# 1.9 Method Signatures

**LO 1.9.A** — Identify the correct method to call based on documentation and method signatures.

* **1.9.A.1** — A **method** is a named block of code that only runs when it is called. A **block of code** is any section of code that is enclosed in braces. **Procedural abstraction** allows a programmer to use a method by knowing what the method does even if they do not know how the method was written.
* **1.9.A.2** — A **parameter** is a variable declared in the header of a method or constructor and can be used inside the body of the method. This allows values or arguments to be passed and used by a method or constructor. A **method signature** for a method with parameters consists of the method name and the ordered list of parameter types. A method signature for a method without parameters consists of the method name and an empty parameter list.

**LO 1.9.B** — Describe how to call methods.

* **1.9.B.1** — A **void method** does not have a return value and is therefore not called as part of an expression.
* **1.9.B.2** — A **non-void method** returns a value that is the same type as the return type in the header. To use the return value when calling a non-void method, it must be stored in a variable or used as part of an expression.
* **1.9.B.3** — An **argument** is a value that is passed into a method when the method is called. The arguments passed to a method must be compatible in number and order with the types identified in the parameter list of the method signature. When calling methods, arguments are passed using **call by value**. Call by value initializes the parameters with copies of the arguments.
* **1.9.B.4** — Methods are said to be **overloaded** when there are multiple methods with the same name but different signatures.
* **1.9.B.5** — A method call interrupts the sequential execution of statements, causing the program to first execute the statements in the method before continuing. Once the last statement in the method has been executed or a return statement is executed, the flow of control is returned to the point immediately following where the method was called.