#AP Computer Science A: Non-Void Methods - The Night Before

Hey there! Let's get you feeling confident about non-void methods. Think of this as your quick-reference guide, designed to make everything click right before the exam. We're going to make sure you know exactly what to expect and how to tackle it.

#Understanding Non-Void Methods: The Core Concept

Non-void methods are all about getting a value back. Unlike void methods that just do something, non-void methods calculate or retrieve a value and then return it for use elsewhere in your program. This returned value can be a primitive type (like int, double, boolean) or a reference type (like String or other objects).

#Method Header Structure

java
public (static) dataType methodName(parameterListOptional)

• public: Access modifier (we'll dive deeper into these later).
• static: Optional keyword; indicates the method belongs to the class itself, not an object (more on this in Unit 5).
• dataType: Crucial! This is the type of value the method will return. It must match the type of the returned expression.
• methodName: How you'll call the method.
• parameterListOptional: Input values the method needs to do its job (optional).

#Returning Different Data Types

#Returning Integers/Doubles

These methods are your math wizards. They perform calculations and return the result. The return statement is key here. It stops the method's execution and sends the calculated value back to the caller.

java
public static double rectanglePerimeter(double length, double width) {
    return 2 * (length + width); // Returns a double
    // Any code after this return statement will be unreachable!
}

#Returning Booleans

Boolean methods are your condition checkers. They evaluate a boolean expression and return true or false. The naming convention isCondition() ...