Android - 如何启用CheckJni进行NDK开发？

dependencies {
    ...
    implementation 'com.android.support:support-annotations:28.0.0'
}

android {
    ...
    defaultConfig {
        ...
        externalNativeBuild {
            cmake {
                cppFlags ""
            }
        }
    }
    ...
}

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

extern "C" JNIEXPORT jstring JNICALL
Java_com_example_myapplication_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

public native String stringFromJNI();

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

    // Example of a call to a native method
    TextView tv = findViewById(R.id.sample_text);
    tv.setText(stringFromJNI());
}

static {
    System.loadLibrary("check_jni");
}

add_library(check_jni SHARED check_jni.cpp)