Java Question creating a simple library

[rbirago]

On YouTube I've found a simple tutorial to build a B4A library and I've followed step-by-step all the instructions.
This is Java code:

package anywheresoftware.b4a.sample;

import anywheresoftware.b4a.BA.ShortName;

@ShortName("FirstLib2")
public class FirstLib2 {
    /**
     * test wrapper semplice B4a
     * @param x : numero da moltiplicare
     * @return : x * 2
     */
    public int multiply(int x) {
        return x * 2;
    }
}

As of instructions I've referenced these jars:
Core.jar
B4AShared.jar
android.jar

The JDK version is 1.8
I've created without problems FirstLib2.jar and FirstLib2.xml in AddLibraries directory.
Then I created test_FirstLib2:

#Region  Project Attributes
    #ApplicationLabel: B4A Example
    #VersionCode: 1
    #VersionName:
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: unspecified
    #CanInstallToExternalStorage: False
#End Region

#Region  Activity Attributes
    #FullScreen: False
    #IncludeTitle: True
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.
    Dim fl As FirstLib2
End Sub

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.

End Sub

Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:
    'Activity.LoadLayout("Layout1")
    Log(fl.multiply(10))
End Sub

Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Running test_FirstLib2 it gives me this error:

B4A version: 6.00
Parsing code. (0.00s)
Compiling code. (0.05s)
Compiling layouts code. (0.01s)
Organizing libraries. (0.01s)
Generating R file. (1.43s)
Compiling debugger engine code. (2.31s)
Compiling generated Java code. (2.72s)
Convert byte code - optimized dex. Error
UNEXPECTED TOP-LEVEL EXCEPTION:
com.android.dx.cf.iface.ParseException: bad class file magic (cafebabe) or version (0034.0000)
at com.android.dx.cf.direct.DirectClassFile.parse0(DirectClassFile.java:472)
at com.android.dx.cf.direct.DirectClassFile.parse(DirectClassFile.java:406)
at com.android.dx.cf.direct.DirectClassFile.parseToInterfacesIfNecessary(DirectClassFile.java:388)
at com.android.dx.cf.direct.DirectClassFile.getMagic(DirectClassFile.java:251)
at com.android.dx.command.dexer.Main.processClass(Main.java:598)
at com.android.dx.command.dexer.Main.processFileBytes(Main.java:570)
at com.android.dx.command.dexer.Main.access$2(Main.java:546)
at com.android.dx.command.dexer.Main$2.processFileBytes(Main.java:514)
at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:284)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:166)
at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:144)
at com.android.dx.command.dexer.Main.processOne(Main.java:537)
at com.android.dx.command.dexer.Main.processAllFiles(Main.java:449)
at com.android.dx.command.dexer.Main.runMonoDex(Main.java:236)
at com.android.dx.command.dexer.Main.run(Main.java:206)
at com.android.dx.command.dexer.Main.main(Main.java:179)
at com.android.dx.command.Main.main(Main.java:103)
...while parsing anywheresoftware/b4a/sample/FirstLib2.class
1 error; aborting

Any suggestion?

thank you
Roberto

 

[Erel]

Try to compile it with SLC: https://www.b4x.com/android/forum/threads/29918/#content