Magic numbers in Java refer to hard-coded numeric values that are used without explanation or clarification within the code. These numbers seem to appear out of nowhere and can make the code difficult to understand and maintain. Using magic numbers in the code can lead to several problems. Firstly, it makes the code less readable and more difficult to comprehend. It becomes challenging for other developers to understand the purpose and significance of these numbers in the program. This can lead to confusion, errors, and inefficiencies in the codebase.
magic number
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External Websites- National Center for Biotechnology Information - PubMed Central - Magic numbers for metallic clusters and the principle of maximum hardness
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The Editors of Encyclopaedia Britannica Last Updated: Article History Table of Contents Category: Science & Tech Related Topics: shell atomic model (Show more)magic number, in physics, in the shell models of both atomic and nuclear structure, any of a series of numbers that connote stable structure.
The magic numbers for atoms are 2, 10, 18, 36, 54, and 86, corresponding to the total number of electrons in filled electron shells. (Electrons within a shell have very similar energies and are at similar distances from the nucleus.) In the chemical elements of atomic number 17 to 19, for example, the chloride ion (Cl − ), the argon atom (Ar), and the potassium ion (K + ) have 18 electrons in closed-shell configurations and are chemically quite stable. The number of electrons present in the neutral atoms constituting the relatively unreactive noble gases exactly correspond to the atomic magic numbers.
The magic numbers for nuclei are 2, 8, 20, 28, 50, 82, and 126. Thus, tin (atomic number 50), with 50 protons in its nucleus, has 10 stable isotopes, whereas indium (atomic number 49) and antimony (atomic number 51) have only 2 stable isotopes apiece. The doubly magic alpha particle, or helium-4 nucleus, composed of two protons and two neutrons, is very stable. In nuclei, this increased stability occurs when there is a large energy gap between a series of filled energy levels and the next level, which is empty. Such large gaps are said to separate shells, although these shells are not as clearly linked to the spatial structure of the nucleus as electron shells are to their orbits.
This article was most recently revised and updated by William L. Hosch.
Magic Number in Java
In programming, a magic number is a numeric value that is used directly in the code. It is used for identification purposes. In this section, we will discuss what is a magic number and how can we find a magic number through a Java program.
This can lead to confusion, errors, and inefficiencies in the codebase. Another problem with magic numbers is that they lack context and can often change over time. If these numbers need to be updated or modified, it can be challenging to identify all the instances they appear in the codebase.
Magic Number in Programming
A magic number is a hard-coded numeric value (text value in some cases) in the code that may change at a later stage. It seems like arbitrary and has no context or meaning. It is hard to update. For example:
Using such constant can help us distinguish the files among the many other file formats. For example:
- PDF Files begin with the magic text %PDF -> Hex (25 50 44 46)
- PNG Files begin with the magic text %PNG -> Hex (25 50 4E 47)
This can result in errors and bugs when these values are not updated consistently throughout the program. To avoid the use of magic numbers, it is recommended to use named constants or variables to represent these values. By giving these numbers a meaningful name, it becomes easier for developers to understand their purpose and significance in the code. Additionally, if these values need to be modified in the future, they can be updated in a single location, rather than searching for all occurrences throughout the program. In Java, the `final` keyword can be used to declare constants. By declaring a variable as `final`, its value cannot be changed once it is assigned. This allows developers to represent magic numbers as constants and give them meaningful names. Using constants instead of magic numbers enhances the readability, maintainability, and overall quality of the code. It promotes code reusability, reduces the chances of errors, and makes it easier for other developers to understand and work with the codebase..
Reviews for "Magic Numbers versus Constants in Java: Which is the Right Choice for Your Project?"
1. John Smith - 2 stars - I was really disappointed with "Magic numbers in java". The author didn't introduce any new concepts or insights, and the examples provided were just basic and uninteresting. The book felt more like a compilation of random code snippets rather than a comprehensive guide. It lacked depth and failed to engage me as a reader. Overall, I would not recommend this book to anyone looking to expand their knowledge in Java.
2. Sarah Johnson - 1 star - I found "Magic numbers in java" to be highly unhelpful and confusing. The explanations were convoluted, and it seemed as though the author just assumed that the reader already had advanced knowledge in Java. Additionally, the examples provided were overly complex and hard to follow, making it difficult for me to grasp the concepts being discussed. I regret purchasing this book and would not recommend it to others.
3. Michael Adams - 2 stars - "Magic numbers in java" was a letdown for me. The book promises to delve into the topic of magic numbers in Java, but it ultimately falls short. The author didn't provide any practical use cases or real-world examples, which left me feeling frustrated and unsatisfied. I was hoping for a comprehensive guide on how to avoid magic numbers and improve code readability, but this book did not deliver on that promise. I would recommend looking for other resources if you're interested in this topic.