Summary of "[s1 | 2025] Введение в программирование, Константин Бац, лекция 1"

Summary of the Lecture: “[s1 | 2025] Введение в программирование, Константин Бац, лекция 1”

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Main Ideas and Concepts

1. Course Introduction and Structure

• Lecturer: Konstantin Alexandrovich Bats.
• The course includes lectures, homework, and practical sessions (internships).
• Homework is done at home; during practice sessions, students receive quick modification tasks (~10-15 minutes) to implement.
• Homework has two difficulty levels: easy and hard; students start with easy.
• Homework submission deadlines allow delays of 0, 1, or 2 weeks, with penalties for late submission.
• Bonuses are awarded for first submissions and minor corrections (e.g., typo fixes).
• Tests occur at the end of the semester, with possible early tests during the session.

2. Motivation for Learning Java

• Java is a popular and widely used programming language, ranked high in 2025.
• It is safer than some languages (e.g., cannot accidentally damage system files).
• Java is used in server applications, Android mobile apps, desktop apps, and smart cards (SIM, bank cards).
• Java balances safety, performance, and applicability.
• Suitable for algorithmic and discrete math labs, where Python might be insufficient.
• C++ will be introduced in the second semester.

3. Java Fundamentals

• Java programs are written in human-readable text and compiled into bytecode.
• Bytecode runs on the Java Virtual Machine (JVM), which abstracts platform differences.
• This enables “write once, run anywhere” — the same bytecode runs on different OS and hardware platforms.
• JVM implementations (e.g., OpenJDK, Eclipse OpenJ9) exist for various platforms.
• Java editions:
  • Standard Edition (most common)
  • Enterprise Edition (paid, minor benefits)
  • Micro Edition (obsolete)
  • Java Card (for smart cards)

4. Java Versions and Support

• First stable Java released in 1996.
• Java 8 is widely used and introduced many improvements.
• New Java versions come every 6 months; LTS (Long Term Support) versions are released every 2 years.
• Current LTS versions: Java 17 and Java 21.
• Students are required to install Java 17 or newer.

5. Java Development Kit (JDK) vs Java Runtime Environment (JRE)

• JDK includes compiler, debugger, and development tools.
• JRE contains only the JVM and libraries to run Java programs.
• Developers need JDK; servers running Java programs only need JRE.

6. Performance and Just-In-Time (JIT) Compilation

• Java bytecode is interpreted by the JVM, which is slower than compiled machine code (e.g., C++).
• JVM uses JIT compilation to convert frequently executed code into machine code at runtime, improving speed.
• In some cases, Java programs can run faster than C++ due to runtime optimizations.
• Python uses a similar approach but is generally slower due to more complex memory management and lack of intermediate bytecode.

7. Memory Management and Garbage Collection

• Primitive types (e.g., int) are stored directly; objects like strings are stored by reference.
• Manual memory management (as in C/C++) can cause memory leaks.
• Java and Python use automatic garbage collection to free unused memory.
• Garbage collector tracks references to objects and frees memory when no references remain.
• Challenges include handling circular references, which Java solves using graph traversal.
• Garbage collection simplifies development and reduces memory errors.

8. Java Code Style and Best Practices

• Code formatting:
  • Use 4 spaces for indentation.
  • Opening curly braces on the same line.
  • Closing curly braces on a separate line.
• Naming conventions:
  • Classes: PascalCase (e.g., HelloWorld).
  • Methods and fields: camelCase starting with lowercase.
  • Constants: ALL_CAPS with underscores.
• Avoid very long lines (>120 characters).
• Use simple editors initially to learn manual compilation and running of code.

9. Neural Networks and Code Quality

• Neural networks can generate code but often produce low-quality, hard-to-maintain code.
• Students are encouraged to write clear, maintainable code themselves.
• Use of neural networks for homework is prohibited.

10. First Java Program: Hello World

• Create a class matching the filename.
• Define public static void main(String[] args) as the program entry point.
• Use System.out.println to print output.
• Compile with javac HelloWorld.java and run with java HelloWorld.
• Demonstrated handling command-line arguments and checking their length.
• Showed string indexing and character extraction (charAt method).
• Introduced conditional statements (if-else) and early return (return).
• Emphasized the need for variable initialization in Java.
• Demonstrated loops (for and while) for iterating over arguments.

11. String Methods and Documentation

• Java String class has many useful methods like toUpperCase(), indexOf().
• Students encouraged to read official Java documentation (javadoc) to learn about available methods.

12. Homework Assignments

• Homework 1: Install Java 21 or newer, compile and run sample Java programs.
• Homework 2: Write a program to sum integers passed as arguments (parsing strings with plus, minus, and whitespace).
• Emphasis on using int type for sums and printing results to standard output.
• Encouraged reading documentation for String and Number classes.
• Submission rules and deadlines explained.

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Detailed Methodologies / Instructions

Homework Submission Process

• Homework assigned during lectures.
• Submit completed homework at practice sessions.
• Receive a modification task to adjust your code in ~10-15 minutes.
• Submit both original and modified versions.
• Late submissions accepted with penalty points.
• Bonuses for first submissions and error corrections.

Java Program Compilation and Execution

• Write Java source code in .java file with class name matching filename.
• Compile using: bash javac ClassName.java
• Run using: bash java ClassName
• Pass command-line arguments as needed.
• Handle array length checks to avoid errors.

Basic Java Code Style

• Use 4 spaces for indentation.
• Opening brace on the same line as class/method declaration.
• Closing brace on a new line.
• Class names in PascalCase.
• Method and variable names in camelCase starting lowercase.
• Constants in ALL_CAPS with underscores.

Handling Command-Line Arguments

• Arguments passed as String[] args to main method.
• Access elements with zero-based indexing: args[0], args[1], etc.
• Check length with args.length.
• Use loops to iterate over arguments.

Memory Management Concept

• Understand difference between primitive types and objects.
• Recognize the role of references/pointers.
• Understand garbage collection basics: reference counting and graph traversal.
• Know that Java automates memory management.

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Speakers / Sources Featured

• Konstantin Alexandrovich Bats — main lecturer and presenter of the course.
• Andrey — briefly mentioned as a participant or assistant.
• References to external tools and documentation:
  • Java Language Specification (JLS)
  • Java Development Kit (JDK) documentation
  • Official Java API documentation (javadoc)
  • OpenJDK and Eclipse OpenJ9 JVM implementations

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This summary captures the key educational points, methodologies, and programming concepts introduced in the lecture, providing a coherent overview for students beginning their study of Java programming.

Category

Educational

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