Displaying Output

1
Displaying Output

• An output stream sends data to an output device.
  
• To process data for the output stream, Java
  provides the System (this class is in the
  java.lang package) class with methods for
  displaying output.
• To display output on the screen, use System.out
• out has 2 methods
• print() displays data and leaves the cursor at
  the end of the output
• println() displays data and moves cursor to
  next line
• both methods require arguments (data passed to a
  method for processing)

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Example System.out.print(Java
Rocks) System.out.println(the
House) System.out.println(2005) Output
Java Rocksthe House 2005
String Arguments set of characters enclosed in
quotes.
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Escape Sequence (a backslash \ followed by a
symbol to represent a character)
\n newline \t tab (8 spaces) \\ backslash \ doubl
e quotes
Example System.out.print(Java
Rocks\t) System.out.println(the
House) System.out.println(2005) Output J
ava Rocks the House 2005
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Formatting Output
Format() method can be used in place of the
print() and println() methods to control output.
This is a new method for Java! Format string
specifier takes the form alignmentwidths
indicates the start of a specifier alignment s
kip for right alignment minus sign for left
alignment width the number of characters to
use for output s indicates the argument is a
string (we will look at numeric formatting
later) If width is greater than the number of
characters in the argument then spaces pad the
output. If a string is longer than width,
strings to the right are moved over. Example Sys
tem.out.format (-15s 30, Class,
Average\n) System.out.format (-15s 30,
English, 95\n) System.out.format (-15s
30, History, 86\n)
5
Text can also be included in the format
string Example System.out.format (My averages
are -8s 8, 95, 86\n)
6
Code Conventions (aka rules to code/live/pass
this course by)

• Begin all programs with introductory comments
  which include your name, class name, date
  completed and purpose of program
• Package names begin with a lowercase letter and
  then uppercase letter for each word within the
  name. No spaces! example - firstApplication
• Class names should be nouns and begin with an
  uppercase letter and then uppercase letter for
  each for each word within the name. No spaces!
  example - GreetingMessage
• A comment block should be included before each
  class and method (except the main() method).
• Comment should not reiterate what is obvious in
  code.
• Indent statements within a method.
• An open curly brace should be placed on the
  same line as the class or method declaration, and
  the closing curly brace should be on a separate
  line and aligned with the class or method
  declaration.

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• Lab AboutMe
• Parts 1 and 2, pages 64 and 65
• Follow output format guidelines carefully
• Turn in code listing and screen shot
• Good Luck!!