Aprenda Method Declaration and Invocation

Declaring Your Own Methods in Java

To create your own method in Java, you need to follow a specific syntax and set of rules. A method is a block of code that performs a specific task and can be called from other parts of your program. Every method declaration includes several key components:

Access modifier: defines the visibility of the method, such as public or private;
Return type: specifies the type of value the method will return (use void if nothing is returned);
Method name: must follow Java naming conventions—start with a lowercase letter and use camelCase;
Parameter list: enclosed in parentheses; can be empty or contain one or more parameters separated by commas;
Method body: the block of code inside curly braces {} that defines what the method does.

General syntax:

accessModifier returnType methodName(parameterList) {
    // method body
}

Example:

public void greetUser() {
    System.out.println("Hello, user!");
}

This method is named greetUser, is declared as public, has no return type (uses void), and doesn't take any parameters. When you call this method, it simply prints a greeting message to the console.

Note

You'll learn about method parameters a little later.

Rules for method declaration:

Method names must be unique within the same class (except for overloading);
Parameter types and order must be clearly defined;
The return type must match the value returned in the method body;
If the method does not return a value, use void as the return type.

Declaring methods helps you organize your code, avoid repetition, and make your programs easier to read and maintain.

Invoking a Method in Java

To use a method in Java, you must invoke (call) it from another method. Most commonly, you will call methods from the main method or from other methods within your class.

Syntax for Method Invocation

To invoke a method, use the following syntax:

Type the method name;
Add parentheses () after the name;
End the statement with a semicolon.

If the method returns a value, you can use it directly or assign it to a variable.

Main.java


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package com.example;

public class Main {
    // Step 1: Declare a method named greet
    public static void greet() {
        // Step 2: Print a greeting message
        System.out.println("Hello from the greet method!");
    }

    public static void main(String[] args) {
        // Step 3: Invoke the greet method
        greet();
    }
}

Methods are invoked using their name followed by parentheses;
You can call a method from main or from any other method in the same class;
If the method returns a value, you can assign it to a variable or use it in an expression.

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