{Java Technology “Hello, World!” Dr. Sergey Krylov

{Java Technology “Hello, World!” Dr. Sergey Krylov

Start and finish Break Facilities, telephones and messages Questions and discussions LOGISTICS

BASICSQ. What is a program? Ans. A sequence of instructions that a computer can interpret and execute. Q. Why Java and not Hindi / Marathi / English? Ans. Since, so far , computer is not intelligent enough to understand natural languages.

PROGRAMMING Task definition Making of Algorithm, Writing Code Compilation, Execution

TO MAKE PROGRAM Step 1: Source Code Step 2: Compiling Step 3: Load into device Step 4: Execute

TOOLS 1) Code editor 2) Compiler 3) Execution environment 4) Debugger

ECLIPSE START Remember the location in the field! Workspace – project files location.

PROJECT AND CLASS File New Java Project⇒ ⇒ File New Class⇒ ⇒

ECLIPSE INTERFACE Right click to add class Write source code Compile errors Executio n output. Right click to locate file

CLASSClass definition Method body public class Program 1 { public static void main (String[] args) { } }

JAVA PROJECT Klass_1 Klass_2 Klass_N… method 1 method 2 method K … field 1 field 2 field. M …Import Klass_G

HELLO, WORLD class import java. io. Print. Stream; public class Program 1 { public static Print. Stream out = System. out; public static void main (String[] args) { out. println(“Hello, World!”); } }create object method call

HELLO, WORLD 13 import java. io. Print. Stream; public class Program 1 { public static Print. Stream out = System. out; public static void main(String[] args) { out. println(«Hello, world!»); } } Standard Java class. Name is equal to source file name Start Eclipse and write the program The first method to run Path to find needed classes Create output object

Compiling: is the process of translating source code written in a particular programming language into computer-readable machine code that can be executed. $ javac First. java This command will produce a file ‘First. class’, which is used for running the program with the command ‘java’. Running: is the process of executing program on a computer. $ java First COMPILING AND RUNNING Eclipse ->>>

CONSOLE OUTPUT

PRINTING ON THE SCREEN 1. System. out. println(“Hello World”); – outputs the string “Hello World” followed by a new line on the screen. 2. System. out. print(“Hello World”); — outputs the string “Hello World” on the screen. This string is not followed by a new line. 3. Some Escape Sequence – • \n – stands for new line character • \t – stands for tab character

TIPS ON PROGRAMMING • Some common errors in the initial phase of learning programming: — Mismatch of parentheses — Missing ‘; ’ at the end of statement — Case sensitivity • The best way to learn programming is writing a lot of programs on your own.

Write a program that prints three lines of text. HOMEWORK

Thinking in Java (http: //www. mindviewinc. com/Books/downloads. h tml) – Bruce Eckel Richard G Baldwin’s “Introductory Java Programming Tutorial” on: http: //www. dickbaldwin. com/tocint. htm REFERENCES

QUESTIONS?