Why Java?

1
Why Java?

• A brief introduction to Java and its features

Prepared by Mithat Konar
2
Java is

• A general purpose, high-level programming
  language with support for object-oriented
  programming.
• A collection of wide-ranging application
  programming interfaces (APIs).
• A self-contained runtime system.
• A complete set of development tools.

3
Java is not

• An internet-only programming language.
• Difficult.
• JavaScript.

4
Javas Main Features

• Uses virtual machine model to assure true write
  once, run anywhere programs.
• Built-in support for GUIs.
• Built-in networking.
• Built-in security features.
• Built-in support for multi-threaded programming.
• Self-documenting.

5
Java applications

• Applets
• Stand-alone programs
• Network servers
• Network clients
• Embedded designs
• Mobile telephones
• Portable Digital Assistants (PDAs)
• Set-top boxes
• Digital Signal Processing (DSP)

6
Java Virtual Machine

• The conventional compiled-code model

source code
compiler/linker
object code (native)
object code
Microprocessor system
7
Java Virtual Machine

• The virtual machine model

source code
compiler/linker
bytecode
bytecode
Java Virtual Machine
Microprocessor system
8
Java Virtual MachineAdvantages

• Compiled bytecode can run without modification on
  any platform that has a Java Virtual Machine.
• Compile once, run anywhere.

9
Java Virtual Machine Disadvantages

• Compiled bytecode runs a little slower than
  conventional compiled code.
• Advances in JVM technology are closing the gap.
• Not all low-level system manipulations are
  available through standard Java APIs.
• Low-level system manipulations are available in
  the form of native (non-Java) extensions.

10
Java Language Features

• Syntax is similar to C.
• Full support for OOP
• Classes and objects
• Information hiding/access control
• Inheritance, method overriding
• Polymorphism
• Abstract methods and classes
• Interfaces

11
Java Language Features

• Everything that is not a primitive is an object.
• No pointers! Objects are accessed through
  reference variables.
• Built-in memory management and garbage collection.

12
Java API Features

• Support for the essentials
• Classes and objects
• I/O
• Threads
• Applet support
• Conventions used by applets

13
Java API Features

• Graphic User Interface (GUI) support
• Abstract Windowing Toolkit (AWT)
• Windows, dialogs, file dialogs
• Buttons, checkboxes
• Menus, menu bars
• Scrollbars
• etc.
• New generation GUI toolkit Swing
• All the above, plus...
• Platform independent and run-time changeable
  look-and-feel.
• And more.

14
Java API Features

• Networking
• TCP/IP
• UDP
• URLs
• Internationalization
• Programs can automatically adapt to specific
  locales and be displayed in the appropriate
  language.

15
Java API Features

• Security
• Electronic signatures
• Public and private key management
• Access control
• Certificates
• Java Database Connectivity (JDBCTM)
• Provides uniform access to a wide range of
  relational databases.

16
Java API Features

• The Java platform also has APIs for
• 2D and 3D graphics
• Accessibility
• Servers
• Collaboration
• Telephony
• Speech
• Animation
• and more.

17
Benefits of Programming in Java

• Get started quicklyAlthough the Java programming
  language is a powerful object-oriented language,
  it's easy to learn, especially for programmers
  already familiar with C or C.
• Write less codeComparisons of program metrics
  suggest that a program written in the Java
  programming language can be four times smaller
  than the same program in C.

18
Benefits of Programming in Java

• Write better code
• The Java programming language encourages good
  coding practices.
• Garbage collection helps you avoid memory leaks.
• Its object orientation and wide-ranging, easily
  extendible API let you reuse other people's
  tested code and introduce fewer bugs.

19
Benefits of Programming in Java

• Develop programs fasterDevelopment time may be
  as much as twice as fast compared to writing the
  same program in C because you write fewer lines
  of code and it is a simpler programming language
  than C.

20
Benefits of Programming in Java

• Avoid platform dependencies.You can keep your
  program portable by avoiding the use of libraries
  written in other languages and native methods.
• Write once, run anywhere.Because 100 pure Java
  programs are compiled into machine-independent
  bytecodes, they run consistently on any Java
  platform.

21
Benefits of Programming in Java

• Distribute software more easily.Upgrade applets
  easily from a central server. Applets take
  advantage of the feature of allowing new classes
  to be loaded "on the fly," without recompiling
  the entire program.