Java Infinite LiveCode

[livecodeali]

Paul McClernan has had trouble getting the examples in my blog (https://livecode.com/livecode-9-0-dp-6- ... ment-36573) to work, so here is a thread for ironing out any issues.

Firstly, here is a single library that should add the GetBatteryPercentage function to the message path, so it is usable on Android:

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library com.livecode.library.androidbattery

use com.livecode.foreign
use com.livecode.java

metadata title is "Android Battery Library"
metadata author is "LiveCode"
metadata version is "1.0.0"

foreign handler ClassForName(in pClass as JString) returns JObject binds to "java:java.lang.Class>forName(Ljava/lang/String;)Ljava/lang/Class;!static"
foreign handler GetCurrentApplicationMethod(in pActivityThread as JObject, in pMethod as JString, in pParams as optional JObject) returns JObject binds to "java:java.lang.Class>getMethod(Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;"
foreign handler MethodInvoke(in pMethod as JObject, in pInstance as optional JObject, in pParams as optional JObject) returns JObject binds to "java:java.lang.reflect.Method>invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;"

foreign handler GetIntentFilter(in pAction as JString) returns JObject binds to "java:android.content.IntentFilter>new(Ljava/lang/String;)"
foreign handler ApplicationRegisterReceiver(in pContext as JObject, in pObj as optional JObject, in pFilter as JObject) returns JObject binds to "java:android.content.Context>registerReceiver(Landroid/content/BroadcastReceiver;Landroid/content/IntentFilter;)Landroid/content/Intent;"

foreign handler GetIntentValueInt(in pIntent as JObject, in pWhich as JString, in pDefault as CInt) returns CInt binds to "java:android.content.Intent>getIntExtra(Ljava/lang/String;I)I"

public handler GetBatteryPercentage() returns Number
    unsafe 
        variable tClass as JObject
        put ClassForName(StringToJString("android.app.ActivityThread")) into tClass

        variable tMethod as JObject
        put GetCurrentApplicationMethod(tClass, StringToJString("currentApplication"), nothing) into tMethod
                
         variable tContext as JObject
         put MethodInvoke(tMethod, nothing, nothing) into tContext
                 
         variable tFilter as JObject
         put GetIntentFilter(StringToJString("android.intent.action.BATTERY_CHANGED")) into tFilter

         variable tIntent as JObject
         put ApplicationRegisterReceiver(tContext, nothing, tFilter) into tIntent
                 
        variable tLevel as Integer
        put GetIntentValueInt(tIntent, StringToJString("level"), -1) into tLevel

        variable tScale as Integer
        put GetIntentValueInt(tIntent, StringToJString("scale"), -1) into tScale

        return tLevel / tScale * 100    
    end unsafe
end handler

end library

[livecodeali]

Regarding the error using the Java BigInteger class, the only reason I can think of why it wouldn't work would be that the value of JAVA_HOME was not set correctly (note the blurb about launching LC from the command line to make it work at the moment).

We have scheduled an item to be done asap which is to make the errors from LCB more helpful in the IDE, but in the meantime, try putting it in the script of a button:

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on mouseUp
   try
      AddBigIntegers("12345","12345")
   catch tError
      put tError
   end try
end mouseUp

this will hopefully make the error clearer

[PaulDaMacMan]

I didn't realize that setting $JAVA_HOME is not persistent across restarts.

So I just remembered the example you gave in the comments wouldn't compile until I changed

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put BigInteger_add(tLeftBigInt, tRightBigInt) into tSumBigInt

to

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put _JNI_BigInteger_add(tLeftBigInt, tRightBigInt) into tSumBigInt

Now I'm getting this as a result of button with the try / catch :
885,3,1
896,3,1
573,3,1,AddBigIntegers

I really need to install an editor with line numbers (new laptop).

[PaulDaMacMan]

As for the Android code, I removed my previous build and I pasted your code into a new lcb file, recompiled the lib extension, rebuilt my apk, and reinstalled.

GetBatteryPercentage() still returns nothing on my phone.
My test app has a button and a field:

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on mouseUp
  get GetBatteryPercentage()
  put it into tBatPercent
  put tBatPercent into field 1
  Answer "Percentage: " & tBatPercent
end mouseUp

[PaulDaMacMan]

Did the whole thing over on my work computer and changed the test app code to this:

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on mouseUp
   try
      get GetBatteryPercentage() 
   catch tError
      put tError into fld "Output"
   end try
   put GetBatteryPercentage() after fld "Output"
   answer "hello" & GetBatteryPercentage()
end mouseUp

Pushing the button on my phone the field Output field contains two lines:

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219,3,11,GetBatteryPercentage
223,3,11

[PaulDaMacMan]

Just to be sure it's not some unique problem with my setup, I made new basic app with one (custom LCB made) widget and a hello world button which built and worked fine on my phone.
I was testing on Mac OS X 10.10.5 (laptop) Mac OS X 10.9.5 (workstation)

[livecodeali]

Thanks for testing - I'll try and work out what's going on! They both work for me here, although I don't have a device at hand to test right now, just simulator.

[livecodeali]

OK,

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219,3,11,GetBatteryPercentage
223,3,11

means the function was not found, i.e. the library is not loaded in the standalone. You could confirm this by checking the loadedExtensions in the standalone. I suspect there is just a problem with including the module. Note it will not be included automatically, the library needs to be installed and manually selected in the inclusions pane.

[livecodeali]

It seems that

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573,3,1,AddBigIntegers

also happens when the library is not loaded. The other numbers are slightly bizarre, in particular error 896 doesn't exist...

(ps you can make sense of the error code using

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put line 573 of the scriptexecutionerrors

)

[LCMark]

Hmmmm the following error:

Now I'm getting this as a result of button with the try / catch :
885,3,1
896,3,1
573,3,1,AddBigIntegers

Is TypeError (one of the arguments is of the wrong type) and TooFewArguments it appears - which is a bit odd as I'm sure it should either be one or the other based on the current implementation.

The error:

573,3,1,AddBigIntegers

Means that the handler isn't found.

[LCMark]

So - looking into this - the error is TooFewArguments (the TypeError is an error in the engine code which is throwing the error when it shouldn't).

The problem with the Big integer example above is that it calling AddBigINtegers like a command, which means ("12345", "12345") is treated as a single argument:

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on mouseUp
  try
    get AddBigIntegers("12345", "12345") -- function form
    AddBigIntegers "12345", "12345" -- command form
  catch tError
    ...
  end try
end mouseUp

[PaulDaMacMan]

Forgot to follow up on this...
So the Java BigInt code works on Mac, but only as long as I remember to launch LC IDE from the terminal AND set the variable $JAVA_HOME to the output of shell("/usr/libexec/java_home"). These two things must be done EVERY TIME you want to use the Java library, if you don't do both before calling the function it won't work! This is kind of a PITA so I might make an AppleScript or something to automate it.

[PaulDaMacMan]

Also for anyone else having problems, after changing the standalone General tab's inclusion setting (radio button) to "Select inclusions..." and then manually selecting these FFI libraries in the inclusions tab, both the battery level and java bigint functions worked as expected in my Android standalone (on my phone running Android 7.0).