Java History:

-Major features were derived from C (its syntax)and C++(its OOP principles).
-In C++, the object model implementation is not effective and it is very difficult to achieve platform-independence.
JAVA:

So, They thought that we need a language which gives better implementation to OOP principles(to manage the complexity of project) and as well need a language which can be used to write software applications for electronic devices like Micro oven ,Remote controls,Washing machines..etc.,
  • For that reasons, James Gosling along with his teammates(Green Team,in SunMicroSystems) started a project,called Green project in 1991 to develop a language which satisfies the platform-independence and gives the better refinement for OOP principles.
  • So, that Green project outcome was the language "Oak" in 1992.
  • Later on in 1995 they renamed Oak to JAVA(its an Island name).
Q) What do you mean by the platform-independence?
Ans: Platform independence means that we can write and compile the java code in one platform (eg Windows) and can execute that ".class" in any other supported platform eg (Linux,Solaris,etc).

How java changed internet?

-Generally, by using java we can write 2 kinds of programs:

                                          1.Applications(which can be executed by your OS)
                                          2.Applets(which are designed to be transmitted over internet and executed                                                               by the java compatible web browsers)
-Applets changed the entire web programming.
-Applets are self executable programs(active agents).

Issues:
        
  • Security(While you are downloading a content from internet,there may be a chance to attack viruses.But if that application was developed in java,no virus attacks are allowed into your system.)[JVM will take care about those kind of attacks].
  • Portability(The systems with different OSs,different CPUs,different internal resources can access and run an application(developed in java) through internet).


Q) What is JVM?
Ans: It is JAVA VIRTUAL MACHINE, which provides the runtime environment to our java applications.
Q) What was the first web browser developed in java?
Ans: WebRunner(Hot Java) by SunMicroSystems only.
Q) Which company developed Java?
Ans: SunMicroSystems (recently acquired by Oracle)

Java Buzzwords:

  1. Simple
  2. OOP
  3. Secure
  4. Portable
  5. Robust
  6. Multithreaded
  7. Architecture-neutral 
  8. High performance and Interpreted
  9. Distributed
  10. Dynamic
Simple: Easy to learn to C/C++ programmers(as well for novice users too).
OOP: Java is pure OOP language.[Even though it is having primitive types we can represent them as objects through Wrapper classes]
Secure and portable [Discussed above]
Robust:
No of concepts available in java which makes java as a robust language.Apart from them 2 main concepts are:
                 a)Memory management:(the unused objects will be automatically deallocated by Garbage                      Collector,where as in C/C++ manually you have to deallocate)
                 b)Exception handling:(Runtime errors can easily handle with java.Ex: Divided by zero                           error)
Multithreaded:(We can write a program that can do more than one task simultaneously)
Architecture-neutral:(Java applications goal was WORA[Write once,run any where,any                                                          time,forever] means that irrespective of CPU architecture we can run a                                                  compiled java code on any system)
High performance and Interpreted:
To execute java applications we use interpreter(JVM).Generally interpreters slowly translates the code when compare with compilers, But in our JVM internally we have a compiler, called JIT(Just-In-Time) to boost the performance.So, we can say that JVM executes the code little bit faster than  other languages interpreters.
Note: The code that is assigned to JIT is called as a "hot spot".
Distributed:
We can write applications which can be at different locations that they can communicate with each other to accomplish a common goal.
Dynamic:
We can embed some extra code with the bytecode dynamically without having any security issues during execution.


Next topic
 Data types(will be updated soon)













Comments

Post a Comment

Popular posts from this blog

Type Conversion and Casting

Q)   Which one is valid in the following?        int a=3.14;// INVALID      double d=35;//VALID Tell me the reason, Ans : As per the behavior of java data types I am listing out the order(numeric/integral) : (smaller to larger)                           byte                           short                           int                           long                          float                         double (So, we can not assign larger type value to a smaller type variable.) In java, we have two kinds of conversions:   1....
Read more

Data types:

Image
Java Is a Strongly Typed Language.   because of the following reasons, – First, every variable has a type, every expression has a type, and every type is strictly defined . – Second, all assignments, whether explicit or via parameter passing in method calls, are checked for type compatibility . • There are no automatic coercions or conversions of conflicting types as in some languages. • The compiler  checks all expressions and parameters to ensure that the types are compatible. Q) Any, type related errors will be detected by   whom? Ans :  Compiler The Primitive Types (Simple types) • Java defines eight primitive types of data:   byte, short, int , long    float, double   char &   boolean Integers This group includes byte, short, int , and long, which are for whole-valued signed numbers . Floating-point numbers This group includes float and double, which represent numbers...
Read more
Command-line arguments: -These are the values we pass to main() from the command line. Note: Observe the parameter type of main()--->Its a String type array. Example: Q) class Check{ public static void main(String[] ar){ System.out.println(ar[0]); System.out.println(ar[1]);  } } File name: Check.java Compilation: >javac Check.java Execution: >java Check hello hi hello hi ......................................................... Q) class Check1{ public static void main(String[] ar){ System.out.println(ar[0]+ar[1]);  } } File name: Check1.java Compilation: > javac Check1.java Execution: > java Check1 10 20 1020 ........................................................ Q) class Check2{ public static void main(String[] ar){ int x=Integer.parseInt(ar[0]);//parseInt() converts 'String' value to its corresponding 'int' type value int y=Integer.parseInt(ar[1]); System.out.println(x+y);  } } File name: Check2.java Compilation...
Read more