Displaying a native android alert dialog from C++ using JNI

activity.java

package com.yourpackage.appname;

import java.util.concurrent.Semaphore;

public class MyActivity extends NativeActivity {

    static {
        // Load native library
        System.loadLibrary("native-lib");
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    // Use a semaphore to create a modal dialog

    private final Semaphore semaphore = new Semaphore(0, true);

    // This function will be called from C++ by name and signature
    public void showAlert(final String message)
    {
        final MyActivity activity = this;

        ApplicationInfo applicationInfo = activity.getApplicationInfo();
        final String applicationName = applicationInfo.nonLocalizedLabel.toString();

        this.runOnUiThread(new Runnable() {
           public void run() {
               AlertDialog.Builder builder = new AlertDialog.Builder(activity, AlertDialog.THEME_HOLO_DARK);
               builder.setTitle(applicationName);
               builder.setMessage(message);
               builder.setPositiveButton("Close", new DialogInterface.OnClickListener() {
                   public void onClick(DialogInterface dialog, int id) {
                       semaphore.release();
                   }
               });
               builder.setCancelable(false);
               AlertDialog dialog = builder.create();
               dialog.show();
           }
        });
        try {
            semaphore.acquire();
        }
        catch (InterruptedException e) { }
    }
}

cpp_side.cpp

// androidApp is your native android application object declared like this:
// android_app* androidApp;

void showAlert(const char* message) {
	JNIEnv* jni;	
	androidApp->activity->vm->AttachCurrentThread(&jni, NULL);

	jclass clazz = jni->GetObjectClass(androidApp->activity->clazz);

	// Get the ID of the method we want to call
	// This must match the name and signature from the Java side
	// Signature has to match java implementation (second string hints a t a java string parameter)
	jmethodID methodID = jni->GetMethodID(clazz, "showAlert", "(Ljava/lang/String;)V");

	// Strings passed to the function need to be converted to a java string object
	jstring jmessage = jni->NewStringUTF(message);      
	
	jni->CallVoidMethod(androidApp->activity->clazz, methodID, jmessage);

	// Remember to clean up passed values
	jni->DeleteLocalRef(jmessage);

	androidApp->activity->vm->DetachCurrentThread();
}

This is not full c++ code since java code is still being used. I want Alertdialog fully in c++ with both setPositiveButton and setNegativeButton but I don't have knowledge in JNI in c++

Toast in c++ does didn't needed to be written in java like this https://github.com/Octowolve/Hooking-Template-With-Mod-Menu/blob/master/app/src/main/cpp/Includes/Utils.h#L74