CODEWITHSUNDEEP
androidreferencejava-native-interface
VinhJune
VinhJune

Reputation: 31

Android JNI stale local reference error

I am trying to call System.getProperty(String) from native code. but I got this error while trying to run on android 4.1.2:

    JNI ERROR: (app bug): accessed stale local reference ......... (index .... in a table of size 0)

The source code is as below:

JNIEXPORT jstring JNICALL Java_org_morphone_sense_device_DeviceSense_getArchNative
  (JNIEnv *pEnv, jobject pObj) {
jclass SCls = (*pEnv)->FindClass(pEnv, "java/lang/System");
if (!SCls)
    return NULL;
    jmethodID getPropertyMID = (*pEnv)->GetStaticMethodID(pEnv, SCls, "getProperty", "(Ljava/lang/String;)Ljava/lang/String;");
    jobject property = (*pEnv)->CallStaticObjectMethod(pEnv, SCls, getPropertyMID, "os.version");
}

Anyone knows how to fix this error?

Upvotes: 0

Views: 2388

Answers (2)

VinhJune
VinhJune

Reputation: 31

I found the problem. Instead of passing the string to CallStaticObjectMethod, I need to construct a jstring instance then pass it instead. The working code should be:

JNIEXPORT jstring JNICALL Java_org_morphone_sense_device_DeviceSense_getArchNative
  (JNIEnv *pEnv, jobject pObj) {
    jclass SystemCls = (*pEnv)->FindClass(pEnv, "java/lang/System");
    jstring propertyName = (*pEnv)->NewStringUTF(pEnv, "os.arch");

jmethodID getPropertyMID = (*pEnv)->GetStaticMethodID(pEnv, SystemCls, "getProperty", "(Ljava/lang/String;)Ljava/lang/String;");
jstring property = (*pEnv)->CallStaticObjectMethod(pEnv, SystemCls, getPropertyMID, propertyName);

if (property!=NULL) {
    __android_log_print(ANDROID_LOG_INFO, "Morphone", "Got property");
    return property;
}
else {
    __android_log_print(ANDROID_LOG_INFO, "Morphone", "Error: Cannot get property");
    return "";
}
}

Upvotes: 2

user207421
user207421

Reputation: 310860

Change

public native String getArchNative();

to

public String getArchNative()
{
    return System.getProperty("os.version");
}

and throw the JNI code away. Don't create work for yourself, or extra source files that need to be maintaned.

I would remove 'Native' from the method name too if it is possible at this stage.

Upvotes: 1

Related Questions