Methods in Java

A Java method is a collection of statements that are grouped together to perform an operation. When you call the System.out.println method, for example, the system actually executes several statements in order to display a message on the console.

Now you will learn how to create your own methods with or without return values, invoke a method with or without parameters, overload methods using the same names, and apply method abstraction in the program design.

Creating a Method:

In general, a method has the following syntax:

modifier returnValueType methodName(list of parameters) {
 // Method body;
}

A method definition consists of a method header and a method body. Here are all the parts of a method:
 

• Modifiers: The modifier, which is optional, tells the compiler how to call the method. This defines the access type of the method.
• Return Type: A method may return a value. The returnValueType is the data type of the value the method returns. Some methods perform the desired operations without returning a value. In this case, the returnValueType is the keyword void.
• Method Name: This is the actual name of the method. The method name and the parameter list together constitute the method signature.
• Parameters: A parameter is like a placeholder. When a method is invoked, you pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a method. Parameters are optional; that is, a method may contain no parameters.
• Method Body: The method body contains a collection of statements that define what the method does.

Calling a Method:

In creating a method, you give a definition of what the method is to do. To use a method, you have to call or invoke it. There are two ways to call a method; the choice is based on whether the method returns a value or not.

When a program calls a method, program control is transferred to the called method. A called method returns control to the caller when its return statement is executed or when its method-ending closing brace is reached.

If the method returns a value, a call to the method is usually treated as a value. For example:
 

int larger = max(30, 40);

If the method returns void, a call to the method must be a statement. For example, the method println returns void. The following call is a statement:
 

System.out.println("Welcome to Java!");