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JVM: The Constant Pool

Kamila Chyla published on 2022-02-02

It’s snowy, windy and dark outside. It is a perfect weather to read a technical spec, isn’t it?

Let’s read about a .classfile’s constant pool today.

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JVM: Names and Descriptors

Kamila Chyla published on 2022-01-26

This post is a note taken during reading 4.2 and 4.3 sections of chapter 4.

Section 4.2 describes the rules of representing class and interface names, field and method names, module and package names.

Section 4.3 describes descriptors and provides a short grammar according to which a representation of a type is constructed.

Names

Binary class and interface names

those names always appear in a fully qualified form known as binary name (see JLS 13.1)
they are represented with forward slash instead of a dot (for historical reasons)
represented as CONSTANT_Utf8_info structures
referenced from CONSTANT_NameAndType_info and from CONSTANT_Class_info structures

Field and method names

Unqualified names are used to strore:

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JVM: Class File Format - Structure

Kamila Chyla published on 2022-01-22

Class File

Each .class file contains the definition of a single:

class
interface or
a module

Class format (the specific order and meaning of bytes) described in the spec not neceserily applies to an actual file on the filesystem: those “bytes” might have been read from the database, downloaded from the web or constructed by a class loader; keep this in mind whenever you encounter the phrase “class file format”.

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JVM: Compiling for the JVM

Kamila Chyla published on 2022-01-16

Overview of JVM compilation - with samples and links to various interpreters on GitHub

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JVM: Instruction Set Summary

Kamila Chyla published on 2022-01-08

Here’s a short overview of the instruction set for the JVM.

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JVM: Structure of the JVM

Kamila Chyla published on 2022-01-07

Chapter 2 reading notes: types and runtime data areas, and a bit about threads. Opcodes will come soon 😄! Source: chapter 2 of JVM specification.

JVM: Introduction

Kamila Chyla published on 2022-01-04

Let’s start small: start by reading the specification’s introduction

How to learn the JVM

Kamila Chyla published on 2022-01-02

How to learn JVM? Is reading The JVM Specification a good idea? Here are some tips on how to approach JVM learning process.

How to create christmas tree - Canvas API

Kamila Chyla published on 2021-12-11

This post is a short tutorial which would guide you through some of the Canvas API in practice - I will draw a simple christmas tree using JavaScript and html canvas element.

Palettes - research notes

Kamila Chyla published on 2021-12-02

Generating a color palette

While playing with p5.js I often stumble upon a problem of color palette choice. The colors that I use in my artictic/programming playground are (usually) randomly generated. Even though I’m familiar with practical superiority of HSL/HSB over RGB colorscpace and I seldom use RGB in my scripts, I haven’t tried to create a color palette algorithm myself.

I’m sure there are many such algorithms. There are plenty of pages that allow the user to enter a color and they helpfully output a set of matching, somehow related colors that form some kind of a palette. The obvious target users of such pages are:

My coding journey

Disclaimer: it's just for fun