A Computer Science Basic Java A Computer Science
A+ Computer Science Basic Java © A+ Computer Science - www. apluscompsci. com
A Simple Class public class Aplus. Comp. Sci { } All Java programs start with a class. © A+ Computer Science - www. apluscompsci. com
A Simple Class + main public class Aplus. Comp. Sci { public static void main(String[] args) { System. out. println("Aplus Comp Sci!"); } } OUTPUT Aplus Comp Sci! © A+ Computer Science - www. apluscompsci. com
![Syntax Rules public class Aplus. Comp. Sci { //open brace public static void main(String[]](http://slidetodoc.com/presentation_image_h2/90edd68d424865b6c2cd94cee7aad89f/image-4.jpg "Syntax Rules public class Aplus. Comp. Sci { //open brace public static void main(String[]")
Syntax Rules public class Aplus. Comp. Sci { //open brace public static void main(String[] args) { System. out. println("Aplus Comp Sci!"); } } //close brace Braces – You gotta have ‘em! Every class and every method must have a { and a }. © A+ Computer Science - www. apluscompsci. com
![Syntax Rules public class Aplus. Comp. Sci { public static void main(String[] args) {](http://slidetodoc.com/presentation_image_h2/90edd68d424865b6c2cd94cee7aad89f/image-5.jpg "Syntax Rules public class Aplus. Comp. Sci { public static void main(String[] args) {")
Syntax Rules public class Aplus. Comp. Sci { public static void main(String[] args) { System. out. println("Aplus Comp Sci!"); } } You must put a semi-colon at the end of all Java program statements ( ; ). © A+ Computer Science - www. apluscompsci. com
Syntax Rules Never put a ; before an open { brace ; { //illegal }; //legal © A+ Computer Science - www. apluscompsci. com
![Indentation public class Aplus. Comp. Sci { public static void main(String[] args) { System.](http://slidetodoc.com/presentation_image_h2/90edd68d424865b6c2cd94cee7aad89f/image-7.jpg "Indentation public class Aplus. Comp. Sci { public static void main(String[] args) { System.")
Indentation public class Aplus. Comp. Sci { public static void main(String[] args) { System. out. println("Aplus Comp Sci!"); } } Indent all code 3 spaces to make it easier to read. © A+ Computer Science - www. apluscompsci. com
apluscompsci. java © A+ Computer Science - www. apluscompsci. com
Basic Java Output © A+ Computer Science - www. apluscompsci. com
System. out frequently used methods Name Use print(x) print x and stay on the current line println(x) print x and move to next line down printf(s, x) print x according to s specifications © A+ Computer Science - www. apluscompsci. com
Basic Java Output reference command / method System. out. print("aplus compsci"); OUTPUT aplus compsci © A+ Computer Science - www. apluscompsci. com
Basic Java Output System. out. print("aplus compsci"); OUTPUT aplus compsci © A+ Computer Science - www. apluscompsci. com
Basic Java Output System. out. println("aplus compsci"); OUTPUT aplus compsci © A+ Computer Science - www. apluscompsci. com
Basic Java Output System. out. println("aplus compsci"); OUTPUT aplus compsci © A+ Computer Science - www. apluscompsci. com
one. java © A+ Computer Science - www. apluscompsci. com
Intermediate Java Output n t r b newline tab carriage return backspace System. out. println("aplusctompsci"); OUTPUT aplusc ompsci © A+ Computer Science - www. apluscompsci. com
Intermediate Java Output n t r b newline tab carriage return backspace System. out. println("apluscomtpsci"); OUTPUT apluscom psci © A+ Computer Science - www. apluscompsci. com
Intermediate Java Output n t r b newline tab carriage return backspace System. out. println("apluscompnsci"); OUTPUT apluscomp sci © A+ Computer Science - www. apluscompsci. com
two. java © A+ Computer Science - www. apluscompsci. com
Intermediate Java Output \ " ’ outs outs " outs ’ System. out. println("aplus\compsci"/"); OUTPUT apluscompsci"/ © A+ Computer Science - www. apluscompsci. com
Intermediate Java Output \ " ’ outs outs " outs ’ System. out. println("aplus\'comp'sci'/"); OUTPUT aplus'comp'sci'/ © A+ Computer Science - www. apluscompsci. com
Escape Sequences frequently used combinations Name Use t tabs over five spaces n moves to front of next line b deletes previous character r moves to front of current line \ nets one backslash " nets one double quote " ’ nets one single quote ’ © A+ Computer Science - www. apluscompsci. com
Basic Java Comments // /* */ single-line comments block comments //this line prints stuff on the screen System. out. println("aplus cs"); © A+ Computer Science - www. apluscompsci. com
Basic Java Comments // /* */ /* single-line comments block comments this line prints stuff on the screen */ System. out. println("aplus cs"); © A+ Computer Science - www. apluscompsci. com
Intermediate Java Output System. out. printf("%s", "apluscsn"); OUTPUT apluscs © A+ Computer Science - www. apluscompsci. com
three. java © A+ Computer Science - www. apluscompsci. com
Advanced Java Output System. out. println( 7 + 8 + 9 ); OUTPUT 24 © A+ Computer Science - www. apluscompsci. com
Advanced Java Output System. out. println( 7 + " " + 8 + 9 ); OUTPUT 7 89 © A+ Computer Science - www. apluscompsci. com
Advanced Java Output System. out. println( 7 + 8 + " " + 9 ); OUTPUT 15 9 © A+ Computer Science - www. apluscompsci. com
four. java © A+ Computer Science - www. apluscompsci. com
Programming Errors Syntax errors occur when you type something in wrong, causing the code to not compile. //missing semicolon - ; expected System. out. println("aplus cs") //case problem – should be System system. out. println("aplus cs") © A+ Computer Science - www. apluscompsci. com
Programming Errors Runtime errors occur when something goes wrong while the program is running. //an out of bounds exception is thrown String s = "runtime_error"; System. out. println( s. char. At(15) ); © A+ Computer Science - www. apluscompsci. com
five. java © A+ Computer Science - www. apluscompsci. com
Work on Programs! Crank Some Code!
A+ Computer Science Basic Java © A+ Computer Science - www. apluscompsci. com
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