Deep Java

2026年1月19日

Java Type Casting Explained (Beginner to Advanced): Numeric Casting, Upcasting/Downcasting, instanceof, and Common Pitfalls

1. What Is Casting in Java? (Quick Answer) In Java, casting means treating a value or an object as a different type.You use casting when you want to convert numbers (like double to int) or when you wa […]

Java Fundamentals

2026年1月16日

Java API Explained: What It Is, How It Works, and How to Use It (Beginner Guide)

1. Introduction If you’re learning Java, you’ll quickly run into the term “Java API”.For example, classes like String, ArrayList, and LocalDate are used in many Java programs—and they are all part of […]

Object-Oriented Programming (OOP)

2026年1月16日

Java super Keyword Explained: Constructors, Methods, and Fields (With Examples)

1. Relationship Between Inheritance and super To understand Java’s super keyword, you should first understand inheritance.super is not something you memorize in isolation—its meaning becomes clear onc […]

Object-Oriented Programming (OOP)

2026年1月13日

Java Polymorphism Explained: How It Works, Examples, and Best Practices

1. What You Will Learn in This Article 1.1 Polymorphism in Java — Explained in One Sentence In Java, polymorphism means: “Treating different objects through the same type, while their actual behavior […]

Java Syntax Reference

2026年1月10日

Java Absolute Value Explained: Math.abs(), MIN_VALUE Pitfalls, and BigDecimal

1. What You Will Learn in This Article (Quick Summary) When working with Java, you may often need to calculate the absolute value of a number.The good news is that Java provides a simple and standard […]

Practical Java & API Usage

2026年1月10日

How to Compare Dates in Java (LocalDate, DateTime, Best Practices)

1. What You Will Learn in This Article (Conclusion First) When developers search for “java date comparison”, they usually want a clear and reliable way to compare dates without unexpected bugs.This ar […]

Java Fundamentals

2026年1月9日

Java Standard Input Explained: Scanner vs BufferedReader and Fast Input Techniques

1. What You Will Learn in This Article (Quick Conclusion) There are several ways to handle standard input in Java, but the key idea is simple: Choose the input method based on your purpose. You do not […]

Java Syntax Reference

2026年1月8日

Java Comparison Operators Explained: ==, !=, <, > and equals() Differences

1. What You Will Learn in This Article (Key Takeaways First) In Java, comparison operators are fundamental language features used to compare values such as numbers and characters.However, many beginne […]

Data Handling & Collections (Java Standard Library)

2026年1月8日

How to Sort a List in Java: list.sort, Comparator, Multiple Conditions, and Null Handling

1. What You Will Learn in This Article (The Shortest Way to Sort a Java List) When working with Java, it’s extremely common to run into situations where you need to sort a List.At the same time, many […]

Java Syntax Reference

2026年1月6日

Java OR Operator Explained: || vs |, Short-Circuiting, and Common Pitfalls

1. What Is “OR” in Java? In Java, OR is mainly used in conditional branching (such as if statements) to make a decision like “OK if either one is true.”It’s also a common stumbling point for beginners […]

Java String Concatenation Explained: Best Methods, Performance, and Best Practices

Java API Explained: What It Is, How It Works, and How to Use It (Beginner Guide)

Mastering Java’s compareTo(): Complete Guide With Sorting Examples

Java Standard Input Explained: Scanner vs BufferedReader and Fast Input Techniques

Java long Data Type Guide: MAX/MIN, Literals with L, Casting, and Overflow Safety

Java Type Casting Explained (Beginner to Advanced): Numeric Casting, Upcasting/Downcasting, instanceof, and Common Pitfalls

Java API Explained: What It Is, How It Works, and How to Use It (Beginner Guide)

Java super Keyword Explained: Constructors, Methods, and Fields (With Examples)

Java Polymorphism Explained: How It Works, Examples, and Best Practices

Java Absolute Value Explained: Math.abs(), MIN_VALUE Pitfalls, and BigDecimal

How to Compare Dates in Java (LocalDate, DateTime, Best Practices)

Java Standard Input Explained: Scanner vs BufferedReader and Fast Input Techniques

Java Comparison Operators Explained: ==, !=, <, > and equals() Differences

How to Sort a List in Java: list.sort, Comparator, Multiple Conditions, and Null Handling

Java OR Operator Explained: || vs |, Short-Circuiting, and Common Pitfalls