Java Programming – 100+ Practice Q&A on Syntax, Strings, Logic, File I/O – CS101

This document includes over 100 practice-based questions with accurate answers and Java syntax illustrations, designed for students enrolled in Intro to Java Programming (CS101) for the 2025/2026 academic year. It is an essential guide for first-year Computer Science, Software Engineering, and IT students, providing a firm grasp on Java programming foundations through a Q&A style tailored for learning and exam readiness. Each question is paired with a verified correct answer, many of which include full code examples, behavior clarifications, or common pitfalls. The document combines conceptual theory with applied programming logic, making it especially valuable for those preparing for assessments, coding labs, or entry-level Java certification exams. Covered topics include: Compilation & Execution: Java source files (.java), bytecode files (.class), use of javac and java commands Java IDEs & Tools: JDK, Java IDE, JVM, and compiler vs interpreter roles Syntax & Structure: method headers (main), reserved keywords, semicolon usage, valid class/method formats Input & Output: S, println, Scanner, JOptionPane, format specifiers using printf() Variables & Data Types: declaration, assignment, type matching, naming rules, constants, and numeric literals Control Structures: if-else, switch, loops (for, while), nesting, and condition evaluation Boolean Expressions & Logic: &&, ||, !, evaluation order, and truth conditions String Manipulation: substring(), charAt(), .equals(), string output control Operators & Arithmetic: precedence, assignment, increment/decrement, modular arithmetic Common Errors: compile-time vs logic errors, missing return statements, use of = vs == File I/O: reading and writing to text files using Scanner, File, and PrintWriter Math Class & Return Values: usage of M(), Mm(), and basic function design Algorithmic Thinking: pseudocode analysis, loop conditions, step-tracing, and logic simulations This material is ideal for: CS101 students preparing for upcoming Java quizzes, exams, or final reviews Java beginners looking for reinforcement through real example-based questions Self-taught learners reviewing Java syntax, I/O, and logic fundamentals Tutors assembling drills or entry-level practice tests Students targeting programming entrance tests with Java sections The format blends direct answers with practice-ready code insight, enabling both concept mastery and applied problem-solving in a structured and exam-friendly style. Keywords: Java practice questions, Java syntax, Java file I/O, Java Scanner, Java IDE, Java input output, Java logic, Java substring, Java Math class, Java data types, Java operators, Java loops, Java method return, CS101 Java, Java beginner exam prep