jvm-bytecode

问题 I try to new a inner staic class, But I find that bytecode appear the jvm instruction ACONST_NULL bwteen NEW , DUP and INVOKE_SPECIAL , But I know about a class new is NEW DUP INVOKE_SPECIAL package com.hoho.api; /** * @author linuxea */ public class Main { private static class InnerMain { // no field } public static void main(String[] args) { InnerMain innerMain = new InnerMain(); } } // class version 52.0 (52) // access flags 0x21 public class com/hoho/api/Main { // compiled from: Main.java

问题 I try to new a inner staic class, But I find that bytecode appear the jvm instruction ACONST_NULL bwteen NEW , DUP and INVOKE_SPECIAL , But I know about a class new is NEW DUP INVOKE_SPECIAL package com.hoho.api; /** * @author linuxea */ public class Main { private static class InnerMain { // no field } public static void main(String[] args) { InnerMain innerMain = new InnerMain(); } } // class version 52.0 (52) // access flags 0x21 public class com/hoho/api/Main { // compiled from: Main.java

问题 I am working on a REPL for a custom programming language of mine. It is implemented on top of the compiler, which it uses to generate the bytecode for the input and convert it to a Class<?> instance using the sun.misc.Unsafe.defineClass(String, byte[], int, int, ClassLoader, ProtectionDomain) method. The relevant code looks like this (irrelevant parts like exception handling omitted): void compileAndLoad(List<ICompilable> compilables) { List<Class<?>> classes = ...; for (ICompilable c :

来源： https://stackoverflow.com/questions/38784939/null-or-empty-lambda-as-default-value

来源： https://stackoverflow.com/questions/63077785/will-jvm-evaluate-a-obvious-return-value-on-each-execution

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 3 months ago . Improve this question JVM Run-time Data Areas separate stack for each method being executed. It contains operand stack and local variables. Every time you load a variable, you need to const to the operand stack and then store to the local variables. Why not directly operate

问题 Faced this java.lang.VerifyError with code snippet as below during JVM loading bytecode. try{ ----- } catch (NumberFormatException|CalculationException e) { } Here CalculationException is custom exception which extends java.lang.RuntimeException, while NumberFormatException is standard Java RuntimeException. While the code compile and run fine locally windows machine. It fails with VerifyError on one of the QA/prod/Dev unix node, and works fine on other unix node. While both unix nodes have

问题 I understand iload takes in integers -1 to 5, but how can you extend to higher numbers using a bipush instruction? How is the specific integer being stored with the bytecode? 回答1: There's several different instructions that can be used to push an integer constant. The smallest is the iconst_* instructions. These are only a single byte, because the value is encoded in the opcode itself. iconst_1, iconst_2, etc. are different opcodes. iconst_5 for example would be encoded as the byte 08 . Note:

问题 I understand iload takes in integers -1 to 5, but how can you extend to higher numbers using a bipush instruction? How is the specific integer being stored with the bytecode? 回答1: There's several different instructions that can be used to push an integer constant. The smallest is the iconst_* instructions. These are only a single byte, because the value is encoded in the opcode itself. iconst_1, iconst_2, etc. are different opcodes. iconst_5 for example would be encoded as the byte 08 . Note:

问题 In Java it is possible to create dynamic proxies using an implementation of InvocationHandler . Despite JVM optimizations, using reflection will always have some overhead invoking a method. To try to solve this problem, I tried to use ByteBuddy to create the proxy classes at runtime, but the documentation didn't seem clear enough on this aspect. How do I create a MethodCallProxy in order to forward a method invocation to some class instance? Edit: To better clarify my problem, I am providing