- 01Getting Started
- 02Your First Output (System.out.println)
- 03Working with Variables
- 04Conditionals (if statements)
- 05Loops (for statements)
- 06Writing a Method (Function)
- 07Working with Arrays
- 08Loops (while statements)
- 09Classes (Object-Oriented Programming)
- 10Error Handling (try-catch)
- 11Sorting an Array
- 12Recursive Functions
- 13Using the Standard Library
- 14The switch Statement
- 15The Ternary Operator
- 16Inheritance (Extending a Class)
- 17Writing Comments
- 18Logical Operators (&&, ||, !)
- 19Constants (final)
- 20Splitting and Joining Strings (split, join)
- 21Writing Null-Safe Code
- 22Searching a Collection (contains)
- 23Transforming an Array (Stream map)
- 24Two-Dimensional Arrays (Tabular Data)
- 25Writing a Custom Exception Class
- 26Method Overloading
- 27Working with HashSet (Sets)
- 28Checking Correctness with assert (Your First Step into Testing)
- 29Higher-Order Functions (Passing a Function as an Argument)
- 30Stacks and Queues (Basic Data Structures)
- 31Type Conversion (Casting) Basics
- 32Intro to Regular Expressions (Pattern Matching)
- 33The Binary Search Algorithm
- 34Building a Caesar Cipher (a Character-Shifting Cipher)
- 35Understanding How Bubble Sort Works
- 36Building and Displaying Dates (Basic Year/Month/Day Operations)
- 37Writing Multiple Test Cases Together
- 38Speeding Up Calculations with Memoization (Caching)
- 39Normalizing Strings (trim, Unifying Case)
- 40Shallow Copy vs. Deep Copy
- 41Enum (Enumerated Types) Basics
- 42Flattening a List
- 43Reversing a String and Checking for Palindromes
- 44Pairing Up Two Lists (the zip operation)
- 45Rounding Numbers (floor, ceil, round)
- 46Multi-Line Strings (Text Blocks)
- 47Functions That Return Multiple Values (record)
- 48Finding the GCD and LCM (the Euclidean Algorithm)
- 49Formatting Numbers (Padding Digits, Decimal Places)
- 50Cleanup Logic with try/catch/finally
- 51Writing Generic Functions
- 52File Reading and Writing Basics
- 53Generating Random Numbers
- 54Bitwise Operators (AND, OR, XOR, shifts)
- 55Reading Command-Line Arguments
- 56Waiting for a Fixed Amount of Time (Thread.sleep)
- 57Watch Out for Floating-Point Rounding Errors
- 58Reading from Standard Input
- 59FizzBuzz (the Classic Practice Problem)
- 60Checking Whether a Number Is Prime
- 61Set Operations (Union, Intersection, Difference)
- 62Converting Number Bases (Binary, Hex)
- 63Checking Balanced Parentheses (an Application of Stacks)
- 64Checking Whether Two Words Are Anagrams
- 65Checking Whether a Year Is a Leap Year
- 66Converting Temperature (Celsius to Fahrenheit)
- 67Prime Factorization
- 68[Applied] Build a Simple Inventory Management Tool
Recursive Functions
This lesson covers writing a recursive function in Java, so you understand the mechanism of a function calling itself. It's for anyone searching "Java recursive function usage."
A recursive function is a function that calls itself. It's well-suited to logic that repeats the same calculation pattern, like "n! = n ร (n-1)!".
The example's factorial method calls itself as n * factorial(n - 1), computing the factorial of 5. The base case, if (n <= 1) return 1;, ensures the chain of calls eventually stops.
A common early mistake is forgetting the base case. Without one, the function calls itself forever, and the program crashes abnormally (a StackOverflowError).
In real projects, recursion that's too deep consumes a lot of stack space, so it's worth considering whether the logic could be rewritten as a loop instead.
๐งช This site can't compile or run Java directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser โ nothing is sent anywhere).