bytecode

问题 There are some constructs that don't have equivalents in java. Examples would be named parameters instance private members Where/How does Scala store the information necessary for this stuff (some kind of flag in the first case, the parameter names in the second case? If I get it right this has to get stored in the byte code, since it works even if I just have a compiled library without the source code!? 回答1: This information is captured in an annotation named ScalaSig in the class file (see

问题 No The JIT compiler may "transform" the bytecode into something completely different anyway. It will lead you to do premature optimization. Yes You do not know which method will be compiled by the JIT, so it is better if you optimize them all. It will make you a better Java programmer. I am asking without really knowing (obviously) so feel free to redirect to JIT hyperlinks. 回答1: Yes, but to a certain extent -- it's good as an educational opportunity to see what is going on under the hood,

问题 As the title indicates, are there any C/C++ bytecode compilers/interpreters? I'm writing an application in an interpreted language that depends on certain libraries that are fully cross-compilable (there are no special flags to indicate code changes during compilation for a certain platform) but are written in C and C++. Rather than shipping n-platform-specific-libs with each platform, it would be nice to ship one set of libs which are interpreted by one platform specific interpreter.

问题 I try to implement several static analyses for Java bytecode. They try to compute if a certain method has a specific property, e.g. is a factory method. Because these analyses are difficult to test, I decided to write some Java code and annotate the methods directly with the correct property. After running the analysis, it is quite easy to check automatically whether the computed and the annotated property is the same. MyAnnotation: @Retention(RUNTIME) @Target(METHOD) public @interface

问题 I know that Java code is compiled into byte-code, that is executed by the JVM. What is the case with C# ? I have noticed that applications written in C# have the .exe extension what would suggest they are native machine instructions. but is it really so ? 回答1: No. Like Java, C# is compiled to an intermediary language (called MSIL or CIL). Unlike Java, the IL is stored in EXE files which have enough actual EXE code to show a dialog box asking users to install .Net. 回答2: C# compilation is done

问题 I've been thinking about checking jar file's hash value to determine if it has changed or not, but as it turns out the same jar file has different hashes every time I build it (export as jar file from eclipse, or build it using maven). I've removed manifest file's date values and stuff but it still is different. Is there something in bytecode generation which includes a timestamp or something? 回答1: A JAR file is a ZIP file and it contains a last modified date in its local file headers and

问题 I have a doubt in switch-case statement. Here is my code : String month = "April"; switch (month.toLowerCase()) { case "january": monthNumber = 1; break; case "february": monthNumber = 2; break; case "march": monthNumber = 3; break; case "april": monthNumber = 4; break; and so on.. I have 3 questions in this context: 1) While comparing month with the case values i.e case "January", case "February" .. What is exactly used from the following by compiler ?? - month.equals("case-value") ? - month

问题 I need to change a call to a function inside another function during run-time. Consider the following code: def now(): print "Hello World!" class Sim: def __init__(self, arg, msg): self.msg = msg self.func = arg self.patch(self.func) def now(self): print self.msg def run(self): self.func() def patch(self, func): # Any references to the global now() in func # are replaced with the self.now() method. def myfunc(): now() Then ... >>> a = Sim(myfunc, "Hello Locals #1") >>> b = Sim(myfunc, "Hello

问题 I'm trying to understand java byte code. I started with simple example: public class Test { public static void main(String args[]) { System.out.println(2 + 1); } } I compiled this class: javac Test.java And then I tried to a javap on the .class like this: javap -c Test which gave me this: Compiled from "Test.java" public class Test { public Test(); Code: 0: aload_0 1: invokespecial #1 // Method java/lang/Object."<init>":()V 4: return public static void main(java.lang.String[]); Code: 0:

问题 for bytecode instrumentation in java, there is the asm framework and the bcel and javaassist libraries. However I need to do instrumentation in native code, since some java classes are already loaded by the time the javaagent runs, eg java.lang.Thread, java.lang.Class, etc is there any library for instrumenting java classes in native code? Edit: Seems there is a bit of confusion. What I want is: Create a native java agent, which uses JVMTI apis to change the bytecode of a class while its