Question

我之前也发过了类似的问题。我也澄清了我的怀疑。但我还需要更多东西。将使用枚举对象作为键并将线程池实例作为值来初始化Hashmap。我很困惑如何为其他一些进程调用的每个对象初始化HashMap。要弄清楚：我的程序MyThreadpoolExcecutorPgm.java初始化一个HashMap 我的Progran AdditionHandler.java通过传递ThreadpoolName（枚举）从HashMap请求一个线程。我收到“来自HashMap的无线程”消息。请帮帮我下面给出的是我的代码：

 public class MyThreadpoolExcecutorPgm {

    enum ThreadpoolName {
        DR, BR, SV, MISCELLENEOUS;
    }

    private static String threadName;
    private static HashMap<ThreadpoolName, ThreadPoolExecutor>
        threadpoolExecutorHash;

    public MyThreadpoolExcecutorPgm(String p_threadName) {
        threadName = p_threadName;
    }

    public static void fillthreadpoolExecutorHash() {
        int poolsize = 3;
        int maxpoolsize = 3;
        long keepAliveTime = 10;
        ThreadPoolExecutor tp = null;
        threadpoolExecutorHash = new HashMap<ThreadpoolName, ThreadPoolExecutor>();
        for (ThreadpoolName poolName : ThreadpoolName.) // failing to implement
        {
            tp = new ThreadPoolExecutor(poolsize, maxpoolsize, keepAliveTime,
                    TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(5));
            threadpoolExecutorHash.put(poolName, tp);
        }
    }

    public static ThreadPoolExecutor getThreadpoolExcecutor(
            ThreadpoolName poolName) {
        ThreadPoolExecutor thread = null;
        if (threadpoolExecutorHash != null && poolName != null) {
            thread = threadpoolExecutorHash.get(poolName);
        } else {
            System.out.println("No thread available from HashMap");
        }
        return thread;
    }
}

AdditionHandler.java

public class AdditionHandler{

    public void handle() {
        AddProcess setObj = new AddProcess(5, 20);
        ThreadPoolExecutor tpe = null;
        ThreadpoolName poolName =ThreadpoolName.DR; //i am using my enum    
        tpe = MyThreadpoolExcecutorPgm.getThreadpoolExcecutor(poolName);
        tpe.execute(setObj);
    }

    public static void main(String[] args) {
        AdditionHandler obj = new AdditionHandler();
        obj.handle();
    }
}

Answer 1

我怀疑你只是在寻找添加到每个枚举的静态values()方法：

for (ThreadpoolName poolName : ThreadpoolName.getValues())

或者，您可以使用EnumSet.allOf()：

for (ThreadpoolName poolName : EnumSet.allOf(ThreadpoolName.class))

（正如Bozho所说，EnumMap在这里是一个很好的选择。你仍然需要遍历枚举值。）

Answer 2

首先，您最好使用EnumMap。然后确保在调用方法之前填充了地图。

Answer 3

您可以按（按优先级降序排列）

之一迭代枚举值

for(Enum value : Enum.values())

for(Enum value : EnumSet.allOf(Enum.class))

for(Enum value : Enum.class.getEnumConstants())

但你也应该使用EnumMap。

用于枚举的HashMap作为键

3 个答案: