You want your program to write to the standard output.
Again despite Rusty’s quote, there are circumstances (such as a
server program with no connection back to the
terminal) in which
can become a very important debugging tool (assuming that you can
find out what file the server program has redirected standard output
into; see Section 9.7).
System.out is a
so in every introductory text you see a program containing this line,
or one like it:
System.out.println("Hello World of Java");
println method is
there are forms of it for
Object (which obviously
calls the given object’s
String, and for each of the base
boolean, etc.). Each takes only one argument, so
it is common to use string
System.out.println("The answer is " + myAnswer + " at this time.");
Remember that string concatenation is also polymorphic: you can “add” anything at all to a string, and the result is a string.
Up to here I have been using a
System.out. What if you want to use a
class has all the same methods as
PrintStream and a constructor that takes a
Stream, so you can just say:
PrintWriter pw = new PrintWriter(System.out); pw.println("The answer is " + myAnswer + " at this time.");
One caveat with this string concatenation is that if you are appending a bunch of things, and a number and a character come togetherat ...