java for the beginners
DESCRIPTION
Java is a very fashionable language which is used lately for various purposes such as developing apps for mobile phone, creating interactive parts in a website etc. Many have a liking for this language and many just want to avoid it because its just another platform. How does it feel to program in this language and is it fun?TRANSCRIPT
What are we going to venture !
• The Platform.• Java Virtual Machine.• The Programming Environment.• Some fundamentals (datatypes etc.).• Structure of a Java Program.• Mistakes we make while writing the code.
(c) Biswadip Goswami, [email protected]
The platform
Java is a whole platform !Huge libraryLots of reusable codeExecution environment providing services as • Security• Portability• Automatic garbage collection and more
(c) Biswadip Goswami, [email protected]
The Virtual MachineJVM or Java Virtual Machine. • Platform independent execution environment• Convert ByteCode to machine code• Mimics a real Java processor• The ByteCode is executed regardless of the
Operating System• A ByteCode stream: 03 3b – The mnemonics • iconst_0 // 03• istore_0 // 3b
(c) Biswadip Goswami, [email protected]
JVM and Garbage Collection:JVM stores all objects by the java applications and Garbage Collection is a process of automatically freeing those objects which are not referenced by the program any more.Garbage collector also stops heap fragmentation.
(c) Biswadip Goswami, [email protected]
Some IDEs Available:
• NetBeans [http://www.netbeans.org]• Eclipse [http://www.eclipse.org]• JBuilder 7
[http://www.borland.com/jbuilder]• Oracle9i JDeveloper
[http://www.oracle.com/ip/develop/ids/]
(c) Biswadip Goswami, [email protected]
JARGONS !
• JDK – Java development kit• JRE – Java runtime environment• SE – Standard Edition• EE – Enterprise edition• ME – Micro edition• J2 – Java 2• SDK – Software development kit• Netbeans – there is no acronym sorry !
(c) Biswadip Goswami, [email protected]
(c) Biswadip Goswami, [email protected]
Data Types• Java is a strongly typed language• Eight primitive types in Java• Integer types– int (4bytes)– Short (2bytes)– Long (8bytes)– Byte (1byte)
• Floating point type– Float (4bytes)– Double (8bytes) (c) Biswadip Goswami, [email protected]
• Char type – used to describe individual characters. E.g. - \b (backspace), \t (tab)
• Boolean type – it has two values ‘true’ and ‘false’.
• After declaring a variable, it must be explicitly initialized. E.g. int days=30;
• In java declaration can be done anywhere in the code. E.g. for(int x;x<=10;x++);
(c) Biswadip Goswami, [email protected]
• Console input and output in Java.• Standard output stream (System.out.println)• Standard input stream (System.in)• Methods of Scanner class reads inputs.
• Scanner(System.in)
• nextLine method – input with space• next method – input single string
(c) Biswadip Goswami, [email protected]
The Structure:
Any simple java program looks like<access-specifier> class <class-name>{<access-specifier> static void main(varargs){variables;functions;}}
(c) Biswadip Goswami, [email protected]
Troubleshooting:• Check for upper and lower case of class name
and .java program name.• Bad command or file name - check for installation• Cannot read: xyz.java – check for the file in the
current directory• Error about new language construct – check for the
latest version of JDK• Cannot find the symbol – check for the
name/keywork/identifier• Using an IDE generally saves you from setting of the
CLASSPath. (c) Biswadip Goswami, [email protected]
Thank you !
For assistance with your ASP.Net or JAVA requirements contact:
Biswadip GoswamiPrimary e-mail: [email protected] e-mail: [email protected]:
http://people.cognobytes.com/biswadipSkype me at biswadip.g
(c) Biswadip Goswami, [email protected]