Java Tutotrial for [NLP-AI] 2

JavaTutotrial for [NLP-AI]2 ashishfa@cse.iitb.ac.in

asgn1 asgn2 Last Assignment ? Print the details in tabular format - use tabs \t • System.out.println("\"Can we print '\\' with System.out.println() statement?\"" ); Java Tutorial series part 2

Storing data In Java, Data can be stored as • Numbers 2, 6.67, 0.009 • Characters ‘c’, ‘p’, ‘?’, ‘2’ • Strings “data”, “Hindi language”, “$99”, www.rediff.com Java Tutorial series part 2

Program int1 int2 // this program will declare and print a number class int2 { public static void main(String[] arguments) { int weight = 68; System.out.println("your weight is " + weight); } } //end of program Java Tutorial series part 2

Comments(double slash) • Not executed • For documentation • Can be placed on any line • Anything written after // is not executed • E.g. // this is a comment • Used to explain/describe what is done in the program • Good practice Java Tutorial series part 2

Types of numbers float1 • int Whole numbers like 0, 575, -345 etc. • double Numbers with decimal point like 12.453, 3.432, 0.0000002 Java Tutorial series part 2

Variable declaration • Before using any name, it must be declared (with its type i.e int or double). • Needed only once in one program • Generally, done initially • Syntax datatype name; double total; // stores the total value int index; int a,b , c, sum, interest; Java Tutorial series part 2

Assignment int3 int5 int a; //declaration – needed once a = 10 ; // assignment … declared above int a = 10; // assignment and declaration together 10 = a ; // not possible – compilation error Left hand side is always a variable for assignment Storage area a 10 Java Tutorial series part 2

int4 Assignment… int a , b ; a = 4; b = 7; a = b; b = a; a = 5; // a =? b = ? // a = 4 b = ? // a = 4 b = 7 // a = 7 b = 7 // a = 7 b = 7 // a = 5 b = 7 Java Tutorial series part 2

Character data char1 char2 • Characters ‘a’, ‘A’, ‘c’ , ‘?’ , ‘3’ , ‘ ’ (last is the single space) • Enclosed in single quotes • Character variable declaration char ch; • Character assignment ch = ‘k’; Java Tutorial series part 2

string1 string2 string3 String data • Strings are sequence of characters enclosed in double quotes • Declaration String name; String address; String line; • Assignment name = “ram”; line = “this is a line with spaces”; name = “a”; // single character can be stored name = “”; // empty string • The sequence of characters enclosed in double quotes, printed in println() are also strings. • E.g. System.out.println( “Welcome ! “ ); Java Tutorial series part 2

Practice problem • Try to print these two figures on the screen using println and least number of strings ******* ***** *** * *** ***** ******* ********** * * * * * * ********** Java Tutorial series part 2

Essential Linux commands • Use tukaram(10.144.22.105) or any other linux machine • Type javac and java, to verify if java is installed and working properly. • Login to tukaram [ashish@tukaramlec2]$ • Create folder (directory) mkdir <foldername> • Goto that folder cd <foldername> cd - To use or work into the folder • Remove a folder rmdir <foldername> • list all file in the folder ls Java Tutorial series part 2

Vi (Vim) • Vi is notepad of Linux. • Used to write programs • Works in 2 modes • Command mode - While in vi, press escape to go to command mode • Edit mode - while in vi, if you are in command mode, press ‘i’ on keyboard once to go to edit mode . Java Tutorial series part 2

Vi … vi <filename> • To create a new file or existing file. e.g. vi int1.java • Before start typing, press ‘i’ to goto edit mode and type the program. • To save program Press escape and then these 2 characters “:w” • To save and quit vi Press escape and then these 3 characters “:wq” • To quit vi without saving the latest changes Press escape and then these 3 characters “:q!” Java Tutorial series part 2

Essential Linux commands rm <filename> • This command deletes the file specified e.g. rm int1.class • To log out press ‘ctrl-D’ at command prompt • javac , java Java Tutorial series part 2

Thank you  Java Tutorial series part 2

Java Tutotrial for [NLP-AI] 2