使用 find 函数设置 STD C++

问题描述

假设我想在我的集合中找到指向元素 X 的指针。我会这样做：

set<int>S;
int x;
cin>>x;
//insert elements
set<int>iterator :: it = S.find(x);

我现在如何在我的集合中找到 x 之后的元素？例如，如果我的集合是 :1 、 2 、 3 并且 x 是 2 ，我想打印 3。这似乎不起作用：>

cout<<*(it+1);

它说不匹配运算符“+”。谢谢！

解决方法

而不是这个：

Task.WhenAll

这个：

private static final ConcurrentMap<String,ModuleDescription> cache = Maps.newConcurrentMap();

public void loadModules() {
    for (File file : Objects.requireNonNull(Main.getInstance().getDataFolder().listFiles())) {
        if (!file.getName().substring(file.getName().lastIndexOf(".")).equalsIgnoreCase(".jar")) {
            return;
        }
        registerModule(file);

        URLClassLoader loader = null;
        try {
            loader = new URLClassLoader(new URL[] { file.toURI().toURL() });
            Class<?> jarClass = loader.loadClass(cache.get(file.getName()).main);

            Method method = jarClass.getMethod("initialise");
            Object instance = jarClass.newInstance();
            method.invoke(instance);
        } catch (ClassNotFoundException | NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException | MalformedURLException e) {
            e.printStackTrace();
        } finally {
            if (loader != null) {
                try {
                    loader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

public void stopModules() {
    for (String module : cache.keySet()) {
        File file = new File(Main.getInstance().getDataFolder() + "/" + module);

        URLClassLoader loader = null;
        try {
            loader = new URLClassLoader(new URL[] { file.toURI().toURL() });
            Class<?> jarClass = loader.loadClass(cache.get(file.getName()).main);

            Method method = jarClass.getMethod("shutdown");
            Object instance = jarClass.newInstance();
            method.invoke(instance);
        } catch (MalformedURLException | ClassNotFoundException | NoSuchMethodException | IllegalAccessException | InvocationTargetException | InstantiationException e) {
            e.printStackTrace();
        } finally {
            if (loader != null) {
                try {
                    loader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

public void registerModule(File file) {
    JarFile jarFile = null;
    InputStream inputStream = null;
    try {
        jarFile = new JarFile(file);
        JarEntry jarEntry = jarFile.getJarEntry("module.yml");
        if (jarEntry == null) {
            System.out.println("The file \"" + file.getName() + "\" is missing the \"module.yml\"!");
            return;
        }

        inputStream = jarFile.getInputStream(jarEntry);
        Map<String,Map<String,String>> values = new Yaml().load(inputStream);

        ModuleDescription description = new ModuleDescription();
        if (values.containsKey("name")) {
            description.name = "" + values.get("name");
            System.out.println("name: " + description.name);
        }
        if (values.containsKey("main")) {
            description.main = "" + values.get("main");
            System.out.println("main: " + description.main);
        }

        if (description.name == null || description.main == null) {
            System.out.println("The \"module.yml\" is missing needed information's!");
            return;
        }


        if (values.containsKey("version")) {
            description.version = "" + values.get("version");
        }
        if (values.containsKey("author")) {
            description.author = "" + values.get("author");
        }
        if (values.containsKey("description")) {
            description.description = "" + values.get("description");
        }
        cache.put(file.getName(),description);
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (jarFile != null) {
            try {
                jarFile.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (inputStream != null) {
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}