Android C ++ NDK

Question

我正在嘗試為android ndk編譯以下內容

#include <jni.h>
#include <string.h>

extern "C" {
    JNIEXPORT jstring JNICALL Java_com_knucklegames_helloCpp_testFunction(JNIEnv * env, jobject obj);
};

JNIEXPORT jstring JNICALL Java_com_knucklegames_helloCpp_testFunction(JNIEnv *env, jobject obj) {
 return env->NewStringUTF(env, "Hello from native code!");
}

但它給出了以下錯誤

Compile++ thumb: helloCpp <= /cygdrive/c/workspace/helloCpp/jni/main.cpp
/cygdrive/c/workspace/helloCpp/jni/main.cpp: In function '_jstring* Java_com_knucklegames_hello
Cpp_testFunction(JNIEnv*, _jobject*)':
/cygdrive/c/workspace/helloCpp/jni/main.cpp:10: error: no matching function for call to '_JNIEn
v::NewStringUTF(JNIEnv*&, const char [24])'
/cygdrive/d/android/android-ndk-r4b/build/platforms/android-8/arch-arm/usr/include/jni.h:839: note: candidates
 are: _jstring* _JNIEnv::NewStringUTF(const char*)
make: *** [/cygdrive/c/workspace/helloCpp/obj/local/armeabi/objs/helloCpp/main.o] Error 1

Answer 1

NewStringUTF函數只接受一個參數，一個c字符串：

env->NewStringUTF("Hello from native code!");

有一個C版本是這樣的：

NewStringUTF(env, "Hello from native code!");

但你顯然使用的是C ++版本。