Java Reference
In-Depth Information
Car yourCar = new Car("Mazda", "RX-8", 2);
Listing2-9 declaresaninstancemethodnamed printDetails() .Byconvention,
amethod'sname begins with alowercase letter,andthe first letter ofeach subsequent
word in a multiword method name is capitalized.
theseparameterswhenyoucallthemethod.Because printDetails() doesnottake
arguments, its parameter list is empty.
Note Amethod'snameandthenumber,types,andorderofitsparametersareknown
as its signature .
When a method is invoked, the code within its body is executed. In the case of
printDetails() , this method's body executes a sequence of Sys-
tem.out.println() method calls to output the values of its make , model , and
numDoors instance fields.
Unlike constructors, methods are declared to have return types. A return type iden-
tifies the kind of values returned by the method (e.g., int count() returns 32-bit
integers). If a method does not return a value (and printDetails() does not), its
return type is replaced with keyword void , as in void printDetails() .
Note Constructors don't have return types because they cannot return values. If a
constructor could return an arbitrary value, how would that value be returned? After
all,the new operatorreturnsareferencetoanobject,andhowcould new alsoreturna
constructor value?
the object's reference and the right operand specifies the method to be called. For ex-
ample, the myCar.printDetails() and yourCar.printDetails() expres-
sions invoke the printDetails() instance method on the myCar and yourCar
Compile Listing 2-9 ( javac ) and run this application ( java Car ).
You should observe the following output, whose different instance field values prove
that printDetails() associates with an object:
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