B4J Question How to use an Additional JAR

Brian Dean · Jan 16, 2023

This is my first attempt to use an additional jar. I am using what we call in the UK a "monkey see; monkey do" approach - trying to copy what others seem to have done, not necessarily understanding what I am doing. Helped by posts on this forum I have constructed a test using the zip4J library that I have found at this link. Here is my complete program :

B4X:

#Region Project Attributes
    #MainFormWidth: 600
    #MainFormHeight: 600
    #AdditionalJar: zip4j-2.11.1.jar
#End Region

Sub Process_Globals
    Private MainForm As Form
    Private Button1 As B4XView            
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    MainForm = Form1
    MainForm.RootPane.LoadLayout("Layout1")
    MainForm.Show
End Sub

Sub Button1_Click
    zip("E:/Temp/Waffle.jpg", "E:/Temp/Waffle.zip")            ' Test sample
End Sub

Public Sub zip(filename As String, zipFile As String)
    Dim zipper As JavaObject
    Dim constants As JavaObject
    zipper.InitializeNewInstance("net.lingala.zip4j.core.ZipFile", Array(zipFile))
    constants.InitializeStatic("net.lingala.zip4j.util.Zip4jConstants")   
    zipper.RunMethod("addFile", Array(filename))   
End Sub

I am getting the error :

java.lang.ClassNotFoundException: net.lingala$zip4j$core$ZipFile

What have I missed?

EnriqueGonzalez · Jan 16, 2023

Brian Dean said:
net.lingala.zip4j

You are still missing the last part :
net.lingala.zip4j.ZipFile
what you had extra was the core part

you usually use the last line on this image:

Brian Dean said:
Array As String(zipFile)

dont use array as string, this is actually creating a constructor and passing parameters it is not passing the parameters directly so even if the method requires an String, you want to use a simple Array

if it still fails, share the .jar file you are using, you may be even using a different version

Daestrum · Jan 16, 2023

It looks like

B4X:

zipper.InitializeNewInstance("net.lingala.zip4j.core.ZipFile", Array(zipFile))

should maybe be

B4X:

zipper.InitializeNewInstance("net.lingala.zip4j.ZipFile", Array As String(zipFile))

I would think it will pull in the constants itself so no need for the IntializeStatic line

But.... I could be wrong.

I did edit it after you must have looked at it as I realized I had left off the Zipfile at the end of the line.

Brian Dean · Jan 16, 2023

Thanks for your suggestion. I changed line 25 in the original post to this :

B4X:

    zipper.InitializeNewInstance("net.lingala.zip4j", Array As String(zipFile))

The error that I get now is ...

B4X:

java.lang.ClassNotFoundException: net$lingala$zip4j

. . . so not really further forward.

Edit : Sorry - I didn't follow your instructions correctly. My mistake.

EnriqueGonzalez · Jan 16, 2023

Brian Dean said:
net.lingala.zip4j

You are still missing the last part :
net.lingala.zip4j.ZipFile
what you had extra was the core part

you usually use the last line on this image:

Brian Dean said:
Array As String(zipFile)

dont use array as string, this is actually creating a constructor and passing parameters it is not passing the parameters directly so even if the method requires an String, you want to use a simple Array

if it still fails, share the .jar file you are using, you may be even using a different version

Brian Dean · Jan 16, 2023

... what you had extra was the core part

Thank you @EnriqueGonzalez - that worked. I also had to remove the second line (constants InitializeStatic ....).

B4J Question How to use an Additional JAR

Brian Dean

Well-Known Member

EnriqueGonzalez

Daestrum

Expert

Brian Dean

Well-Known Member

EnriqueGonzalez

Expert

Brian Dean

Well-Known Member

Similar Threads

B4J Question How to use an Additional JAR

Brian Dean

Well-Known Member

Daestrum

Expert

Brian Dean

Well-Known Member

EnriqueGonzalez

Expert

Brian Dean

Well-Known Member

Similar Threads

Privacy & Transparency

Privacy & Transparency