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如何在JNI中从C ++调用Java方法(How to call Java methods from C++ in JNI)

 所以我正在编写一个使用大型c ++库的Android应用程序。 我有一切工作，以便java应用程序可以调用c ++委托方法，但我发现自己希望我可以将消息从c ++记录到Android日志。 这很容易从java中，但我不知道如何从c ++调用java方法。 我的搜索找到了从c ++中打开jvm的方法，这完全不是我想要做的。 理想情况下，我想将一个日志方法指针传递给c ++，然后可以随时使用它。 当然，java不支持方法指针。 我的java方法看起来像这样：  
private void log(String s){
   Log.i(Tag, s);     // Android log
}
 
 我只是不知道如何让c ++来访问这个方法。 

So I'm writing an Android app which uses a large c++ library. I have everything working so that the java app can call the c++ delegation methods, but I'm finding myself wishing I could log messages from c++ to the Android log. This is easy from java, but I'm at a loss as to how to call a java method from c++. My searches found methods for opening a jvm from c++, which is not at all what I want to do. Ideally, I'd like to pass a log method pointer to c++, which could then be used whenever I wanted. Of course, java doesn't support method pointers. My java method would look something like: 
private void log(String s){
   Log.i(Tag, s);     // Android log
}
 
I just don't know how to allow c++ to access this method.

原文：https://stackoverflow.com/questions/3902066

更新时间：2024-01-29 08:01

最满意答案

 迭代器（在你的情况下int i ）每次迭代增加1。 如果幻数无效，您可以将迭代器递减1。  
if (guess > randomNumber && guess <= 100){
    System.out.println("Your guess, "+guess+", is greater than the magic number.");
    // If the value of i at this point is 1
    i--; //Decrement i by 1
    // Now the value of i is 0. The value of i in the next iteration will be 1
}
else if (guess < randomNumber && guess > 0){
    System.out.println("Your guess, "+guess+", is less than the magic number.");
    // If the value of i at this point is 1
    i--; //Decrement i by 1
    // Now the value of i is 0. The value of i in the next iteration will be 1
}

The iterator (in your case int i) increment by 1 for each iteration. You can decrement your iterator by 1 if the magic number is invalid. 
if (guess > randomNumber && guess <= 100){
    System.out.println("Your guess, "+guess+", is greater than the magic number.");
    // If the value of i at this point is 1
    i--; //Decrement i by 1
    // Now the value of i is 0. The value of i in the next iteration will be 1
}
else if (guess < randomNumber && guess > 0){
    System.out.println("Your guess, "+guess+", is less than the magic number.");
    // If the value of i at this point is 1
    i--; //Decrement i by 1
    // Now the value of i is 0. The value of i in the next iteration will be 1
}

如何在JNI中从C ++调用Java方法(How to call Java methods from C++ in JNI)

最满意答案

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