Method Overloading
By the end of this lesson, you'll be able to:
- Define method overloading
- Write two overloaded versions of the same method name
- Explain how Apex decides which overload to call
Prerequisites: "Return Values"
Same name, different parameters
public Decimal calculateArea(Decimal side) {
return side * side; // square
}
public Decimal calculateArea(Decimal length, Decimal width) {
return length * width; // rectangle
}Both methods are named calculateArea, but one takes a single Decimal and the other takes two. Apex tells them apart by their parameter list — this is called overloading.
Apex picks the right one for you
Decimal squareArea = calculateArea(5); // calls the one-parameter version → 25
Decimal rectArea = calculateArea(4, 6); // calls the two-parameter version → 24You don't have to name them calculateSquareArea and calculateRectangleArea — Apex matches each call to the overload whose parameter list fits, based purely on how many arguments (and of what type) you pass.
A real business example: Subscription Billing
public Decimal calculatePrice(Decimal monthlyRate) {
return monthlyRate;
}
public Decimal calculatePrice(Decimal monthlyRate, Integer months) {
return monthlyRate * months;
}
Decimal oneMonth = calculatePrice(299); // 299
Decimal sixMonths = calculatePrice(299, 6); // 1794A billing system naturally has both a "price this month" and a "price for N months" calculation — overloading lets both live under one intuitive name instead of two awkwardly different ones.
What does NOT make a valid overload
Changing only the return type while keeping the same parameter list is not a valid overload — Apex (like most languages) can't tell two methods apart based on return type alone, since the call site doesn't always make the return type obvious.
Exercise
Write two overloaded versions of a method named formatName: one that takes just a String fullName and returns it as-is, and one that takes a String firstName and a String lastName and returns them combined with a space.
Show hint
The two versions differ by parameter count.
Method Overloading Quiz
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Summary
Overloading lets several methods share the same name as long as their parameter lists differ — Apex picks the right one automatically based on what you pass in.