JNI GetFieldID调用时出现挂起的异常“java.lang.NoSuchFieldError”

Question

我不明白为什么我总是得到这个错误

public class MainActivity extends Activity {
    ...
    private FileDescriptor mFd;
}

JNIEXPORT jobject JNICALL Java_ua_taras_appc_MainActivity_configure (...)
{
 /* Create a corresponding file descriptor */
    {
        jclass cFileDescriptor = (*env)->FindClass(env, "java/io/FileDescriptor");
        jmethodID iFileDescriptor = (*env)->GetMethodID(env, cFileDescriptor, "<init>", "()V");
        jfieldID descriptorID = (*env)->GetFieldID(env, cFileDescriptor, "descriptor", "I");
        mFileDescriptor = (*env)->NewObject(env, cFileDescriptor, iFileDescriptor);
        (*env)->SetIntField(env, mFileDescriptor, descriptorID, (jint)fd);
    }
    return mFileDescriptor;
}

JNIEXPORT void JNICALL Java_ua_taras_appc_MainActivity_readuart (...)
{
    jclass MainActivityClass = (*env)->GetObjectClass(env, thiz);
    jclass FileDescriptorClass = (*env)->FindClass(env, "java/io/FileDescriptor");

    jfieldID mFdID = (*env)->GetFieldID(env, MainActivityClass, "mFd", "Ljava/io/FileDescriptor;");
    jfieldID descriptorID = (*env)->GetFieldID(env, FileDescriptorClass, "descriptor", "I");

    jobject mFd = (*env)->GetObjectField(env, thiz, mFdID);
    jint descriptor = (*env)->GetIntField(env, mFd, descriptorID);
}

Answer 1

因此没有这样的字段作为前面的结果

jfieldID mFdID = (*env)->GetFieldID(env, MainActivityClass, "mFd", "Ljava/io/FileDescriptor;");

这是您连续两次调用getFieldId()的唯一地方，但您未能检查错误。必须对所有JNI API调用进行错误检查。