I'm looking to use Java streams to solve this type of problem: I have a List of Library objects. The Library class contains a Map of Sections. The Sections contains a List of BookShelf objects. The BookShelf contains a Map of Book objects. class Library { Map<String, Section> sections = new HashMap<String, Section>(); String name; public String toString() {
我正在寻找使用Java流来解决这类问题： 我有一个库对象列表。 库类包含剖面图。 部分包含BookShelf对象的列表。 BookShelf包含一个Book对象的Map。 class Library { Map<String, Section> sections = new HashMap<String, Section>(); String name; public String toString() { return name; } } class Section { List<BookShelf> bookShelves = new ArrayList<BookShe
I have a simple issue. I have a program working in Java JDK7 but it doesn't work in JDK8 because of some introspection changes. Here is a test program to reproduce the issue: import java.beans.BeanInfo; import java.beans.IntrospectionException; import java.beans.Introspector; import java.beans.PropertyDescriptor; import java.util.ArrayList; import java.util.List; public class Main {
我有一个简单的问题。 我有一个使用Java JDK7的程序，但是由于一些内省的改变，它在JDK8中不起作用。 这是一个测试程序来重现这个问题： import java.beans.BeanInfo; import java.beans.IntrospectionException; import java.beans.Introspector; import java.beans.PropertyDescriptor; import java.util.ArrayList; import java.util.List; public class Main { public static void main(String[] args) throws Intr
First, here's a sample: public class Deadlock { static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s has bowed to me!%n", t
首先，这是一个示例： public class Deadlock { static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s has bowed to me!%n", this.nam
I understand that double locking in Java is broken, so what are the best ways to make Singletons Thread Safe in Java? The first thing that springs to my mind is: class Singleton{ private static Singleton instance; private Singleton(){} public static synchronized Singleton getInstance(){ if(instance == null) instance = new Singleton(); return instance; } } Does
我知道Java中的双重锁定被破坏了，那么在Java中使单线程安全的最好方法是什么？ 我想到的第一件事是： class Singleton{ private static Singleton instance; private Singleton(){} public static synchronized Singleton getInstance(){ if(instance == null) instance = new Singleton(); return instance; } } 这是否工作？ 如果是的话，这是否是最好的方法（我认为这取决于具体情况
Is it OK to use == on enums in Java, or do I need to use .equals() ? In my testing, == always works, but I'm not sure if I'm guaranteed of that. In particular, there is no .clone() method on an enum, so I don't know if it is possible to get an enum for which .equals() would return a different value than == . For example, is this OK: public int round(RoundingMode roundingMode) {
可以在Java中使用==来枚举，还是需要使用.equals() ？ 在我的测试中， ==总是有效，但我不确定是否可以保证。 特别是，在枚举中没有.clone()方法，所以我不知道是否有可能获得一个枚举，其中.equals()会返回与==不同的值。 例如，这是否正确： public int round(RoundingMode roundingMode) { if(roundingMode == RoundingMode.HALF_UP) { //do something } else if (roundingMode == RoundingMode.HALF_EVEN) {
I'm doing a file upload with Jersey, but I need only the filename. Internet Explorer sends the entire path, and based on what's in FormDataContentDisposition, Jersey parses out the slashes, so I can't even parse that. Thanks. Sounds like a difficult issue. The ideal case of course is to grab the string containing the slashes and just use string.split! Failing that, the only str
我正在使用Jersey进行文件上传，但我只需要文件名。 Internet Explorer发送整个路径，并且根据FormDataContentDisposition中的内容，Jersey分析出斜杠，所以我甚至不能解析它。 谢谢。 听起来像一个困难的问题。 理想的情况当然是抓住包含斜杠的字符串，并使用string.split！ 如果不这样做，我可以开始思考的唯一策略是尝试遍历字符串，看看文件夹是否存在字符串的第一部分的各种长度等。这可能会导致问题，但如果您打算
This question already has an answer here: What is 'Context' on Android? 30 answers In programming terms, it's the larger surrounding part which can have any influence on the behaviour of the current unit of work. Eg the running environment used, the environment variables, instance variables, local variables, state of other classes, state of the current environment, etcetera. I
这个问题在这里已经有了答案： Android上的“上下文”是什么？ 30个答案 在编程方面，它是较大的周边部分，可以对当前工作单元的行为产生任何影响。 例如使用的运行环境，环境变量，实例变量，局部变量，其他类的状态，当前环境的状态等等。 在某些API中，你可以在界面/类中看到该名称，例如Servlet的ServletContext ，JSF的FacesContext ，Spring的ApplicationContext ，Android的Context ，JNDI的InitialContext等。它们
I'm working on a project and I'm using a ImageView that is moved in onScroll, I recently implemented an onFling to detect swipe but I just saw that when I swipe the picture, the two MotionEvents from the onFling get the same X value using getX(). But that doesn't happen when doing swipe outside the view. Why can be this happening? Is there a way to fix it? Thanks! This is wha
我正在开发一个项目，我正在使用一个在onScroll中移动的ImageView，最近我实现了一个onFling来检测刷卡，但是我刚刚看到当我滑动图片时，onFling中的两个MotionEvents获得相同的X值使用getX（）。 但在视线外滑动时不会发生这种情况。 为什么会发生这种情况？ 有没有办法解决它？ 谢谢！ 这就是我想要实现的： @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
Note: This specific problem is solved, but there are serious follow-up problems. Have a look at GestureDetector - Detect double click in GridView item's although returning false in onTouchEvent() I want to detect double clicks on distinct items in a GridView of images. Therefore I assigned a separate OnTouchListener to each item- imageView in the getView() method of the adapter. The gest
注意：这个特定的问题已经解决，但是存在严重的后续问题。 看看GestureDetector - 检测GridView项目中的双击，虽然在onTouchEvent（）中返回false 我想要检测图像GridView中不同项目的双击。 因此，我分配一个单独OnTouchListener到每个商品imageView在getView()的适配器的方法。 gestureDetector是适配器类的成员变量。 private GestureDetectorCompat gestureDetector; public ImageGridViewAdapter(Context c, ArrayLi
I am a Java developer who has recently been thrust into wearing a Delphi developer hat. As is typically the case in such situations, I wind up trying to do things in Delphi while still using my 'Java' mindset, and I get confounded when they don't work. Today's issue is the notion of an interface. In Java, I can define an interface, give it some methods, and later declare a cl
我是一位Java开发人员，他最近被戴上了Delphi开发人员的帽子。 就像在这种情况下通常的情况一样，在我仍然使用我的'Java'思维模式的时候，我终于尝试在Delphi中做事情，当他们不工作时我感到困惑。 今天的问题是接口的概念。 在Java中，我可以定义一个接口，给它一些方法，然后声明一个实现该接口的类。 我试图在Delphi中做同样的事情，并且弄伤了我的手指。 我宣布了一个扩展IInterface的接口。 但是当实现这