Void Method Code Examples in Java for High School Students

📚 Quick Study Guide: Java Void Methods

• 💡 What is a Void Method? A `void` method in Java is a function that performs a task or an action but does not return any specific value back to the part of the program that called it.
• 📝 Purpose: They are typically used for operations that have a 'side effect,' such as printing information to the console, modifying the state of an object, or saving data to a file. They simply 'do' something.
• ⚙️ Declaration Syntax: You declare a `void` method by using the `void` keyword in its header, replacing where a return type (like `int`, `String`, `boolean`) would normally be. Example: `public static void printGreeting(String name) { ... }`
• 🗣️ Calling a Void Method: To execute a `void` method, you simply call it by its name, followed by parentheses containing any necessary arguments. Example: `printGreeting("Alice");`
• 🧩 Parameters: `void` methods can accept one or more parameters, which are inputs that the method uses to perform its task. These parameters are defined within the parentheses in the method header. Example: `public static void calculateAndDisplaySum(int num1, int num2) { ... }`
• 🚫 No Return Value: Since `void` methods do not return a value, you cannot assign the result of a `void` method call to a variable. Using `return;` inside a `void` method simply exits the method early without returning data.
• ✅ Common Uses: Displaying messages, setting values of properties, performing calculations whose result is directly used within the method (e.g., printed), or initiating processes.

🧠 Practice Quiz: Java Void Methods

Choose the best answer for each question.

1. Which keyword signifies that a Java method does not return a value?
   A) `null`
   B) `empty`
   C) `void`
   D) `nothing`
2. Consider the following Java method declaration:

   public static ____ showDetails(String item, int quantity) {
       System.out.println("Item: " + item + ", Quantity: " + quantity);
   }

   What keyword should fill the blank to correctly define a method that displays information without returning any value?
   A) `String`
   B) `int`
   C) `void`
   D) `boolean`
3. How would you correctly invoke a `void` method named `updateScore` that takes an `int` parameter `points`?
   A) `int newScore = updateScore(100);`
   B) `updateScore(100);`
   C) `System.out.println(updateScore(100));`
   D) `return updateScore(100);`
4. Which statement accurately describes a `void` method in Java?
   A) It must always include a `return` statement with a value.
   B) It cannot accept any parameters.
   C) It executes a sequence of instructions but does not provide an output value to the caller.
   D) It can return `0` or `null` if no specific value is generated.
5. Which of the following is a valid header for a `void` method that takes no arguments?
   A) `public String getInfo()`
   B) `private static void performAction()`
   C) `protected int calculateValue(double input)`
   D) `public boolean checkStatus()`
6. What occurs if you attempt to assign the result of a `void` method call to a variable?
   A) The variable will be assigned `null`.
   B) A compile-time error will be generated.
   C) The variable will hold an empty string.
   D) The program will crash at runtime.
7. For which of the following tasks would a `void` method be the most appropriate choice?
   A) Calculating and returning the average of a list of numbers.
   B) Retrieving a specific record from a database and returning it.
   C) Printing a formatted report to the console.
   D) Checking if a user's password meets complexity requirements and returning `true` or `false`.