Android Question Calling Java Class

prajinpraveen · Feb 10, 2025

Hello Everyone,

I am trying to convert the following java code to B4A

1:

PrintTask printTask = new PrintTask();
printTask.setPrintBitmap(BitmapFactory.decodeResource(context.getResources(), R.drawable.printer));
Printer.getInstance().startPrint(printTask, new PrinterCallback() {

2:

// PrinterTask.Java

package com.pos.device.printer;

import android.graphics.Bitmap;

public class PrintTask {
  public int mStep;
 
  public Bitmap mBitmap;
 
  public PrintTask() {
    throw new RuntimeException();
  }
 
  public int getGray() {
    throw new RuntimeException();
  }
 
  public void setGray(int gray) {
    throw new RuntimeException();
  }
 
  public void addFeedPaper(int step) {
    throw new RuntimeException();
  }
 
  public void setPrintCanvas(PrintCanvas printCanvas) {
    throw new RuntimeException();
  }
 
  public void setPrintBitmap(Bitmap origBitmap) {
    throw new RuntimeException();
  }

  public void setPrintBuffer(byte[] buffer) {
    throw new RuntimeException();
  }
}

B4X:

    Dim bitmap As B4XBitmap = TextToBitmap("Text to Bitmap", 20, xui.Color_Black, "CENTER")
    Dim jo As JavaObject
    Try
        jo = jo.InitializeNewInstance("com.pos.device.printer.PrintTask",Null)
        jo.RunMethod("setPrintBitmap", Array As Object(bitmap))
    Catch
        Log(LastException)
    End Try


java.lang.RuntimeException
    at com.pos.device.printer.PrintTask.<init>(PrintTask.java:20)
    at java.lang.Class.newInstance(Native Method)
    at anywheresoftware.b4j.object.JavaObject.InitializeNewInstance(JavaObject.java:86)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:205)
    at anywheresoftware.b4a.debug.Debug.delegate(Debug.java:262)
    at com.test.sfpayments.main._print(main.java:496)
    at com.test.sfpayments.main._activity_create(main.java:488)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:351)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
    at com.test.sfpayments.main.afterFirstLayout(main.java:121)
    at com.test.sfpayments.main.access$000(main.java:33)
    at com.test.sfpayments.main$WaitForLayout.run(main.java:99)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6121)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1059)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:949)
(Exception) java.lang.Exception:  java.lang.RuntimeException

InitializeStatic initialises the class, but cannot run the SetPrintBitmap Method

3:

    Dim bitmap As B4XBitmap = TextToBitmap("Text to Bitmap", 20, xui.Color_Black, "CENTER")
    Dim jo As JavaObject
    Try
        jo = jo.InitializeStatic("com.pos.device.printer.PrintTask")
        jo.RunMethod("setPrintBitmap", Array As Object(bitmap))
    Catch
        Log(LastException)
    End Try
    
    Log(jo)
    
    Error occurred on line: 592 (Main)
java.lang.IllegalArgumentException: Expected receiver of type com.pos.device.printer.PrintTask, but got java.lang.Class<com.pos.device.printer.PrintTask>
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4j.object.JavaObject.RunMethod(JavaObject.java:132)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runVoidMethod(Shell.java:777)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:354)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:205)
    at anywheresoftware.b4a.debug.Debug.delegate(Debug.java:262)
    at com.test.sfpayments.main._print(main.java:496)
    at com.test.sfpayments.main._activity_create(main.java:488)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:351)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
    at com.test.sfpayments.main.afterFirstLayout(main.java:121)
    at com.test.sfpayments.main.access$000(main.java:33)
    at com.test.sfpayments.main$WaitForLayout.run(main.java:99)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6121)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1059)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:949)
(Exception) java.lang.Exception:  java.lang.IllegalArgumentException: Expected receiver of type com.pos.device.printer.PrintTask, but got java.lang.Class<com.pos.device.printer.PrintTask>
(Class) class com.pos.device.printer.PrintTask

Any assistance will be greatly appreciated.

Thank you

DonManfred · Feb 10, 2025

prajinpraveen said:
public PrintTask() { throw new RuntimeException(); } public int getGray() { throw new RuntimeException(); } public void setGray(int gray) { throw new RuntimeException(); } public void addFeedPaper(int step) { throw new RuntimeException(); } public void setPrintCanvas(PrintCanvas printCanvas) { throw new RuntimeException(); } public void setPrintBitmap(Bitmap origBitmap) { throw new RuntimeException(); } public void setPrintBuffer(byte[] buffer) { throw new RuntimeException(); }

This can not be the right code. All the code is doing is to create a RuntimeException.

prajinpraveen · Feb 10, 2025

this is what is see when i decompile the jar file. am i missing anything?

DonManfred · Feb 10, 2025

prajinpraveen said:
this is what is see when i decompile the jar file. am i missing anything?

- Do NOT decompile! The decompiler was not able to do its job.
- Use the original SOURCE files.

prajinpraveen · Feb 10, 2025

Thank you. will it help if i provide you with the SDK jar?

aeric · Feb 10, 2025

Is the code editor collapsed?
Can you click the minus button to reveal the code that may be hidden?

prajinpraveen · Feb 10, 2025

Hello Aeric. I trust you are doing well.

I have tried. it is expanded already and cannot expand it further

DonManfred · Feb 10, 2025

aeric said:
Can you click the minus button to reveal the code that may be hidden?

i guess the decompile just fails to decompile the jar and just create this methods.
A point more not to use a decompiler and instead use the sourcejars if there are available....

aeric · Feb 10, 2025

Why decompile the library?
Have you try interact with the jar using #AdditionalJars and JavaObject?

prajinpraveen · Feb 10, 2025

attached is a working project.

aeric · Feb 10, 2025

prajinpraveen said:
InitializeStatic initialises the class, but cannot run the SetPrintBitmap Method

I think InitializeNewInstance is correct.

prajinpraveen said:
java.lang.RuntimeException at com.pos.device.printer.PrintTask.<init>(PrintTask.java:20)

Need to figure out this error.

B4X:

    Try
        Dim jo As JavaObject
        jo.InitializeNewInstance("com.pos.device.printer.PrintTask", Null)
        jo.RunMethod("setPrintBitmap", Array As Object(bitmap))
    Catch
        Log(LastException)
    End Try

Daestrum · Feb 10, 2025

Maybe try

B4X:

    Dim pt As JavaObject
    pt.InitializeStatic("com.pos.device.printer.PrintTask")
    pt.RunMethod("setPrintBitmap",Array("load_your_image_here"))

prajinpraveen · Feb 10, 2025

Daestrum said:

Maybe try

B4X:

    Dim pt As JavaObject
    pt.InitializeStatic("com.pos.device.printer.PrintTask")
    pt.RunMethod("setPrintBitmap",Array("load_your_image_here"))

Thank you.

I have tried this. gives me the following error

Error occurred on line: 592 (Main)
java.lang.IllegalArgumentException: Expected receiver of type com.pos.device.printer.PrintTask, but got java.lang.Class<com.pos.device.printer.PrintTask>
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4j.object.JavaObject.RunMethod(JavaObject.java:132)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runVoidMethod(Shell.java:777)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:354)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:205)
at anywheresoftware.b4a.debug.Debug.delegate(Debug.java:262)
at com.test.sfpayments.main._print(main.java:496)
at com.test.sfpayments.main._activity_create(main.java:488)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:351)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
at com.test.sfpayments.main.afterFirstLayout(main.java:121)
at com.test.sfpayments.main.access$000(main.java:33)
at com.test.sfpayments.main$WaitForLayout.run(main.java:99)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6121)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1059)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:949)
(Exception) java.lang.Exception: java.lang.IllegalArgumentException: Expected receiver of type com.pos.device.printer.PrintTask, but got java.lang.Class<com.pos.device.printer.PrintTask>
(Class) class com.pos.device.printer.PrintTask

aeric · Feb 10, 2025

aeric said:

I think InitializeNewInstance is correct.

Need to figure out this error.

B4X:

    Try
        Dim jo As JavaObject
        jo.InitializeNewInstance("com.pos.device.printer.PrintTask", Null)
        jo.RunMethod("setPrintBitmap", Array As Object(bitmap))
    Catch
        Log(LastException)
    End Try

Usually I will try to Log the object to see it is successfully initialized.

B4X:

Try
    Dim jo As JavaObject
    jo.InitializeNewInstance("com.pos.device.printer.PrintTask", Null)
    Log(jo)
Catch
    Log(LastException)
End Try

prajinpraveen · Feb 10, 2025

aeric said:
Usually I will try to Log the object to see it is successfully initialized.

B4X:

Try Dim jo As JavaObject jo.InitializeNewInstance("com.pos.device.printer.PrintTask", Null) Log(jo) Catch Log(LastException) End Try

*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create (first time) **
printing
Error occurred on line: 582 (Main)
java.lang.RuntimeException
at com.pos.device.printer.PrintTask.<init>(PrintTask.java:20)
at java.lang.Class.newInstance(Native Method)
at anywheresoftware.b4j.object.JavaObject.InitializeNewInstance(JavaObject.java:86)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:205)
at anywheresoftware.b4a.debug.Debug.delegate(Debug.java:262)
at za.co.irays.sfpayments.main._print(main.java:506)
at za.co.irays.sfpayments.main._activity_create(main.java:498)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:351)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
at za.co.irays.sfpayments.main.afterFirstLayout(main.java:131)
at za.co.irays.sfpayments.main.access$000(main.java:43)
at za.co.irays.sfpayments.main$WaitForLayout.run(main.java:109)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6121)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1059)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:949)
** Activity (main) Resume **

Daestrum · Feb 10, 2025

What is it if you initialise as Static instead?

aeric · Feb 10, 2025

prajinpraveen said:
it is null

Do you put the sdk.jar into B4A Additional Libraries folder and add #AdditionalJars: sdk ?

DonManfred · Feb 10, 2025

prajinpraveen said:
IllegalArgumentException: Expected receiver of type com.pos.device.printer.PrintTask, but got java.lang.Class<com.pos.device.printer.PrintTask>

There is an Receiver expected here.

You need to have an receiver for PrintTask i guess.

prajinpraveen · Feb 10, 2025

aeric said:
Do you put the sdk.jar into B4A Additional Libraries folder and add #AdditionalJars: sdk ?

Yes I have

prajinpraveen · Feb 10, 2025

Daestrum said:
What is it if you initialise as Static instead?

I get the error as per post 13

https://www.b4x.com/android/forum/threads/calling-java-class.165540/post-1014973

Android Question Calling Java Class

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