首页 \ 问答 \ 为什么我不能导入java.util.concurrent.ConcurrentSkipListMap(Why can't I import java.util.concurrent.ConcurrentSkipListMap)

为什么我不能导入java.util.concurrent.ConcurrentSkipListMap(Why can't I import java.util.concurrent.ConcurrentSkipListMap)

 这是我的代码：  
package DavidPackages.Other;

import java.util.concurrent.ConcurrentSkipListMap;

public class SkipListTest {
}
 
 这是我得到的错误：  
cannot find symbol class ConcurrentSkipListMap
 
 有任何想法吗？ 

Here is my code:  
package DavidPackages.Other;

import java.util.concurrent.ConcurrentSkipListMap;

public class SkipListTest {
}
 
Here is the error I get:  
cannot find symbol class ConcurrentSkipListMap
 
Any ideas? 

原文：https://stackoverflow.com/questions/10957882

更新时间：2023-08-15 12:08

最满意答案

 使用std::function  
class Test
{
    std::function<void()> func;
public:
    Test(const std::function<void()> &func) : func(func) {}

    void do_something()
    {
        func();
    }
};

void my_func()
{
    std::cout << "Hello" << std::endl;
}

int main()
{
    Test test(my_func);
    test.do_something();
}
 
 基于模板  
template <typename Func>
class Test
{
    Func *func;
public:
    Test(const Func &func) : func(func) {}

    void do_something()
    {
        func();
    }
};

void my_func()
{
    std::cout << "Hello" << std::endl;
}

int main()
{
    Test<void()> test(my_func);
//  Test<decltype(my_func)> test(my_func); // This is even better
    test.do_something();
}

Using std::function 
class Test
{
    std::function<void()> func;
public:
    Test(const std::function<void()> &func) : func(func) {}

    void do_something()
    {
        func();
    }
};

void my_func()
{
    std::cout << "Hello" << std::endl;
}

int main()
{
    Test test(my_func);
    test.do_something();
}
 
Template based 
template <typename Func>
class Test
{
    Func *func;
public:
    Test(const Func &func) : func(func) {}

    void do_something()
    {
        func();
    }
};

void my_func()
{
    std::cout << "Hello" << std::endl;
}

int main()
{
    Test<void()> test(my_func);
//  Test<decltype(my_func)> test(my_func); // This is even better
    test.do_something();
}

为什么我不能导入java.util.concurrent.ConcurrentSkipListMap(Why can't I import java.util.concurrent.ConcurrentSkipListMap)

最满意答案

使用`std::function`

基于模板

Using `std::function`

Template based

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