Is there a good available (standard Java) data structure to represent a tree in Java? Specifically I need to represent the following: The tree at any node can have an arbitrary number of children Each node (after the root) is just a String (whose children are also Strings) I need to be able to get all the children (some sort of list or array of Strings) given an input string representing
是否有一个好的可用（标准Java）数据结构来表示Java中的树？ 具体而言，我需要表示以下内容： 任何节点上的树都可以有任意数量的子节点 每个节点（在根之后）只是一个String（其子节点也是Strings） 我需要能够得到所有的孩子（某种列表或字符串数组），给定一个表示给定节点的输入字符串 有没有可用的结构或我需要创建自己的（如果这样的实施建议会很好）。 这里： public class Tree<T> { private Nod
Specifically looking for Java code tips and tricks of the trade for: reducing memory footprint increasing performance Personally would like to see answers focusing on the "how" and not the "when" as the consensus among savvy developers is that early optimization is a bad idea as you don't have anything to profile and thus don't know what the actual bottlenecks wi
具体查找Java代码提示和技巧的交易： 减少内存占用 提高性能 个人希望看到关于“如何”而不是“何时”的答案，因为精明的开发人员之间的共识是早期优化是一个坏主意，因为你没有任何东西要分析，因此不知道实际是什么瓶颈将会发生。 “我们应该忘记小效率，大约97％的时间：不成熟的优化是所有邪恶的根源” “在已建立的工程学科中，容易获得的12％的改进永远不会被认为是边际的，我相信软件工程中应该采用相同的观点” 唐纳
This is really two questions, but they are so similar, and to keep it simple, I figured I'd just roll them together: Firstly : Given an established Java project, what are some decent ways to speed it up beyond just plain in-code optimization? Secondly : When writing a program from scratch in Java, what are some good ways to greatly improve performance? Please stay away from general opti
这实际上是两个问题，但它们非常相似，为了简单起见，我想我会把它们放在一起： 首先 ：给定一个已建立的Java项目，有什么体面的方法可以加速超越简单的代码内优化？ 其次 ：在Java中从头开始编写程序时，有什么方法可以大大提高性能？ 除非特定于Java，否则请远离一般优化技术。 我之前曾问过关于Python和Perl的内容。 对于Java，我想知道有什么好的提示/技巧来提高性能，以及是否有任何特别好的Java分析器。 首先：
Spring web flow is a state machine of sorts for a user interacting with html pages. Traditionally, while a user is in a view state the system will wait until the user interacts with the page which will trigger some transition. Is it possible to force a transition or update a page without interaction from the user in spring web flow? For example, I may have a REST controller, or an AMQP listen
Spring Web Flow是一种用于与HTML页面交互的用户的状态机器。 传统上，当用户处于视图状态时，系统将等待用户与页面进行交互，这将触发一些转换。 在Spring Web Flow中，是否可以强制转换或更新页面而无需用户进行交互？ 例如，我可能有一个REST控制器或一个AMQP监听器，或者甚至可能只是一些后台进程正在运行。 当数据来自这些独立流程之一时，我想将用户更新为新的转换。 例如，用户坐在决策点一段时间，另一个服务将通
I would like to know, whether spring web flow supports springframework 3 release. According to the official documentation http://static.springsource.org/spring-webflow/docs/2.3.x/reference/html/ch10s02.html, spring 2.5 is used (config file), but as was mentioned stackoverflow:spring-3-spring-web-flow-2-dependencies-problem it should work with the springframework 3, so does it mean documentation
我想知道，春季web流程是否支持springframework 3发布。 根据官方文档http://static.springsource.org/spring-webflow/docs/2.3.x/reference/html/ch10s02.html，使用了spring 2.5（配置文件），但正如提到的那样：stackoverflow：spring- 3-spring-web-flow-2-dependencies-它应该与springframework 3一起工作，所以它意味着文档不是最新的，对于spring web flow样本也是如此，其中也使用spring 2.5。 所以，如果它支持，正确
I need to schedule a task to run in at fixed interval of time. How can I do this with support of long intervals (for example on each 8 hours)? I'm currently using java.util.Timer.scheduleAtFixedRate . Does java.util.Timer.scheduleAtFixedRate support long time intervals? 使用ScheduledExecutorService： private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
我需要安排一个任务以固定的时间间隔运行。 我如何在长时间间隔（例如每8小时）支持下做到这一点？ 我目前正在使用java.util.Timer.scheduleAtFixedRate 。 java.util.Timer.scheduleAtFixedRate是否支持长时间间隔？ 使用ScheduledExecutorService： private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1); scheduler.scheduleAtFixedRate(yourRunnable, 8, 8, TimeUnit.HOURS); 你应
I'm building a personal Web application using Java EE 6 Technologies (the container is an application server, Jboss AS 7). I'm starting from scratch to create repetitive background tasks, I identified two possible scenarios : Scheduled tasks (eg, sending bulk mails every sunday night) Trigger tasks based on web event (eg,running some long background updates from a web action) What
我正在使用Java EE 6技术构建个人Web应用程序（容器是应用程序服务器，Jboss AS 7）。 我从头开始创建重复的后台任务，我确定了两种可能的情况： 计划任务（例如，每周日晚上发送大量邮件） 基于Web事件触发任务（例如，从Web操作运行一些较长的后台更新） 我想避免的（我不知道是否可行）是让我的platformm散布一些背景任务（其中一些使用cron，其他使用TimerTask，db作业等）变得难以维护。 考虑到以前的两个要求，在
I am getting this error when I am running my eclipselink project. [EL Warning]: 2008.12.05 11:47:08.056--java.lang.NoClassDefFoundError: org/jboss/resource/adapter/jdbc/ValidConnectionChecker was thrown on attempt of PersistenceLoadProcessor to load class com.mysql.jdbc.integration.jboss.MysqlValidConnectionChecker. The class is ignored. Exception in thread "main" java.lang.NoClassDefFoundErro
我在运行我的eclipselink项目时遇到此错误。 [EL Warning]: 2008.12.05 11:47:08.056--java.lang.NoClassDefFoundError: org/jboss/resource/adapter/jdbc/ValidConnectionChecker was thrown on attempt of PersistenceLoadProcessor to load class com.mysql.jdbc.integration.jboss.MysqlValidConnectionChecker. The class is ignored. Exception in thread "main" java.lang.NoClassDefFoundError: org/jboss/resource/ad
I would like to lookup an enum from its string value (or possibly any other value). I've tried the following code but it doesn't allow static in initialisers. Is there a simple way? public enum Verbosity { BRIEF, NORMAL, FULL; private static Map<String, Verbosity> stringMap = new HashMap<String, Verbosity>(); private Verbosity() { stringMap.put(this.t
我想从它的字符串值（或可能的任何其他值）查找枚举。 我试过下面的代码，但它不允许在初始化程序中使用静态代码。 有一个简单的方法吗？ public enum Verbosity { BRIEF, NORMAL, FULL; private static Map<String, Verbosity> stringMap = new HashMap<String, Verbosity>(); private Verbosity() { stringMap.put(this.toString(), this); } public static Verbosity getVerbo
This is from Effective Java : // Implementing a fromString method on an enum type private static final Map<String, Operation> stringToEnum = new HashMap<String, Operation>(); static { // Initialize map from constant name to enum constant for (Operation op : values()) stringToEnum.put(op.toString(), op); } // Returns Operation for string, or null if string is
这来自Effective Java： // Implementing a fromString method on an enum type private static final Map<String, Operation> stringToEnum = new HashMap<String, Operation>(); static { // Initialize map from constant name to enum constant for (Operation op : values()) stringToEnum.put(op.toString(), op); } // Returns Operation for string, or null if string is invali