Introduction to Java

1
Introduction to Java

• Thanks to
• Dan Lunney (SHS)

2
Java Basics

• File names
• The main method
• Output to screen
• Escape Sequence Special Characters
• format() method
• Conventions

3
File Names

• In JCreator the file name and class name must be
  identical
• Always start class names with a capital letter
• If more than one word in file name all names are
  capitalized
• Always begin java programs with
• public class FileName
• Code goes here

4
The main method

• Executes the main section of code
• All other methods called from here
• Syntax for main method ispublic static void
  main(String args) code in here

5
Output to Screen

• To print to screen we use the line
  System.out.println()
• What ever is in the () will print
• Text must be in marks
• There are two options
• println prints a line and the enters to start
  new line
• print prints line and remains on same line
• Example System.out.println(Hello class)
  prints Hello class on the screen

6
Escape Sequence Special Characters

• By including special characters within the quote
  marks, java will perform special formatting
• \n new line
• \t tab (8 spaces)
• \\ - backslash
• \ double quote mark
• Example System.out.print(Hello\t)
  System.out.print(class)prints Hello
  class

7
format() method

• Can format the look of text
• Example
• System.out.format(-10s -8s, Hello,
  class)
• Prints Hello class (5 spaces between)
• Symbols
• - indicates start of format
• - indicates left align (nothing for right
  align)
• indicates how many spaces for text
• S indicates its a string

8
Java Conventions

• Always use in an introductory comment with name,
  date, and project
• All class names start with Upper case letters
• Comments should be included before all methods to
  explain them
• All code statements should be indented from
  method line
• Place starting curly brace on the same line as
  classes and methods. Place the ending curly brace
  on its own line with nothing else.