小编Bab*_*ani的帖子

对于以下代码片段,我得到输出为1.我想知道它是怎么来的？

void main()
{
int x=10,y=20,z=5,i;
i=x<y<z;
printf("%d",i);
}

我执行下面的代码,发现输出是false.

import java.util.Set;
import java.util.HashSet;

public class Name {
    private String first, last;

    public Name(String first, String last) {
        this.first = first;
        this.last = last;
    }

    public boolean equals(Object o) {
        if (!(o instanceof Name))
            return false;
        Name n = (Name) o;
        return n.first.equals(first) && n.last.equals(last);
    }

    public static void main(String[] args) {
        Set<Name> s = new HashSet<Name>();
        s.add(new Name("Donald", "Duck"));
        System.out.println(s.contains(new Name("Donald", "Duck")));
    }
}

我想知道它的行为和输出的原因false.

为什么050不等于50以下代码段？

#include <stdio.h>
int main(void) {
    int x=050,y=50;
    int ans;
    ans= x==y ? x+3 : y+7;
    printf("%d\n",ans);
}

我们正在使用Java开发一个netbeans项目,它使用mysql数据库来处理一些常见的查询.但我遇到了在netbeans中加载mysql的jdbc驱动程序的问题.它给出了以下错误:

找不到类异常:com.jdbc.mysql.Driver请帮帮我.

在spring-hibernate项目中,我在eclipse中添加了一些User创建的库中所需的所有jar.但仍有一个例外,即ServletDispatcher不可用.下面显示了包含的所有jar文件,只是帮助我离开了哪一个.

org.springframework.aop-3.0.4.RELEASE.jar
org.springframework.asm-3.0.4.RELEASE.jar
org.springframework.aspects-3.0.4.RELEASE.jar
org.springframework.beans-3.0.4.RELEASE.jar
org.springframework.context.support-3.0.4.RELEASE.jar
org.springframework.context-3.0.4.RELEASE.jar
org.springframework.core-3.0.4.RELEASE.jar
org.springframework.expression-3.0.4.RELEASE.jar
org.springframework.instrument.tomcat-3.0.4.RELEASE.jar
org.springframework.instrument-3.0.4.RELEASE.jar
org.springframework.jdbc-3.0.4.RELEASE.jar
org.springframework.jms-3.0.4.RELEASE.jar
org.springframework.orm-3.0.4.RELEASE.jar
org.springframework.oxm-3.0.4.RELEASE.jar
org.springframework.test-3.0.4.RELEASE.jar
org.springframework.transaction-3.0.4.RELEASE.jar
org.springframework.web.portlet-3.0.4.RELEASE.jar
org.springframework.web.servlet-3.0.4.RELEASE.jar
org.springframework.web.struts-3.0.4.RELEASE.jar
org.springframework.web-3.0.4.RELEASE.jar
hibernate3.jar
jstl.jar
standard.jar
org.springframework.webflow-2.2.1.RELEASE.jar

StackTrace是:

SEVERE: Servlet /PersonLoanManegment threw load() exception
java.lang.ClassNotFoundException: org.springframework.web.servlet.DispatcherServlet
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1711)              
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1556)
at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:525)
at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:507)
at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:124)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1136)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1080)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5015)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5302)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1566)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1556)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)

我已经执行了一段代码.它如下所示:

#include<stdio.h>

main() {
int i=0;
fork();
printf("The value of i is:%d\n",++i);
fork();
printf("The value of j is:%d\n",++i);
fork();
wait();
}

我得到以下输出:

The value of i is:1
The value of j is:2
The value of i is:1
The value of j is:2
The value of j is:2
pckoders@ubuntu:~$ The value of j is:2

任何人都可以向我解释fork()和wait()函数在这里扮演什么角色？

我试图用很少的常量创建枚举.我希望枚举成为单身人士.使用下面的代码,我在eclipse中遇到编译错误:

语法错误,插入")"

在第5行完成方法声明.我无法找出错误.

public enum Days {

      SUNDAY,MONDAY,TUESDAY,WEDNESDAY,THURSDAY,FRIDAY,SATURDAY;

      INSTANCE; // line 5

      public Days getInstance() {
        return INSTANCE;
     }
}

我有以下代码片段,我得到的输出是4.请解释我是否需要i = 2或0.我很困惑.输出是4怎么样？

int main() {  
   int i=2;
   for(i=0;i<2;i++) {
      i=i%3;
      if(i==2) {
          i++;
          continue; }
      else
          ++i;  
   }
   printf("%d",i); 
}