Java Question Error parsing libraries - Object reference not set to an instance of an object.

[qle]

Hi,
I think trying to create a library from this SDK may have me beat.. i just dont have the skill level.

In my library java code i added a class within my class,

    private Barcode1D mInstance;[/INDENT]
public class c4000{
    private boolean isOpened = false;
    public int DeviceControlinit () throws IOException
    {
 
        try {
            //get 1D instance
            mInstance = Barcode1D.getInstance();
           //This actually now works thanks to DonManFred (well, i dont get an error)
            return 1;
        } catch (Exception e) {
            e.printStackTrace();

            return 0;
        }
    }


    public int openscanner () throws IOException
    {
            new InitTask().execute();
        return 1;
    }

    public class InitTask extends AsyncTask<String, Integer, Boolean> {

        @Override
        protected Boolean doInBackground(String... params) {
            // TODO Auto-generated method stub
            return mInstance.open();
        }

        @Override
        protected void onPostExecute(Boolean result) {
            super.onPostExecute(result);
            isOpened = result;

        }
    }

    etc.......
}

It is when i added the class,

public class InitTask extends AsyncTask<String, Integer, Boolean> {​

now causes a problem when i try to load the library in A4B, i get

Any help is very appreciated.

Lee.
in above my head...​

 

[Erel]

Is this class needs to be exposed to B4A? My guess that you can hide it with @Hide annotation.

 

[qle]

Adding the @Hide caused the SLC to throw an error on compile.

public int openscanner () throws IOException
    {
        new InitTask().execute();
        return 1;
    }

    @Hide
    public class InitTask extends AsyncTask<String, Integer, Boolean> {

        @Override
        protected Boolean doInBackground(String... params) {
            // TODO Auto-generated method stub
            return mInstance.open();
        }

        @Override
        protected void onPostExecute(Boolean result) {
            super.onPostExecute(result);
            isOpened = result;

        }
    }

SLC reports

Starting step: Compiling Java code.
javac 1.7.0_51
C:\Users\Lee\workspace\Serial_c4000\src\com\android\barcode1d\c4000.java:77: error: cannot find symbol
    @Hide
     ^
  symbol:   class Hide
  location: class c4000
1 error

So.. i removed the hide and changed the public class InitTask to private class InitTask
This then compiled ok, and B4A loaded the library without error.

I could even call the .openscanner that calls the private InitTask, and it returns a 1 to B4A ok..

But then, it throws an error

DeviceControlinit1
Open1
java.lang.RuntimeException: An error occured while executing doInBackground()
    at android.os.AsyncTask$3.done(AsyncTask.java:278)
    at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
    at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
    at java.lang.Thread.run(Thread.java:856)
Caused by: java.lang.ExceptionInInitializerError
    at com.rscja.deviceapi.Barcode1D.open(SourceFile:52)
    at com.android.barcode1d.c4000$InitTask.doInBackground(c4000.java:83)
    at com.android.barcode1d.c4000$InitTask.doInBackground(c4000.java:78)
    at android.os.AsyncTask$2.call(AsyncTask.java:264)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
    ... 5 more
Caused by: java.lang.UnsatisfiedLinkError: Couldn't load DeviceAPI: findLibrary returned null
    at java.lang.Runtime.loadLibrary(Runtime.java:365)
    at java.lang.System.loadLibrary(System.java:535)
    at com.rscja.deviceapi.DeviceAPI.<clinit>(SourceFile:526)
    ... 10 more

I seem to be back to this java.lang.UnsatisfiedLinkError: Couldn't load DeviceAPI:

yet the DeviceControlinit worked! (mInstance = Barcode1D.getInstance();) and this uses the DeviceAPI

​

Lee.

EDIT: Looking through the logs i see while loading the libDeviceAPI.so library that it sys "skipping init"

Trying to load lib /data/data/pos.c4000/files/libDeviceAPI.so 0x417ca960
Added shared lib /data/data/pos.c4000/files/libDeviceAPI.so 0x417ca960
No JNI_OnLoad found in /data/data/pos.c4000/files/libDeviceAPI.so 0x417ca960, skipping init
** Activity (main) Create, isFirst = true **

is this a clue?
does skipping init mean it failed to load?
and what is No JNI do i need it?

Lee.

 

[DonManfred]

cannot find symbol

you need to add the correct import to your imports

does skipping init mean it failed to load?

no. The library does not automatically init itself when loading. No problem if the lib has other methods to get initialized

and what is No JNI do i need it?

JNI is the "JAVA Native Interface".

 

[qle]

Thank you..

you need to add the correct import to your imports

May i ask, What is the correct import for @Hide?

 

[DonManfred]

import anywheresoftware.b4a.BA.Hide;

 

[qle]

Thank you

edit: This allowed it to complile as a public class,

    @Hide
    public class InitTask extends AsyncTask<String, Integer, Boolean> {

But back to same issue.
Caused by: java.lang.UnsatisfiedLinkError: Couldn't load DeviceAPI: findLibrary returned null


Lee.

 

[Erel]

How are you adding the .so file to the jar?

Where is the code that loads it?

 

[qle]

Im trying both Eclipse and SLC. (both give the same results)

In eclipse the .so file is in

/lib/armeabi/libDeviceAPI.so​

and the DeviceAPI.jar is in

/lib/DeviceAPI.jar​

(in eclipse i have added the /lib/DeviceAPI.jar as a referenced library)

With SLC the .so file is in

/lib/armeabi/libDeviceAPI.so
and
/additional/lib/libDeviceAPI.so​

and the DeviceAPI.jar is in

/lib/DeviceAPI.jar
and
/additional/lib/DeviceAPI.jar​

I load the libDeviceAPI.so from the java library with

static {
    //System.loadLibrary("serial_port");
    try {
       if (File.Exists(File.getDirInternal(), "libDeviceAPI.so") == true){
           //Log.i(TAG,"About to load: libDeviceAPI.so");
           System.load(File.Combine(File.getDirInternal(), "libDeviceAPI.so"));
           //Log.i(TAG,"Afterload: libDeviceAPI.so"); 
       }else{.........

edit: i also added the libDeviceAPI.so and DeviceAPI.jar into the files of the A4B project.
And the DeviceAPI.jar to the <program files>\Anywhere Software\Basic4android\Libraries

Lee.

 

[Erel]

Correct file structure:

You need to load it with:
System.loadLibrary("DeviceAPI"); //assuming that the file name is libDeviceAPI.so

 

[qle]

In the Java library i put

static {
        try {
               if (File.Exists(File.getDirInternal(), "libDeviceAPI.so") == true){
                     Log.i(TAG,"About to load: DeviceAPI");
                     System.loadLibrary("DeviceAPI");   //throws UnsatisfiedLinkError
                     //System.load(File.Combine(File.getDirInternal(), "libDeviceAPI.so")); // this loads ok, no errors loading (but get UnsatisfiedLinkError in InitTask: doInBackground)
........

​

throws error:

Caused by: java.lang.UnsatisfiedLinkError: Couldn't load DeviceAPI: findLibrary returned null​

In SLC the dir structure for libs is

and in armeabi

Lee.

 

[Erel]

1. The folder structure is incorrect. See the screenshot I posted. libs <> lib

2. Not sure what is the purpose of the if File.Exists check. It has nothing to do with the actual file.

 

[qle]

Oh my,
i missed that... i assumed because in the eclipse it was /libs that in the /additional would be also /libs (i copy and paste the folder!)... and i did not even notice... unbelievable!

This got me to the next step... thank you!


The file.exists is from at older project where i had to System.load the .so from the File.getDirInternal() to get it to work, if it was not there then it would copy it from File.getDirAssets(). (this actually worked!) i had assumed i may have to do the same with this .so...

Im not great at java... but im learning..

Thank you for your help.

edit: WhooHoo!.. it all works... SLC is indeed a very good utility for building libraries from 3rd party SDK's. (i still cant believe i missed the libs<>lib bit...)