Beginner 20 min read

Writing Your First Method

By the end of this lesson, you'll be able to:

Write a simple method with no parameters and no return value
Call a method from elsewhere in a class
Explain what void means as a return type

Prerequisites: "What Is a Method?"

A method that does something, returns nothing

public void greetCustomer() {
    System.debug('Welcome to the store!');
}

public void greetCustomer() { — void as the return type means "this method performs an action but doesn't hand back a value." No parameters either — empty ( ).
System.debug('Welcome to the store!'); — the action this method performs.
} — closes the method.

Calling it looks like this:

greetCustomer();

greetCustomer(); — notice there's nothing to store the result in — because there is no result, just an action.

A real business example: Hospitality (Front Desk)

public void logCheckIn(String guestName) {
    System.debug(guestName + ' checked in at ' + System.now());
}

logCheckIn('J. Ndlovu');
logCheckIn('T. Adebayo');

public void logCheckIn(String guestName) { — takes one parameter, the guest's name.
System.debug(guestName + ' checked in at ' + System.now()); — logs the guest's name along with the current moment.
} — closes the method.
(blank line)
logCheckIn('J. Ndlovu'); — calls it for the first guest.
logCheckIn('T. Adebayo'); — calls it again for a second guest, same method, different argument.

A hotel's front-desk system logs every check-in the same way — one method, called once per guest, instead of writing out the same System.debug line by hand for every arrival.

Common mistakes

Forgetting the parentheses when calling a method. Writing greetCustomer; instead of greetCustomer(); doesn't call the method at all — it's simply invalid.
Trying to store the result of a void method. String x = greetCustomer(); is a compile error — there's no value to store.

Exercise

Write a void method called logShift that debugs "Shift started." Then call it once.

Show hint

public void logShift() { System.debug('Shift started.'); }

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APEX

Execution Results

Run your code to see the result.

Writing Your First Method Quiz

1. What does void mean as a method's return type?

The method performs an action but returns no value The method always returns null The method has no parameters The method can never be called

Leaderboard

1. Monde Masiza 1/1

My Notes

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Summary

This lesson writes and calls a real method for the first time — the simplest possible shape, one that does something but doesn't hand back a value.

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