Still getting Nullpointer when envoking Native Android libs using Codename One NativeInterface

Question

I am building a Codename One applications that includes a 3rd party Android Lib. This means the use of NativeInterface. The 3rd Party lib is sreaderautolib_v1.1.jar. Used on Android to comms to a magstrip reader using the sound port.

I've included the jar in my CN1 project under the native\android folder.
I created a Swipe interface that extends the NativeInterface (package co.za.jaco.swiperapp.components;).
I right clicked on the Swipe interface and selected Generate Native Access and edited the resulting SwipeImpl under the native\android\co\za\jaco\swiperapp\components\ folder.
I also have the correct Android permissions specified in the CN1 build hints (android.xpermissions), this is to use the sound port.

I can build it (sending it to CN1 servers) and install it on my phone but keep on getting a Nullpointer after a certain line. I think my understanding on how to implement NativeInterfaces on CN1 is lacking and it is code related, but I cannot see the error.

Please help !!

Swipe :

package co.za.jaco.swiperapp.components;

import com.codename1.system.NativeInterface;

public interface Swipe extends NativeInterface {

public boolean Init();

public boolean isInit();

public void Start();

public void Stop();

public void SetMute(boolean mute);

public String GetErrorString();

public boolean Initial(long millis);

public String GetVersion(long millis);

public String GetKSN(long millis);

public String GetRandom(long millis);

public String ReadCard(long millis);

public String GetT1PAN(long millis);

public String GetT1HolderName_Exd(long millis);

public String GetT2PAN(long millis);

public String GetT2Exd(long millis);

public void Cancel();

public String GenerateWorkingKey(String random, String ksn);

public String TriDesDecryption(String dnc_key, String en_data);
}

SwipeImpl :

package co.za.jaco.swiperapp.components;

public class SwipeImpl {
private com.singular.hijack.autofreq.SReaderApi getSreaderInstance(){
    return com.singular.hijack.autofreq.SReaderApi.getSreaderInstance();
}
public void Start() {
    getSreaderInstance().Start();
}

public void Cancel() {
    getSreaderInstance().Cancel();
}

public void Stop() {
    getSreaderInstance().Stop();
}

public boolean Init() {
    return getSreaderInstance().Init();
}

public boolean isInit() {
    return getSreaderInstance().isInit();
}

public void SetMute(boolean param) {
    getSreaderInstance().SetMute(param);
}

public String GetErrorString() {
    return getSreaderInstance().GetErrorString();
}

public boolean Initial(long param) {
    return getSreaderInstance().Initial(param);
}

public String GetVersion(long param) {
    return getSreaderInstance().GetVersion(param);
}

public String GetKSN(long param) {
    return getSreaderInstance().GetKSN(param);
}

public String GetRandom(long param) {
    return getSreaderInstance().GetRandom(param);
}

public String ReadCard(long param) {
    return getSreaderInstance().ReadCard(param);
}

public String GetT1PAN(long param) {
    return getSreaderInstance().GetT1PAN(param);
}

public String GetT1HolderName_Exd(long param) {
    return getSreaderInstance().GetT1HolderName_Exd(param);
}

public String GetT2PAN(long param) {
    return getSreaderInstance().GetT2PAN(param);
}

public String GetT2Exd(long param) {
    return getSreaderInstance().GetT2Exd(param);
}

public String GenerateWorkingKey(String param, String param1) {
    return getSreaderInstance().GenerateWorkingKey(param,param1);
}

public String TriDesDecryption(String param, String param1) {
    return getSreaderInstance().TriDesDecryption(param,param1);
}

public boolean isSupported() {
    return true;
}
}

StateMachine :

Swipe swipe = (Swipe) NativeLookup.create(Swipe.class);
appendText("swipe.obj == null :" + (swipe == null));//says false
boolean bool = swipe.Initial(2500); **//THROW NULLPOINTER**
appendText("swipe.Initial(2500):" + bool);
boolean bool2 = swipe.isInit();
appendText("swipe.isInit():" + bool2);

Shai Almog Shai Almog · Accepted Answer · 2013-11-27T14:38:38

I'm guessing getSreaderInstance() returns null. I suggest connecting the device via DDMS and getting a full stack trace for the exception in the console.

Still getting Nullpointer when envoking Native Android libs using Codename One NativeInterface

1 Answers