小编Dok*_*rNo的帖子

对于我的项目,我使用枚举,我需要实现switch-case语句,其中检查特定Enum的序数值,如下所示:

        switch ( variable )
        {
        case MyEnum.A.ordinal():
            return true;
        case MyEnum.B.ordinal():
            return true;
        default:
            return false;
        }

注意:返回值只是一个示例.

不幸的是,Eclipse(我使用1.6 JDK)给出了我的编译错误"case表达式必须是常量表达式".我该做什么？除了静态查找表之外是否还有其他方法,如下所述:从枚举序号转换为枚举类型？

考虑以下代码:

        SwingWorker<Void, Void> sworker = new SwingWorker<Void, Void>() {

        @Override
        protected Void doInBackground() throws Exception {
            ExecutorService executor = Executors.newFixedThreadPool(5);
            try {
                for (int j = 0; j < 5; j++) {
                    Callable<Object> worker = new MyCallableImpl();
                    Future<Object> future = executor.submit(worker); 
                    array[j] = future.get();
                }
            } catch (InterruptedException e) {
                // some code here
            } catch (ExecutionException e) {
                // some code here
            }
                // some code here
            executor.shutdown();
            return null;
        }

    };
    sworker.execute();

正如我在标题中所说:在SwingWorker的doInBackground()方法中调用ExecutorService是一个好习惯吗？它适用于我(JDK1.7),GUI没有被阻止,Executor池中的多个线程在后台运行,但我仍然有些疑惑......

我在Eclipse中编译OpenGL SFML C++项目时遇到错误(使用MinGW作为工具链):

对"gluNewQuadric @ 0"的未定义引用

对"gluQuadricDrawStyle @ 8"的未定义引用

未定义的引用`gluDeleteQuadric @ 4

违规代码在这里:

#include <SFML/Graphics.hpp>
#include <SFML/Window.hpp>
#include <SFML/System.hpp>   

sf::WindowSettings Settings;
Settings.AntialiasingLevel = 2;
Settings.DepthBits = 24;
Settings.StencilBits = 8;
sf::Window  App(sf::VideoMode(1024, 768, 32), "SFML Window", sf::Style::Close, Settings);
App.SetFramerateLimit(30);
prepareGL(App.GetWidth(), App.GetHeight());
sf::Clock Clock;
App.SetActive();
// GL goes here:
GLUquadricObj *qw1 = gluNewQuadric();
gluQuadricDrawStyle(qw1,GLU_POINT);
App.Display();
while (App.IsOpened()) {
    sf::Event Event;
    while (App.GetEvent(Event)) {
        if (((Event.Type == sf::Event::KeyPressed)
            && (Event.Key.Code == sf::Key::Escape))
            || (Event.Type == sf::Event::Closed)) {
            gluDeleteQuadric(qw1);
            App.Close();
        }
        if (Event.Type …