block | 易学教程

How to make JTextField or JFormattedTextField accept input only if it matches a REGEX pattern?

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问题 I want a few JTextField within my program to only accept new input if it matches an specific Pattern . I know about JFormattedTextField 's masks and that is not what I want here. For each new input, the text should only accept the changes if those comply with the flow of an specific regex pattern. This has to be done with regex because of "regex-demanding" situations, like if the input should receive parts of itself. This is better understood with an example: Suppose my regex is "(\\d{2})-bk\

Hadoop HDFS

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Hadoop HDFS 概述：　　Hadoop有存储海量数据的分布式文件系统HDFS，有统一资源调度管理框架YARN，而且还有离线计算框架MapReduce。如果类比于各种操作系统，Hadoop可以认为是一个数据操作系统。Hadoop使用背景非常广泛。Hadoop实际使用几种实例；一、facebook使用 HiveQL进行数据分析，二、使用的Hive，实现淘宝搜索中的自定义筛选功能，三、使用的Pig运行Hadoop作业，实现Twitter和LinkedIn 上发现您可能认识的人功能，四、实现Amazon.com和淘宝上的商品协同过滤的推荐效果，五、Yahoo使用Hadoop，实现垃圾邮件的识别和过滤，还有用户特征建模功能。本文主要内容是解析Hadoop系统抽象的文件系统概念和分布式文件系统HDFS。一、HDFS（Hadoop Distributed File System） 1、NFS（Network File System）和HDFS（Hadoop Distributed File System）对比分析： 1、NFS是集中型文件系统，HDFS是分散型文件系统。 2、NFS文件系统的文件是存储在单一的NFS Server中，NFS Client通过网络连接可以从单一的NFS Server中获取文件同步到本地

How does Python print a variable that is out of scope

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问题 I have the following function in Python that seems to be working: def test(self): x = -1 # why don't I need to initialize y = 0 here? if (x < 0): y = 23 return y But for this to work why don't I need to initialize variable y? I thought Python had block scope so how is this possible? 回答1: This appears to be a simple misunderstanding about scope in Python. Conditional statements don't create a scope. The name y is in the local scope inside the function, because of this statement which is

JRuby: command pattern in Java with Ruby block: why does it work?

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问题 I am learning how to integrate Java library with Ruby code and come to the following question. I have a command pattern implemented in Java, as follows: public interface Command { public String execute(String param); } public class CommandRunner { public String run(Command cmd, String param) { return cmd.execute(param)+" [this is added by run method]"; } } When I import that to JRuby program I can implement Ruby class that respond_to? :execute with one parameter and pass it to the

How to block a website dynamically in C#?

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问题 I would like to block certain URLs dynamically from Windows Service written in C#. I don't want to do this by writing to hosts file. For example I would like to block the url http://example.com (in all browsers), but also block http://example.com/another from 7 to 8 am. Is this possible, what should I do? Best regards, Andrew 回答1: You might be able to use the Windows Firewall API. See the article, Managed classes to view/manipulate the Windows Firewall , by John Cole. 回答2: Now, I show the

Blocking package installation

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问题 Is it possible to block the installation of a package on a Honeycomb device? What I'd like to have is an application (or service or everything) that, once running, it inhibits subsequent installation of other packages. Let's suppose to be a service. While it runs, if the device user attempts an installation by the Market, it will be aborted. It is possible (continue supposing) to register an APPLICATION_IS_ABOUT_TO_BE_INSTALLED broadcast receiver that can break the PackageManager process?

Magento Layered Navigation block. Move to center

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In category.xml I'm changing the reference name in: <reference name="left"> <block type="catalog/layer_view" name="catalog.leftnav" before="-" template="catalog/layer/view.phtml"/> </reference> To content which I assumed would place the layered nav into the center. However, it still stays on the left. In fact, even I changed left to right , and it still doesn't move from the left sidebar. What am I doing wrong here? I managed to fix this (for anyone else who encounters this problem) by commenting out or deleting the below call in catelog.xml : <reference name="left"> <block type="catalog/layer

4.1、Bootstrap V4自学之路------组件---按钮

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1、一个示例  <button type="button" class="btn btn-primary">Primary</button>  <button type="button" class="btn btn-secondary">Secondary</button>  <button type="button" class="btn btn-success">Success</button>  <button type="button" class="btn btn-info">Info</button>  <button type="button" class="btn btn-warning">Warning</button>  <button type="button" class="btn btn-danger">Danger</button>  <button type="button" class="btn btn-link">Link</button> <button type=

Producer consumer implementation in a block device driver?

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问题 I'm trying to implement a producer-consumer like situation in my block level driver (on linux kernel version 2.6.39.1). My block driver's make_request_fn receives a stream of struct bio from a userlevel application. On receiving these BIOs, they are queued up. Next, I create a new struct bio which will hold all the information present in the queued BIOs. This new "merged_bio" will be submitted only if there is a struct request slot available in the lower level driver's request_queue . In the

Hadoop - how are map-reduce tasks know which part of a file to handle?

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问题 I've been starting to learn hadoop, and currently I'm trying to process log files that are not too well structured - in that the value I normally use for the M/R key is typiclly found at the top of the file (once). So basically my mapping function takes that value as key and then scans the rest of the file to aggregate the values needed to be reduced. So a [fake] log might look like this: ## log.1 SOME-KEY 2012-01-01 10:00:01 100 2012-01-02 08:48:56 250 2012-01-03 11:01:56 212 .... many more