Java
Your first function
A practical reference with examples you can run.
Introduction
A function packages a useful operation under a name. Parameters supply input, and a return value carries the result back to the caller. Keep printing separate from calculation so you can reuse and test the function.
Syntax & example
public class Main {
public static void main(String[] args) {
System.out.println(doubleNumber(7));
}
static int doubleNumber(int number) { return number * 2; }
}Expected output
14
Common mistakes
- Using a variable before assigning a value to it.
- Mixing text and numbers without converting deliberately.
- Skipping an empty input or a boundary value when testing.
Practice
Write a function that doubles its input.
Main.javaYour ideas, in code.
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