小编zzz*_*991的帖子

我试图创建/运行一个基本的JSP并遇到以下错误.我看到其他人遇到了类似的问题,但是,我还没能找到(或正确实施)手头问题的解决方案.任何帮助,将不胜感激!

    SEVERE: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/SimpleServletProject]]
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:816)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/SimpleServletProject]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
    ... 6 more
Caused by: java.lang.NoClassDefFoundError: HttpServletRequest
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2693)
    at java.lang.Class.getDeclaredMethods(Class.java:1967)
    at org.apache.catalina.util.Introspection.getDeclaredMethods(Introspection.java:127)
    at org.apache.catalina.startup.WebAnnotationSet.loadMethodsAnnotation(WebAnnotationSet.java:287)
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:140)
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:65)
    at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:415)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:892)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:386)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
    at …

我正在使用 Vim，但无法使用默认绑定键切换到我的窗口之一<ctrl+w> j。我打开了三个窗口，右下角的窗口无法访问。为什么会发生这种情况？

我正在研究"Accelerated C++".我对问题5-3有疑问.它问:

5-3. By using a typedef, we can write one version of the program that implements either a
vector-based solution or a list-based one. Write and test this version of the program.'

接下来的问题是:

5-4. Look again at the driver functions you wrote in the previous exercise. Note that 
it is possible to write a driver that differs only in the declaration of the type for the data structure
that holds the input file. If your vector and list test …

Andrew Koenig的Accelerated C++问题 7-9 提问：

7-9。（困难）第 7.4.4/135 节中的 nrand 实现不适用于大于 RAND_MAX 的参数。通常，这个限制没有问题，因为无论如何 RAND_MAX 通常是最大可能的整数。尽管如此，在某些实现中 RAND_MAX 远小于最大可能的整数。例如，RAND_MAX 为 32767 (2^15 -1) 并且最大可能的整数为 2147483647 (2^31 -1) 的情况并不少见。重新实现 nrand，使其适用于所有 n 值。

如果n > RAN_MAX我的想法要采取

double temp = n/RAN_MAX + .5;
int mult = temp;
int randomNum = 0;

for (int i = 0; i != mult; mult++)
    randomNum += rand();

然后测试是否randomNum < n。这可以生成随机数> RAND_MAX吗？我不知道如何使用比我的计算机可以处理的更大的整数，所以我认为没有任何真正的方法可以分辨。

有人能够向我解释这段代码的含义吗？

private long GCD(long a, long b) {
            return b == 0 ? a : GCD(b, a % b);
        }

如果为零,则b等于a.否则GCD(b, a % b).这究竟是什么0意思？或者我误解了return b == 0 ? a : GCD(b, a % b);