METHODS - Introduction to Java Programming: Comprehensive Version - page 233

C HAPTER S UMMARY
1.

Making programs modular and reusable is one of the central goals in software engineer-
ing. Java provides many powerful constructs that help to achieve this goal. Methods are
one such construct.

2.

The method header specifies the modifiers , return value type , method name , and param-
eters of the method. The static modifier is used for all the methods in this chapter.

3.

A method may return a value. The returnValueType is the data type of the value the
method returns. If the method does not return a value, the returnValueType is the
keyword void .

4.

The parameter list refers to the type, order, and number of a method's parameters. The
method name and the parameter list together constitute the method signature. Param-
eters are optional; that is, a method doesn't need to contain any parameters.

5.

A return statement can also be used in a void method for terminating the method and
returning to the method's caller. This is useful occasionally for circumventing the nor-
mal flow of control in a method.

6.

The arguments that are passed to a method should have the same number, type, and
order as the parameters in the method signature.

7.

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.

8. A value-returning method can also be invoked as a statement in Java. In this case, the
caller simply ignores the return value.

9.

A method can be overloaded. This means that two methods can have the same name, as
long as their method parameter lists differ.

10.

A variable declared in a method is called a local variable. The scope of a local variable
starts from its declaration and continues to the end of the block that contains the vari-
able. A local variable must be declared and initialized before it is used.

11.

Method abstraction is achieved by separating the use of a method from its implementa-
tion. The client can use a method without knowing how it is implemented. The details
of the implementation are encapsulated in the method and hidden from the client who
invokes the method. This is known as information hiding or encapsulation.

12.

Method abstraction modularizes programs in a neat, hierarchical manner. Programs
written as collections of concise methods are easier to write, debug, maintain, and
modify than would otherwise be the case. This writing style also promotes method
reusability.

13.

When implementing a large program, use the top-down and/or bottom-up coding
approach. Do not write the entire program at once. This approach may seem to take
more time for coding (because you are repeatedly compiling and running the program),
but it actually saves time and makes debugging easier.