Defining Classes I - Java - page 171

then the method always returns a value of type double , and the heading

public String yourMethod()

indicates a method that always returns a value of type String .
The following is a void method heading:

public void ourMethod()

Notice that when the method returns no value at all, we use the keyword void in place
of a type. If you think of void as meaning “no returned type,” the word void begins to
make sense.
An invocation of a method that returns a value can be used as an expression any-
place that a value of the Type_Returned can be used. For example, suppose anObject is
an object of a class with methods having our sample heading; in that case, the follow-
ing are legal:

invocation

double d = anObject.myMethod();
String aStringVariable = anObject.yourMethod();

A void method does not return a value, but simply performs an action, so an invo-
cation of a void method is a statement. A void method is invoked as in the following
example:

anObject.ourMethod();

Note the ending semicolon.
So far, we have avoided the topic of parameter lists by only giving examples with
empty parameter lists, but note that parentheses are required even for an empty
parameter list. Parameter lists are discussed later in this chapter.
The body of a void method definition is simply a list of declarations and state-
ments enclosed in a pair of braces, {} . For example, the following is a complete void
method definition:

body

public void ourMethod()
{
System.out.println("Hello");
System.out.println("from our method.");
}

The body of a method that returns a value is the same as the body of a void method
but with one additional requirement. The body of a method that returns a value must
contain at least one return statement. A return statement is of the form

return
statement

return Expression ;