runtime | 易学教程

Annotation注解

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一注解的作用： 1. Annotation（注解）是JDK5.0引入的新技术。它不是程序本身，用于对程序作出解释（跟注释类似）。 2. 可以被其他代码读取（比如：编译器等） 3. 这里对于内部注解不做讨论，有兴趣可以自行百度二注解的格式：注解是以 “@注释名称(参数1，参数2...)” 在代码中存在。例如：@SupperssWarnings(value = "unchecked") 三注解的作用域：可以作用于：package , class , method , field等上面，相当于给他们添加了额外的辅助信息，我们可以通过反射机制等手段实现对这些元数据的访问。四自定义注解 package cn.foxsand.annotation; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * 1. @interface：声明一个注解类 * 2. value()：每一个方法实际上是声明了一个配置参数 * 2.1 方法名称 = 参数名称 * 2.2 返回值类型 = 参数的类型（返回值类型只能是

How to setup onFocusChangeListener() on a dynamically created set of editTexts?

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问题 i have this code in which i inflate a linearLayout containing 3 editTexts everytime an edittext of the previous lineaLayout loses focus. I want to have the onFocusChangeListener on the most recent created editTexts only. Instead, onFocusChangeListener is called only when the the first linearLayout loses focus and not the rest of others. protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.sale

Update WPF controls at run time

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问题 I'm trying to write a WPF application that will update a set of text boxes and labels at run time using threads but the problem is that when ever a thread tries to update the text boxes and labels I get the following error: "The calling thread cannot access this object because a different thread owns it." Is it possible to update the control at run time? 回答1: Yes, but you have to update the UI elements in the UI thread using Dispatcher.Invoke. Example in C#: Instead of myTextBox.Text = myText

Saving memory and compile time

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问题 Is there any way to save memory and compile time in perl using modules? For example not load all of the unneccessary, unused subs? Or it is a good way if I split my subs to many different pm files, and then I load only neccessary modules? For example: #!/usr/bin/perl -w sub mysub1() { use MySubsGroup1; } sub mysub2() { use MySubsGroup2; } This solution use less memory and get less compile time? Or what is the best practice to load only neccessary functions? 回答1: From perldoc autouse autouse -

Does the mono runtime already handle tail call optimisation as required by the IL spec?

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问题 I know that by this infamous post http://flyingfrogblog.blogspot.com/2009/01/mono-does-not-support-tail-calls.html the mono runtime did not offer tail call elimination as required by the IL. Has this changed since? 回答1: No, not yet. There's some work-in-progress on adding it, though : http://www.mail-archive.com/mono-devel-list@lists.ximian.com/msg24438.html (wish me luck ;-) ). 来源： https://stackoverflow.com/questions/3816148/does-the-mono-runtime-already-handle-tail-call-optimisation-as

Number of nested loops at runtime

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问题 I am trying to output all the possible unique integer combinations from 1 to max for a set number of integers. So for 3 integers and a max of 4 I would get: 123 124 134 234 I am doing this with nested for loops but I want to allow the user to input the number of integers at runtime. right now I have if(numInts >6); for(int x = 1; x < max; x++); if(numInts >5); for(int y = 1; y < max; y++); ... Is there a way to clean this up so I don't have to write out each possible integer for loop. PS: I

All pairs all paths on a graph

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问题 This is possibly a problem with possibly no optimal solution. Suppose I have a directed graph, have no clue whether it has any cycles or not(cycle detection will be one of the aspects of this problem). Given a set of vertices(possibly millions of vertices) I need to count all the distinct paths(paths with no duplicate vertices) between all the unique pairs of the given graph. How would I go about tackling this situation? Lets look at a brute-force way to do this: Compute all possible pairs

How many classes can PHP take?

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问题 Something I haven't seen a lot of on Google search or anything is questions about PHPs max class handling at runtime. Say I have a custom arrayaccess class that could house upto 8k objects of type "User". Since the arrayaccess class does not allow me to do: $d[0]->username = "sam" And set the class only for a residual object like I can in iterator when you do a foreach() each loop brings out an object but the array itself has got no objects in, it just assigns a new populated object (allowing

Installing PDT in Eclipse - No runtime option .. only SDK

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问题 Admittedly I am new to Eclipse. I have it configured properly for Android development but I want to add the PDT plug-in for PHP development. I have followed the instructions for updating PDT for the Galileo version of Eclipse located here ... http://wiki.eclipse.org/PDT/Installation When I search through the available PHP tools the only option is the PDT SDK feature. I was looking for the runtime option instead of the SDK. I don't want to install the SDK for PDT as I just want to use it and

Java 1.5.0.12 and custom Annotations at Runtime

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问题 I'm in a project where I need to use the above specific JAVA Version. And I wan't to use a custom annotation and query it's presence during RUNTIME using reflection. So I wrote an annotation, a class to annotate and a test class. The problem ist that, the annotation is not there. When I use one of the built in Annotations, everything is fine, the annotation is there. When I try my code under JAVA 1.6 everything is fine... Is there a known bug in this java version or do I need to add something