- Tokenize the input into numbers, operators, functions, parentheses.
- Use Shunting-yard to produce RPN.
- Evaluate RPN with a value stack.
This component is central to any advanced calculator and reusable across GUIs and console apps.
5 — Scientific Calculator Features
Goal: Build a scientific calculator on top of the parser with mathematics functions and constants.
Suggested features:
- Trigonometric functions (sin, cos, tan) and inverse
- Hyperbolic functions (sinh, cosh)
- Logarithms (log base 10, ln) and exponentials
- Factorials (n!), permutations and combinations
- Constants: pi, e
- Angle mode: degrees/radians/tgrads
- Unit conversions (optional)
Implementation tips:
- Use java.lang.Math for many functions; for extended functions, consider Apache Commons Math.
- For factorials beyond integer factorial, use Gamma function approximations from libraries.
- Carefully handle domain errors (e.g., sqrt of negative numbers) and floating-point precision.
6 — Programmer’s Calculator
Goal: Implement features useful for developers/work with binary, octal, decimal, hexadecimal, bitwise operators, and masks.
Key features:
- Convert between bases (2, 8, 10, 16)
- Bitwise AND, OR, XOR, NOT, shifts (<<, >>, >>>)
- Two’s complement representation, signed/unsigned modes
- Byte/word/dword/qword sizes
- Bit toggles and masks UI
Learning outcomes:
- Integer arithmetic, binary operations
- GUI elements for base selection and bit visualization
Example conversion:
int n = 255; String hex = Integer.toHexString(n); // "ff" String bin = Integer.toBinaryString(n); // "11111111" 7 — Graphing Calculator
Goal: Plot mathematical functions and optionally handle multiple curves, zoom/pan, and trace points.
Key features:
- Parse function strings like “sin(x) + x^2”
- Draw axes, gridlines, labels
- Zoom and pan controls
- Find roots, maxima/minima, intersections
- Export plots as images
Learning outcomes:
- Coordinate transforms and scaling
- Numerical sampling and adaptive subdivision for smoother curves
- GUI drawing with JavaFX Canvas or Swing’s Graphics2D
Implementation tips:
- Use JavaFX for smoother graphics and easier scaling transforms.
- Evaluate the function at sampled x-values; for sharp features use adaptive subdivision.
- For interactive features, maintain a camera/viewport state.
8 — History, Scripting & Macros
Goal: Add persistent history, scripting, and macro support to automate sequences of calculations.
Key features:
- Save/load history to disk (JSON or plain text)
- Define macros (e.g., “areaCircle r -> pi * r^2”)
- Support short scripts using a small embedded language or BeanShell / JS engine (Nashorn is deprecated)
Learning outcomes:
- File I/O and serialization
- Design of small DSLs (domain-specific languages)
- Security considerations for executing scripts
9 — Mobile/Responsive Calculator (Cross-platform)
Goal: Target mobile devices or make the UI responsive for different screen sizes.
Options:
- JavaFX with Gluon mobile tools
- Build a backend calculation engine in Java, front-end in Kotlin/Android or Swift/iOS
- Use web technologies (React, Vue) and expose Java calculation engine via a REST service
Learning outcomes:
- Platform-specific UI concerns, cross-compilation
- Separation of concerns between UI and calculation core
10 — Performance & Precision Improvements
Goal: Improve numeric stability, performance, and precision for demanding calculations.
Key features:
- Use BigDecimal for precise decimal arithmetic and rounding modes
- Implement arbitrary-precision libraries (BigInteger, BigDecimal)
- Optimize parser and evaluator (caching parsed expressions)
- Use native libraries (JNI) for heavy numerical tasks if needed
Practical tips:
- Benchmark with JMH for hotspots.
- Cache parsed RPN for repeated evaluations of the same expression.
- Beware BigDecimal’s performance trade-offs — only use when necessary.
11 — Testing, Documentation & Packaging
Goal: Make your calculator production-ready: unit tests, documentation, and distribution.
Tasks:
- Write unit tests using JUnit for parser, evaluator, and edge cases.
- Create integration tests for GUI interactions (use TestFX for JavaFX).
- Document public APIs and provide usage examples.
- Package as an executable JAR, native installer (jlink), or Docker image for server components.
12 — Project Roadmap & Difficulty Levels
- Beginner: Basic Console Calculator, Menu-Driven functions.
- Intermediate: Swing GUI Calculator, Expression Parser (Shunting-yard), Scientific functions.
- Advanced: Graphing Calculator, Programmer’s mode, Precision & Performance.
- Expert: Scripting/macros, mobile ports, plugin architecture, symbolic algebra (CAS features).
Example: Full parser + evaluator (conceptual)
- Tokenize input into numbers, operators, functions, variables.
- Convert to RPN with Shunting-yard.
- Evaluate RPN with a stack supporting functions and variables.
- Cache compiled RPN for repeated evaluation.
Pseudocode (high level):
tokens = tokenize(input) rpn = shuntingYard(tokens) result = evaluateRPN(rpn, variableMap) Learning resources and libraries
- Java standard library: java.lang.Math, BigDecimal, BigInteger
- Apache Commons Math: statistical and special functions
- exp4j, mXparser: expression parsers and evaluators you can learn from or embed
- JavaFX: modern UI for graphics and controls
- JUnit/TestFX: testing frameworks
Final tips
- Start small and iterate: get a working console version, then add a GUI, then parsing, then scientific features.
- Keep UI and calculation core separate so you can reuse the engine across interfaces.
- Write tests for edge cases (divide-by-zero, floating-point precision, malformed input).
- Use existing libraries when appropriate — reinventing complex functions (Gamma, special functions) is rarely necessary unless your goal is learning.
This progression gives you a path from a simple calculator to a powerful scientific and graphing tool, with clear technical skills to practice at each step.
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