j2js-jre | A modified subset of the Java Runtime API | Bytecode library

 by   decatur Java Version: Current License: Non-SPDX

kandi X-RAY | j2js-jre Summary

kandi X-RAY | j2js-jre Summary

j2js-jre is a Java library typically used in Programming Style, Bytecode applications. j2js-jre has no bugs, it has no vulnerabilities and it has low support. However j2js-jre build file is not available and it has a Non-SPDX License. You can download it from GitHub.

️ Deprecated. Consider adopting the TypeScript eco system. A modified subset of the Java Runtime API. This project is part of the Java Bytecode to JavaScript cross-compiler at

            kandi-support Support

              j2js-jre has a low active ecosystem.
              It has 6 star(s) with 2 fork(s). There are 1 watchers for this library.
              It had no major release in the last 6 months.
              j2js-jre has no issues reported. There are no pull requests.
              It has a neutral sentiment in the developer community.
              The latest version of j2js-jre is current.

            kandi-Quality Quality

              j2js-jre has 0 bugs and 0 code smells.

            kandi-Security Security

              j2js-jre has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
              j2js-jre code analysis shows 0 unresolved vulnerabilities.
              There are 0 security hotspots that need review.

            kandi-License License

              j2js-jre has a Non-SPDX License.
              Non-SPDX licenses can be open source with a non SPDX compliant license, or non open source licenses, and you need to review them closely before use.

            kandi-Reuse Reuse

              j2js-jre releases are not available. You will need to build from source code and install.
              j2js-jre has no build file. You will be need to create the build yourself to build the component from source.

            Top functions reviewed by kandi - BETA

            kandi has reviewed j2js-jre and discovered the below as its top functions. This is intended to give you an instant insight into j2js-jre implemented functionality, and help decide if they suit your requirements.
            • Compares this number with the specified double values
            • Compares two numbers
            • Reverse the buffer
            • Set the length of this string
            • Revers all characters in the builder
            • Appends characters to the buffer
            • Returns a fixed size list backed by the specified array
            • Inserts the specified element at the specified position in the list
            • Determines if the specified object is an instance - compatible object
            • Returns the superclass of this entity
            • Encodes a string using the given encoding scheme
            • Decodes a string
            • Invokes this Method
            • Converts this string to a character array
            • Init string from byte array
            • Returns a string representation of this map
            • Returns an array of all declared methods declared by this class or interface
            • Returns a hash code for this string
            • Sorts the given list in ascending order
            • Returns a string representation of this collection
            • Set the value of a field
            • Checks if two Objects are equal
            • Returns true if the specified object is equal to the specified list
            • Returns the formal parameter types of this method
            • Returns all annotations declared on this element
            Get all kandi verified functions for this library.

            j2js-jre Key Features

            No Key Features are available at this moment for j2js-jre.

            j2js-jre Examples and Code Snippets

            No Code Snippets are available at this moment for j2js-jre.

            Community Discussions


            Error while decompiling java class: ItemCollectionInvalidIndex: constants: requested 15873, limit 63
            Asked 2022-Feb-25 at 12:29

            I am decompiling java application, and i have already done with 99% .class files. But, I have a problem with couple of them: error while decompilation (errors are same type). Example:

            Procyon: java.lang.IllegalArgumentException: Argument 'index' must be in the range [0, 63], but value was: 15873...




            Answered 2022-Feb-25 at 12:29

            There is nothing wrong with all decompilers i have mentioned before.

            It was a constant_pool_count issue. It happened because of some JPHP decompiler offset troubles. So, if you are trying to reverse jphp applications, use your own software to delim .phb to .class blocks with couple of bytes before each of them

            Source https://stackoverflow.com/questions/70775342


            Does final keyword on method parameter get compiled to bytecode?
            Asked 2021-Dec-01 at 01:11

            I have the following class:



            Answered 2021-Nov-03 at 05:27

            The MethodParameters attribute is used to indicate that parameters are final. https://docs.oracle.com/javase/specs/jvms/se17/html/jvms-4.html#jvms-4.7.24

            In order for javac to add this attribute, you need to pass the -parameters option.

            Source https://stackoverflow.com/questions/69819621


            How does the JVM know how many values to pop into a new frame when invoking a method via invokevirtual?
            Asked 2021-Nov-22 at 13:26

            When a method is called via invokevirtual, the calling method pops off the values to pass to the called method along with the objectref and places them in the new stack frame.

            How does it know which stack entry is the objectref? My guess is that it does so by looking at the type of the called method and parses this to determine how many values to pop off, but this seems extremely inefficient. Is there some other mechanism that I'm overlooking?



            Answered 2021-Nov-20 at 06:36

            There's no one "right" way to do this, but the simplest strategy is to leave the values on the stack, and the called method refers to them via negative offsets. For example, if the called method has 3 params, they're referenced from the base stack offset minus 3, 2, and 1. Each is copied to a local variable and then referenced in the usual manner. The stack offset can be updated to reflect that the params have been consumed. Of course, each local param can also be initially assigned by a bunch of pops, one for each param.

            Other tricks can be performed to speed things up. There's no reason that local variables need to be stored differently than the stack. They can be stored on the stack itself. The passed in params occupy their original locations on the stack, and then additional space is allocated for the remaining local variables by just updating the stack offset. A base stack offset is remembered, and all local variables are referenced via the base offset.

            Essentially, a local variable is just like a stack slot, except it can be accessed at any time, regardless of what's currently been pushed on top.

            Source https://stackoverflow.com/questions/70043595


            Disassemble a Python script from the command line?
            Asked 2021-Nov-10 at 01:00

            With gcc you can use -S to stop compilation after your code has been compiled into assembly. Is there a similar feature with Python/bytecode? I know of ways like:



            Answered 2021-Nov-09 at 22:25

            If what you are looking for is the output of the disassembler, then you can run the module as a script:

            Source https://stackoverflow.com/questions/69905751


            Can someone explain CALL_FUNCTION and RETURN_VALUE from python bytecode
            Asked 2021-Nov-03 at 09:06

            I'm trying to understand python bytecode and I'm caught on CALL_FUNCTION and RETURN_VALUE.

            Does a function have its own stack? If not, what does the documentation mean by "Returns TOS to the caller of the function"?

            Sorry for the vagueness



            Answered 2021-Nov-03 at 09:06

            In CPython every function gets its own stack, it's called a frame in CPython and it's an implementation-specific detail(very old one) and other implementation of Python like IronPython1 and Jython doesn't have this functionality or implement it differently.

            To clarify when we say stack there are multiple stacks involved:

            1. Python stack: The stack of frame objects
            2. Function values stack: The values in each frame object are stored in this stack to be operated on within the scope of this frame2
            3. C stack: For C function calls

            When a function is called a new frame object is created first and placed on the Python stack. This frame object contains the code object of the function, global variables the function has access to, and also the local variables defined in the function get stored in the frame object.

            You can get the current frames in Python stack and current frame using the utilities provided in the inspect module.

            The issue with this is that it is a Python object, it has its own type PyFrame_Type, it gets reference count(gets all headers from PyVarObject) and consumes some memory and if we have a chain of function calls, each time we will be creating these frame objects in memory all over the heap.

            In Python 3.11, the frame object will be replaced by an array of structs that won't have an object header. The frame objects will still be available, but only if we request for it using inspect.currentframe() or sys._get_frame().

            2 Function values stack

            We can check stacksize of a function by accessing co_stacksize attribute of function's code object, this value is determined during the compilation time:

            Source https://stackoverflow.com/questions/69819950


            Why jump instead of return in Java bytecode?
            Asked 2021-Nov-02 at 16:39

            I compiled the following method:



            Answered 2021-Nov-02 at 16:39

            Frontend compilers generate code using simple patterns, and they rely on optimization passes to clean things up. At the point that the x == y expression is generated, the compiler doesn't "know" that the very next thing is a return statement. It could potentially check this, but that extra step can be handled just as easily with some sort of peephole optimizer.

            The benefit of a peephole optimizer is that it can perform cascading optimizations, that is, the result of one optimization can feed into the next one. The code that generated the x == y expression doesn't really have any way of performing anything more than one optimization step without adding more complexity.

            The java compiler used to have an optimization feature, but this was ditched in favor of HotSpot, which can perform even more powerful optimizations. Performing optimizations in the java compiler would slow it down and not really improve things all that much.

            Source https://stackoverflow.com/questions/69813756


            Do bytecode commands aligned?
            Asked 2021-Oct-07 at 15:06

            I know that compilers perform data structure alignment and padding according to 4-byte(for 32-bit systems) or 8-byte(64-bit systems) boundaries. But do interpreters align bytecode commands when they generate bytecode? If a command is coded by 1 byte and operands are coded by 1, 2, 4 or 8 bytes then it's seems it's not good for a processor to fetch data if bytecode is interpreted in looped switch? What do you think?

            P.S I'm not asking about interpreters that perform JIT.



            Answered 2021-Oct-07 at 15:06

            In general, the answer is no, but the JVM does require 32-bit alignment for the data portions of the lookupswitch and tableswitch instructions. Up to 3 bytes of padding (zeros) must be encoded to ensure proper alignment.

            Source https://stackoverflow.com/questions/69482663


            Java bytecode - Why is offset being skipped?
            Asked 2021-Oct-05 at 18:45

            I have this very simple class



            Answered 2021-Oct-05 at 18:44

            Yes, it's because they are double. In Java Virtual Machine Specification section 2.6.1 Local variables you can read:

            A single local variable can hold a value of type boolean, byte, char, short, int, float, reference, or returnAddress. A pair of local variables can hold a value of type long or double.

            Source https://stackoverflow.com/questions/69455383


            In the Java bytecode/class format, what determines if a method overrides another?
            Asked 2021-Sep-08 at 21:25

            I know that the bytecode specification allows classes to have methods with the same signature, differing only in the return type, unlike in the Java language. Some languages even make use of that under certain circumstances. My question is related to reflection:

            if in a class I find a (non-private) method with the same name and parameter types as (a non final, non private) one its superclass , and with a return type equal or being a subtype of the return type of the said method in the superclass, when can I assume that code invoking the 'supermethod' statically will always result in the execution of the 'overriding(?)' method (naturally assuming the call is made on an object which is of that class)? Even in cases of other languages compiled to the JVM bytecode, or if runtime code generation is involved, or in hacked synthetic classes like the lambda forwarders?

            My question was brought about from noticing how in the Scala standard library, an Iterable[E] has a method:



            Answered 2021-Sep-08 at 12:01

            It all eventually depends on the JVM instruction used:

            • invokespecial would invoke the method without doing dynamic resolution based on the type of current object.

            • invokevirtual would dispatch based on the class.

            Related: Why invokeSpecial is needed when invokeVirtual exists

            So the answer is it depends on the generated bytecode.

            Source https://stackoverflow.com/questions/69102562


            Java Bytecode Error : Expecting to find object/array on stack
            Asked 2021-Aug-24 at 12:44

            I am compiling a simple language into JVM Bytecode and having some issues with Java object method calls. The verifier gives the error below

            java.lang.VerifyError: (class: Test_1, method: main signature: ()V) Expecting to find object/array on stack

            and below is the generated Java source code from my bytecodes by IntelliJ



            Answered 2021-Aug-24 at 12:44

            The signature of ArrayList.get method at 22 is wrong.
            The correct one is (I)Ljava/lang/Object;

            Source https://stackoverflow.com/questions/68907543

            Community Discussions, Code Snippets contain sources that include Stack Exchange Network


            No vulnerabilities reported

            Install j2js-jre

            You can download it from GitHub.
            You can use j2js-jre like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the j2js-jre component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .


            For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .
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