java:577)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:629)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:237)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:167)
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
    at java.base/java.lang.reflect.Method.invoke(Method.java:577)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:111)
    at anywheresoftware.b4a.shell.ShellBA.raiseEvent2(ShellBA.java:100)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:98)
    at b4j.example.main.start(main.java:38)
    at [email protected]/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:847)
    at [email protected]/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:484)
    at [email protected]/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:457)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
    at [email protected]/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:456)
    at [email protected]/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
    at [email protected]/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at [email protected]/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
    at java.base/java.lang.Thread.run(Thread.java:833)

But using the following instead works successfully:

Private Sub SetMaxMin
    Dim joGauge As JavaObject = Gauge1
    
    Dim minVal As Float = 0
    Dim maxVal As Float = 100
    
    Dim minDouble As Double = minVal
    Dim maxDouble As Double = maxVal
    joGauge.RunMethod("setMinValue", Array(minDouble))
    joGauge.RunMethod("setMaxValue", Array(maxDouble))
    
End Sub

Am I doing something incorrectly with the inline casting?

 

[DonManfred]

Gauge1 is a wrapperobject above the Gauge itself.

So you probably have to get the native Gauge from it first.

joGauge.RunMethod("getObject", Null)

it returns another JavaObject. Hopefully the Gauge.
Call setMinValue on this now.

 

[Johan Schoeman]

The min and max values must be "double". When passing a float it will say the signature is not matched. Not sure why the casting from float to double is not working

 

[Chris2]

Thanks for the help, but

joGauge.RunMethod("getObject", Null)

errors with:

java.lang.RuntimeException: Method: getObject not found in: eu.hansolo.medusa.Gauge

Also, if I wasn't already getting to the gauge itself then casting the variables to Doubles before doing the joGauge.RunMethod wouldn't work would it?
As in the second set of code in my first post, which already works OK...

Dim minDouble As Double = minVal
    Dim maxDouble As Double = maxVal
    joGauge.RunMethod("setMinValue", Array(minDouble))
    joGauge.RunMethod("setMaxValue", Array(maxDouble))

 

[Chris2]

The min and max values must be "double". When passing a float it will say the signature is not matched. Not sure why the casting from float to double is not working

Exactly. My question is, why isn't the inline casting working?

 

[Johan Schoeman]

Exactly. My question is, why isn't the inline casting working?

Try by making the min 0.0 and max 100.0 and see if the casting then works. Just a guess..

 

[DonManfred]

getObject not found in: eu.hansolo.medusa.Gauge

ok. that indicates you are at the correct point already. At least i guess it.
So the call to setMinValue is not correct it seems.

 

[Chris2]

Try by making the min 0.0 and max 100.0 and see if the casting then works. Just a guess..

Thanks for the suggestion, but this gives the same error.

 

[Chris2]

So the call to setMinValue is not correct it seems.

But it works OK if I cast the value to a double before using it:

Dim minVal As Float = 0

'works
Dim minDouble As Double = minVal
joGauge.RunMethod("setMinValue", Array(minDouble))

'fails, why?
joGauge.RunMethod("setMinValue", Array(minVal.As(Double)))

 

[DonManfred]

'works Dim minDouble As Double = minVal

then use it like this

 

[agraham]

Erel would have to explain why but As() doesn't necessarily always do what you might expect. In this case it is ignored in the compiled java which just casts the float value to Object for inclusion in the parameter array,

 //BA.debugLineNum = 72;BA.debugLine="joGauge.RunMethod(\"setMinValue\", Array(minVal.As(Double)))";
_jogauge.RunMethod("setMinValue",new Object[]{(Object)((_minval))});

 

[Erel]

Double is treated specially by the compiler. It lets the Java compiler make the casting when needed to save unrequired casting.

It is a bug that As(Double) doesn't work.

 

[Chris2]

Thanks everyone.
It's nice to know for sure that it wasn't me using inline casting incorrectly .

 

[agraham]

It is a bug that As(Double) doesn't work.

And there was me assuming that Erel was using some arcane divination beyond my ability to understand when it was a bug all along