Introduction to Java Thanks to Dan Lunney (SHS)

Java Basics File names The “main” method Output to screen Escape Sequence – Special Characters format() method Conventions

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… }

The “main” method Executes the main section of code All other methods “called” from here Syntax for main method is: public static void main(String[] args) { code in here… }

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

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

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 it’s a string

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.