runtime

I did some reading up on JLS 15.7.4 and 15.12.4.2 , but it doesn't guarantee that there won't be any compiler/runtime optimization that would change the order in which method arguments are evaluated. Assume the following code: public static void main (String[] args) { MyObject obj = new MyObject(); methodRelyingOnEvalOrder(obj, obj.myMethod()); } public static Object methodRelyingOnEvalOrder(MyObject obj, Object input) { if (obj.myBoolean()) return null; else return input; } Is it guaranteed that the compiler or runtime will not do a false optimization such as the following? This optimization

golang爬珍爱网代码优化后，运行报了如下的错，找了半小时才找到原因，在此记录一下。 代码是这样的： 有一个interface类型的Parser： type Parser interface { Parser(contents []byte, url string) ParserResult Serialize() (funcName string, args interface{}) } 有一个struct类型的FuncParser： type FuncParser struct { parser ParserFunc funcName string } FuncParser 实现了Parser 接口： func (f *FuncParser) Parser(contents []byte, url string) ParserResult { return f.Parser(contents, url) } func (f *FuncParser) Serialize() (funcName string, args interface{}) { return f.funcName, nil } 抛开爬虫代码整体的复杂度，将代码简化到如下这样： type ParserFunc func(url string) string type FuncParser struct {

If I had the following code clock_t t; t = clock(); //algorithm t = clock() - t; t would equal the number of ticks to run the program. Is this the same is CPU time? Are there any other ways to measure CPU time in C++? OS -- Debian GNU/Linux I am open to anything that will work. I am wanting to compare the CPU time of two algorithms. clock() is specified to measure CPU time however not all implementations do this. In particular Microsoft's implementation in VS does not count additional time when multiple threads are running, or count less time when the program's threads are sleeping/waiting.

Java系列之注解 Java 注解（Annotation）又称之为 Java 标注、元数据，是 Java 1.5 之后加入的一种特殊语法，通过注解可以标注 Java 中的类、方法、属性、参数、包等，可以通过反射原理对这些元数据进行访问，注解的使用不会影响程序的正常运行，只会对编译器警告等辅助工具产生影响 注解功能 编译器可以使用注解来检测错误和取消警告； 使用注解可以生成特定代码，如 ButtferKnife 使用注解简化 findViewById等； 某些注解可以在运行时进行检查和操作。 注解定义 注解的定义使用 @interface 作为关键字，实际上表示自动继承了 java.lang.annotation.Annotation 接口，定义格式参考如下： @Target({ElementType.TYPE, ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) public @interface AuthValidators { @AliasFor("value") AuthValidator[] validators() default {}; } 内置注解 @Override 表示当前的方法将覆盖超类中的方法，编译时进行格式检查 @Target(ElementType.METHOD) @Retention

If I add a shutdown hook to my Java program's runtime like so: public class MyShutdownHook implements Runnable { @Override public void run() { // Stuff I want executed anytime // the program, Java, or the OS exits normally, // crashes, or terminates unexpectedly for any reason. } } // The in another method... Runtime.getRuntime().addShutdownHook(new MyShutdownHook()); ...then are there ever any situations where that run() method won't execute when the program/Java/OS exits normally, crashes or terminates unexpectedly? If so, what situations would be able to by-pass Runtime 's shutdown hook,

Is there any way that I can change enum values at run-time? e.g I have following type enum MyType { TypeOne, //=5 at runtime TypeTwo //=3 at runtime } I want at runtime set 5 to TypeOne and 3 to TypeTwo . Just refer to MSDN help HERE An enumeration type (also named an enumeration or an enum) provides an efficient way to define a set of named integral constants that may be assigned to a variable. Also HERE In the Robust Programming Section - Just as with any constant, all references to the individual values of an enum are converted to numeric literals at compile time . So you need to realign

I'm writing a program in scala which call: Runtime.getRuntime().exec( "svn ..." ) I want to check if "svn" is available from the commandline (ie. it is reachable in the PATH). How can I do this ? PS: My program is designed to be run on windows I'm no scala programmer, but what I would do in any language, is to execute something like ' svn help ' just to check the return code (0 or 1) of the exec method... if it fails the svn is not in the path :P Runtime rt = Runtime.getRuntime(); Process proc = rt.exec("svn help"); int exitVal = proc.exitValue(); By convention, the value 0 indicates normal