Download - Java for the Beginners
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
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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]
