小编kas*_*ere的帖子

我需要下载一个json解析器,所以我去了jackson.codehaus.org网站.他们让我进入圈子,而不是点击和下载jar /罐子的方便链接.有谁知道罐子在哪里 - 确切地说？

这是我的班级:

public class A{
    private void doIt(int[] X, int[] Y){
       //change the values in X and Y
    }
}

我有另一个类试图doIt用来修改两个数组.我的代码中有错误但找不到它.

public class B{
  public void myStuff(){
    A myA = new A();
    int[] X = {1,2,3,4,5};
    int[] Y = {4,5,6,7,8,9};
    Method doIt = A.class.getDeclaredMethod("doIt",new Object[]{X,Y}); // error
    doIt.setAccessible(true);
    doIt.invoke(myA,new Object[]{X,Y});
  }
}

有关如何修复方法的任何帮助myStuff？

如果我使用getDeclaredMethod("doIt",new Object[]{X,Y});代码不编译.

如果相反,我getDeclaredMethod("doIt",null);就说了NoSuchMethodException.

我想从移动org.json到org.codehaus.jackson.如何转换以下Java代码？

private JSONObject myJsonMessage(String message){
    JSONObject obj = new JSONObject();
    obj.put("message",message);
    return obj;
}

try-catch为简单起见,我遗漏了这个街区.

我使用params 0.0.0.0在eclipse中运行appengine本地开发服务器

当我尝试访问任何方法时,我收到以下错误.如果我尝试访问api explorer,我会得到同样的错误

 http://localhost:8888/_ah/api/explorer

注意:我刚刚将我的应用引擎服务器更新为java 7.

有谁知道如何解决这个问题？

java.io.IOException: Failed to retrieve API configs with status: 500
    at com.google.api.server.spi.tools.devserver.ApiServlet.getApiConfigSources(ApiServlet.java:102)
    at com.google.api.server.spi.tools.devserver.ApiServlet.initConfigsIfNecessary(ApiServlet.java:67)
    at com.google.api.server.spi.tools.devserver.RestApiServlet.service(RestApiServlet.java:117)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:123)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:97)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:487)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at …

下面两个步骤:为什么产生在Java中不同的结果x = 31或32但同样的结果x=3？

int x=3;
int b = (int) Math.pow(2,x);
int c = 1<<x;

结果:

x=32: b=2147483647; c=1;
x=31: b=2147483647; c=-2147483648;
x=3:  b=8         ; c=8

我通常不会遇到JUnit注释的问题.但不知怎的,今天,在我新安装的Netbeans 7.2中,当我使用@Before注释时遇到以下错误:

annotation before is missing value for the attribute value

有谁知道如何解决这一问题？

UPDATE

我正在写一个mavenized web-app.对于TestCase,当我尝试导入org.junit.Before程序而不是导入时org.aspectj.lang.annotation.Before

我如何在jinja2中执行以下操作:

while apples < oranges:
    # some work here.

根据http://jinja.pocoo.org/docs/dev/extensions/#loop-controls,以及我得到的错误,Jinja2不支持while循环.

问题是我想继续做一些工作,只要价值apples小于oranges

谢谢你的帮助.

同样的东西while True:也是好的.

解决boggle的函数的最佳时间复杂度O(n)是多少,其中boggle board是n？

我觉得n^2因为每个角色都要看2(n-1)其他角色.采访者认为,这不是n^2一个O(1)字典查找.

given a unsorted set of n integers, return all subsets of size k (i.e. each set has k unique elements) that sum to 0.

So I gave the interviewer the following solution ( which I studied on GeekViewpoint). No extra space used, everything is done in place, etc. But of course the cost is a high time complexity of O(n^k) where k=tuple in the solution.

public void zeroSumTripplets(int[] A, int tuple, int sum) {
  int[] index = new int[tuple]; …

我有一个Login实体和一个Customer实体.Login.username是customer表中的外键.因此Java CustomerPOJO中的以下行

@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "username", nullable = false)
private Login login;

我的问题是:有没有一种简单的方法来查询customer表使用username？还是必须我第一次取login的username,然后customer用login？

这是JPA条件查询.而且,是的,我更愿意使用条件查询.

public Customer getCustomerByUsername(String username) throws EntityNotFoundException {
    CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
    CriteriaQuery<Customer> criteriaQuery = criteriaBuilder.createQuery(Customer.class);
    Root<Customer> root = criteriaQuery.from(Customer.class);
    Path<String> path = root.<String>get("username");
    criteriaQuery.where(criteriaBuilder.equal(path, username));
    return entityManager.createQuery(criteriaQuery).getSingleResult();
}

这条线Path<String> path = root.<String>get("username")正在抛出一个例外username ... is not present.