bytecode

I decompiled Java (actually Dalvik) bytecode. In the beginning of a method, I access a field of an instance member directly (i.e. not through a getter). It seems tha Java calls Object.getClass() on the accessed instance member ( mOther ), but doesn't use the result anywhere. Is this some sort of check? Why is this call needed? I suspect it is because I access a field directly (which is defined in that class), but I don't see the connection. The Java code and the decompiled bytecode are as follows. (Note that the last instruction loads lifeTime as constant 0x0001 because in MyOtherClass , I

I find that string concatenation seems to have less python bytecode than list join. This is an example. test.py: a = ''.join(['a', 'b', 'c']) b = 'a' + 'b' + 'c' Then I execute python -m dis test.py . I got the following python bytecode (python 2.7): 1 0 LOAD_CONST 0 ('') 3 LOAD_ATTR 0 (join) 6 LOAD_CONST 1 ('a') 9 LOAD_CONST 2 ('b') 12 LOAD_CONST 3 ('c') 15 BUILD_LIST 3 18 CALL_FUNCTION 1 21 STORE_NAME 1 (a) 3 24 LOAD_CONST 6 ('abc') 27 STORE_NAME 2 (b) 30 LOAD_CONST 4 (None) 33 RETURN_VALUE Obviously, the bytecode number of string concatenation is less.It just load string 'abc' directly. Can

This question already has an answer here: Where is array's length property defined? 7 answers How does array class work in Java? 4 answers If I use a normal class like List, Vector or something else, I get a size() function which returns the length of the regarded class but if I use an array of a class or a default data type I get a public member length which returns the current length of the array. int a[] = new int[3]; a.length; // used without () Vector<Integer> v = new Vector<Integer>(); v.length(); // used with () Why is that? I mean an array is not an own class isn't it? So if it is no

I want to intercept some method calls on one of my classes but those classes dont have a default constructor. Given the following class, how would I setup Byte Buddy to also create a public no-argument constructor to be able to create the generated class? public class GetLoggedInUsersSaga extends AbstractSpaceSingleEventSaga { private final UserSessionRepository userSessionRepository; @Inject public GetLoggedInUsersSaga(final UserSessionRepository userSessionRepository) { this.userSessionRepository = userSessionRepository; } @StartsSaga public void handle(final GetLoggedInUsersRequest request)

I'm working on an amateur JVM implementation, and I'm trying to make sure I have test coverage for all of the opcodes in the spec. I've gotten it down to the last few, but nop and swap have been eluding me. For example, here's a simple function that might use swap : static int do_swap() { int a = 56; int b = 32; return b%a; } But the bytecode produced by javac 1.6 avoids swapping in lieu of local storage: static int do_swap(); Code: 0: bipush 56 2: istore_0 3: bipush 32 5: istore_1 6: iload_1 7: iload_0 8: irem 9: ireturn Any ideas? None. The Java Language Specification does not provide such

we're writing some sort of compiler from Pascal to JVM Bytecode . And we've already implemented an expression tree generation, so the next step should be the creation of .class file. Can you suggest any guide/tutorial of how to generate any .class file at least from some static data? Because I've googled for 2 hours already and read JVM specification, but I really need some even simplest example to start developing the whole stuff. Someone has already written a widely-used byte code generation library: CGLIB . You'd have it knocked if you could figure out how to get your AST into CGLIB. Uko

AFAIK, in Java implicit constructors are always generated for a class without constructors [1] , [2] . But in bytecode I could not find such restriction on the JVMS . So: is it valid according to the JVMS to define a class without constructor only to use its static methods as in the following jasmin hello world? does it have any further consequences besides not being able to create instances of it? I won't be able to use invokespecial to initialize instances, which renders new useless according to https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.10.2.4 (can't use

Possible Duplicate: Way to have compiled python files in a separate folder? When python compiles modules to bytecode, it produces .pyc files from your .py files. My question is, is it possible to have these .pyc files written to a different directory than where the module resides? For example, I have a large directory of modules. Rather than having it littered with .pyc files, I would like to keep my source code in the directory and have a subdirectory like "bytecode" where all of the .pyc are stored. Is this possible? mikl This is answered in " Way to have compiled python files in a seperate