JNI回调错误

Question

我在研究JNI的回电

null

JNIEXPORT jstring JNICALL
Java_com_example_arjunh_myapplication_MainActivity_getJniString(JNIEnv *env, jobject instance) {

jstring jstr = env->NewStringUTF("This string comes from JNI");

jclass clazz = env->FindClass("MainActivity");  // Error at this line

jmethodID messageMe = env->GetMethodID(clazz, "messageMe", "(Ljava/lang/String;)V");


jobject result = env->CallObjectMethod(instance, messageMe, jstr);

const char* str = env->GetStringUTFChars((jstring) result, NULL);
printf("%s\n", str);

env->ReleaseStringUTFChars(jstr, str);


return env->NewStringUTF("Hello from JNI!");
}

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    btnAdd = (Button) findViewById(R.id.btnAdd);
    tv = (TextView) findViewById(R.id.sample_text);

    btnAdd.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            getJniString();

        }
    });

}


public void messageMe(String text) {

    tv.setText(text);

}

 ClassNotFoundException: Didn't find class "MainActivity" on path: DexPathList[[zip file "/data/app/com.example.arjunh.myapplication-1/base.apk"],nativeLibraryDirectories=[/data/app/com.example.arjunh.myapplication-1/lib/arm64, /data/app/com.example.arjunh.myapplication-1/base.apk!/lib/arm64-v8a, /system/lib64, /vendor/lib64]]

Answer 1

我认为您应该按照文档中的建议指定包名称：

名称：完全限定的类名（即包名，用“/”分隔，后跟类名）。如果名称以“[”（数组签名字符）开头，则返回一个数组类。字符串以修改的UTF-8编码。

jclass clazz = env->FindClass("your/package/name/MainActivity")