Question

我正在做一个程序，我需要将枚举值插入HashMap。我们真的能这样做吗？我在很多方面尝试过它，但失败了。

任何人都可以帮助我吗？通过该程序，我需要实现一个包含4个线程池（其名称作为键）的HashMap，对应于我有一个ThreapoolExcecutor对象。

以下是我的代码：

public class MyThreadpoolExcecutorPgm {
    enum ThreadpoolName
    {
        DR,
        PQ,
        EVENT,
        MISCELLENEOUS;
    }
    private static String threadName;
    private static HashMap<String, 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<String, ThreadPoolExecutor>();

        ThreadpoolName poolName ;
        tp = new ThreadPoolExecutor(poolsize, maxpoolsize, keepAliveTime,
                TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(5));

        threadpoolExecutorHash.put(poolName,tp);    //Here i am failing to implement currect put()


    }

Answer 1

您可以考虑在此处使用EnumMap代替HashMap。使用枚举值时，EnumMap比HashMap更快，更节省空间，这似乎正是您在这里所做的。

Answer 2

当然，可以将枚举作为地图中的键。

由于threadpoolExecutorHash从String映射到ThreadPoolExecutor，因此您收到错误，因为您尝试插入String（{{1} }}）作为关键。

从

改变

poolName

到

threadpoolExecutorHash = new HashMap<String, ThreadPoolExecutor>();

正如@templatetypedef所提到的，甚至还有一个特殊的Map实现，EnumMap专门用于将枚举用作键。

Answer 3

您使用String作为HashMap的键，您应该使用Enum类。您的代码应如下所示：

public class MyThreadpoolExcecutorPgm {
enum ThreadpoolName
{
    DR,
    PQ,
    EVENT,
    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>();

    ThreadpoolName poolName ;
    tp = new ThreadPoolExecutor(poolsize, maxpoolsize, keepAliveTime,
            TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(5));

    threadpoolExecutorHash.put(poolName,tp);    //Here i am failing to implement currect put()
}

将枚举值插入HashMap

3 个答案: