小编Jos*_*lor的帖子

我正在寻找一种简洁的方法来将Iterator一个Stream或更具体的转换为"视图"迭代器作为流.

出于性能原因,我想在新列表中避免使用迭代器的副本:

Iterator<String> sourceIterator = Arrays.asList("A", "B", "C").iterator();
Collection<String> copyList = new ArrayList<String>();
sourceIterator.forEachRemaining(copyList::add);
Stream<String> targetStream = copyList.stream();

根据评论中的一些建议,我也尝试使用Stream.generate:

public static void main(String[] args) throws Exception {
    Iterator<String> sourceIterator = Arrays.asList("A", "B", "C").iterator();
    Stream<String> targetStream = Stream.generate(sourceIterator::next);
    targetStream.forEach(System.out::println);
}

但是,我得到了NoSuchElementException(因为没有调用hasNext)

Exception in thread "main" java.util.NoSuchElementException
    at java.util.AbstractList$Itr.next(AbstractList.java:364)
    at Main$$Lambda$1/1175962212.get(Unknown Source)
    at java.util.stream.StreamSpliterators$InfiniteSupplyingSpliterator$OfRef.tryAdvance(StreamSpliterators.java:1351)
    at java.util.Spliterator.forEachRemaining(Spliterator.java:326)
    at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:580)
    at Main.main(Main.java:20)

我已经看过StreamSupport和Collections,但我没有发现任何东西.

如何命名您创建的不同类/接口？有时我没有实现信息添加到实现名称 - 如接口FileHandler和类SqlFileHandler.

当发生这种情况时,我通常将该界面命名为"普通"名称,Truck并命名实际的类TruckClass.

在这方面,您如何命名接口和类？

在MDN文章面向对象的Javascript简介中关于继承的部分中,我注意到他们设置了prototype.constructor:

// correct the constructor pointer because it points to Person
Student.prototype.constructor = Student;  

这有什么重要意义吗？省略它可以吗？

是否存在在Java中命名枚举的约定？

我的偏好是枚举是一种类型.所以,例如,你有一个枚举

Fruit{Apple,Orange,Banana,Pear, ... }

NetworkConnectionType{LAN,Data_3g,Data_4g, ... }

我反对命名它:

FruitEnum
NetworkConnectionTypeEnum

我知道很容易找出哪些文件是枚举,但是你也可以:

NetworkConnectionClass
FruitClass

另外,是否有一个好的文档描述了常量,在哪里声明它们等等？

是否有任何markdown fork允许您引用其他文件,例如包含文件？具体来说,我想创建一个单独的markdown文件,其链接我经常调用但不总是(调用此B.md),然后当我在md文件中通过引用链接我正在写(A.md)时,我想喜欢它从其他文件(B.md)而不是从当前文件(A.md)的末尾拉取链接.

这是代码:

package mscontroller;

import javax.swing.*;
import com.apple.eawt.Application;

public class Main {
    public static void main(String[] args)
    {
        Application app = new Application();
        app.setEnabledAboutMenu(true);

        AMEListener listener = new AMEListener();
        app.addApplicationListener(listener);
        JFrame mainFrame = new JFrame("Application Menu Example");
        mainFrame.setSize(500, 500);
        mainFrame.setVisible(true);
    }
}

这是错误:

Exception in thread "main" java.lang.Error: Unresolved compilation
problems:   Access restriction: The type 'Application' is not API
(restriction on required library
'/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/rt.jar')
    Access restriction: The constructor 'Application()' is not API
(restriction on required library
'/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/rt.jar')
    Access restriction: The type …

我的要求很简单:2列,右列有固定大小.不幸的是,我无法在stackoverflow和Google上找到有效的解决方案.如果我在自己的上下文中实现,那么每个解决方案都会失败 目前的解决方案是:

div.container {
    position: fixed;
    float: left;
    top: 100px;
    width: 100%;
    clear: both;
}

#content {
    margin-right: 265px;
}

#right {
    float: right;
    width: 225px;
    margin-left: -225px;
}

#right, #content {
    height: 1%; /* fixed for IE, although doesn't seem to work */
    padding: 20px;
}

<div class="container">
    <div id="content">
        fooburg content
    </div>
    <div id="right">
        test right
    </div>
</div>

我用上面的代码得到以下内容:

|----------------------- -------|
| fooburg content  |            |
|-------------------------------|
|                  | test right | 
|----------------------- -------|

请指教.非常感谢!

我正在尝试使用maven为一个名为"logmanager"的小型家庭项目生成一个可执行jar,就像这样:

如何使用Maven创建具有依赖关系的可执行JAR？

我将那里显示的代码段添加到pom.xml中,然后运行mvn assembly:assembly.它在logmanager/target中生成两个jar文件:logmanager-0.1.0.jar和logmanager-0.1.0-jar-with-dependencies.jar.当我双击第一个jar时出现错误:

Could not find the main class: com.gorkwobble.logmanager.LogManager. Program will exit.

当我双击jar-with-dependencies.jar时出现稍微不同的错误:

Failed to load Main-Class manifest attribute from: C:\EclipseProjects\logmanager\target\logmanager-0.1.0-jar-with-dependencies.jar

我复制并粘贴了路径和类名,并检查了POM中的拼写.我的主要类从eclipse启动配置启动.有人可以帮我弄清楚为什么我的jar文件不会运行？另外,为什么有两个罐开始？如果您需要更多信息,请与我们联系.

这是完整的pom.xml,供参考:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.gorkwobble</groupId>
  <artifactId>logmanager</artifactId>
  <name>LogManager</name>
  <version>0.1.0</version>
  <description>Systematically renames specified log files on a scheduled basis. Designed to help manage MUSHClient logging and prevent long, continuous log files.</description>
  <build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>2.2</version>
            <!-- nothing here -->
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.2-beta-4</version>
            <configuration>
              <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
              </descriptorRefs>
              <archive>
                <manifest>
                  <mainClass>com.gorkwobble.logmanager.LogManager</mainClass> …

我有非常简单的persistance.xml文件:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
    xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">

    <persistence-unit name="eventractor" transaction-type="RESOURCE_LOCAL">
        <class>pl.michalmech.eventractor.domain.User</class>
        <class>pl.michalmech.eventractor.domain.Address</class>
        <class>pl.michalmech.eventractor.domain.City</class>
        <class>pl.michalmech.eventractor.domain.Country</class>

        <properties>
            <property name="hibernate.hbm2ddl.auto" value="validate" />
            <property name="hibernate.show_sql" value="true" />
        </properties>
    </persistence-unit>

</persistence>

它的工作原理.

但是当我删除<class>元素时,应用程序看不到实体(所有类都带有注释@Entity).

是否有任何自动机制来扫描@Entity类？

在maven多模块项目中,我希望每个模块始终保持与父模块相同的版本,我通常在模块的pom.xml中执行以下操作:

  <parent>
    <groupId>com.groupId</groupId>
    <artifactId>parentArtifactId</artifactId>
    <version>1.1-SNAPSHOT</version>
  </parent>

  <groupId>com.groupId</groupId>
  <artifactId>artifactId</artifactId>
  <packaging>jar</packaging>
  <version>${project.parent.version}</version>
  <name>name</name>

自从我开始使用maven 3.0-alpha-5以来,我收到了以下警告.

[WARNING] 
[WARNING] Some problems were encountered while building the effective model for com.groupid.artifactId:name:jar:1.1-SNAPSHOT
[WARNING] 'version' contains an expression but should be a constant. @ com.groupid.artifactId:name::${project.parent.version}, /Users/whaley/path/to/project/child/pom.xml
[WARNING] 
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING] 
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]

我很想知道将模块的版本绑定到父版本的真正问题是,如果有的话？或者这是一个一般警告的情况,当任何表达式,无论是否是project.parent.version,用于版本元素.