Java Reference
In-Depth Information
er is an array of
String
objects, referred to by the name
args
. Arrays
of objects are denoted by the square brackets
[]
that follow the type
name. In this case
args
will contain the program's arguments from the
command line with which it was invoked. Arrays and strings are covered
later in this chapter. The meaning of
args
for the
main
method is de-
The name of a method together with its parameter list constitute the
signature
of the method. The signature and any modifiers (such as
pub-
lic
and
static
), the return type, and exception throws list (covered later
in this chapter) form the method
header.
A method
declaration
consists
of the method header followed by the method
body
a block of statements
appearing between curly braces.
In this example, the body of
main
contains a single statement that in-
vokes the
println
methodthe semicolon ends the statement. A method
is invoked by supplying an object reference (in this case
System.out
the
out
field of the
System
class) and a method name (
println
) separated by
a dot (
.
).
HelloWorld
uses the
out
object's
println
method to print a newline-ter-
minated string on the standard output stream. The string printed is the
string literal
"Hello,world"
, which is passed as an argument to
println
. A
string literal is a sequence of characters contained within double-quotes
"
and
"
.
Exercise 1.1
: Enter, compile, and run
HelloWorld
on your system.
Exercise 1.2
: Try changing parts of
HelloWorld
and see what errors you
might get.
