JAVA PROGRAM • LEVEL 08 — METHODS & RECURSION
Sum Natural Numbers Recursively in Java
Learn sum natural numbers recursively in java with a complete, compiler-ready Java 17 example.
PROBLEM UNDERSTANDING
Input and expected output
No input required
55
COMPLETE JAVA 17 PROGRAM
Complete Java 17 implementation
class Main {
static int sum(int n) { return n==0?0:n+sum(n-1); }
public static void main(String[] args) {
System.out.println(sum(10));
}
}CURRENT STEP
Select Start to walk through the important lines.
SELECTED LINE
No line selected
EXPECTED OUTPUT FOR THE SAMPLE
55
PROGRAM EXPLANATION
Algorithm and explanation
- Initialize the deterministic sample values used for sum natural numbers recursively in java.
- Apply Recursion and Reduction in the order shown by the program.
- Print the final result and compare it with the documented sample output.
This Java 17 example demonstrates Recursion and Reduction through a complete, executable program. The values are intentionally small so students can trace each statement, verify the output, and then modify the example safely in the online compiler.
EFFICIENCY
Time and space complexity
O(n)
O(n)
DEBUGGING CHECKLIST
Common mistakes
Keep the class name Main and the entry method signature public static void main(String[] args) when using the online compiler.
Use Recursion with compatible Java types; Java checks types and method signatures at compile time.
Java is case-sensitive, and every statement that requires a semicolon must end with one.