Showing posts with label internals of java. Show all posts
Showing posts with label internals of java. Show all posts

Sunday, February 26, 2017

Features of Java

Hello Readers, Once again welcome back to Java Jagran. Today I am going to discuss features of java. There is given many features of java. They are also known as java buzzwords. Here I am listing some important features of java.
  • Simple
  • Object-Oriented
  • Platform independent
  • Secured
  • Robust
  • Architecture neutral
  • Portable
  • Dynamic
  • Interpreted
  • High Performance
  • Multithreaded
  • Distributed
Now let's discuss each feature in detail.

Simple:

  • The syntax is based on C++ (so easier for programmers to learn it after C++).
  • Removed much confusing and/or rarely-used features e.g., explicit pointers, operator overloading etc.
  • No need to remove referenced objects because there is Automatic Garbage Collection in java.

Object-oriented

  • Object-oriented means we organise our software as a combination of different types of objects that incorporate both data and behaviour.
  • Object-oriented programming(OOPs) is a methodology that simplifies software development and maintenance by providing some rules.
  • Basic concepts of OOPs: Object,Class,Inheritance,Polymorphism,Abstraction,Encapsulation

Platform Independent

  • A platform is the hardware or software environment in which a program runs.
  • There are two types of platforms software-based and hardware-based. Java provides a software-based platform.The Java platform differs from most other platforms in the sense that it is a software-based platform that runs on the top of other hardware-based platforms.
  • It has two components:
    • Runtime Environment
    • API(Application Programming Interface)
  • Java code can be run on multiple platforms e.g. Windows, Linux, Sun Solaris, Mac/OS etc. Java code is compiled by the compiler and converted into bytecode. This bytecode is a platform-independent code because it can be run on multiple platforms i.e. Write Once and Run Anywhere(WORA).

Secured

  • Java is secured because: 
    • No explicit pointer: Java Programs run inside virtual machine sandbox
    • Classloader: Adds security by separating the package for the classes of the local file system from those that are imported from network sources.
    • Bytecode Verifier: Checks the code fragments for illegal code that can violate access right to objects.
    • Security Manager: determines what resources a class can access such as reading and writing to the local disksecurities
  • These are provided by java language. Some security can also be provided by application developer through SSL, JAAS, Cryptography etc.

Robust

  • Robust simply means strong. Java uses strong memory management. There are lack of pointers that avoids security problem. There is automatic garbage collection in java.
  • There is exception handling and type checking mechanism in java.

Architecture-neutral

  • There is no implementation dependent features e.g. size of primitive types is fixed.
  • In C programming, int data type occupies 2 bytes of memory for 32-bit architecture and 4 bytes of memory for 64-bit architecture. But in java, it occupies 4 bytes of memory for both 32 and 64 bit architectures.

Portable

  • We may carry the java bytecode to any platform.

High-performance

  • Java is faster than traditional interpretation since byte code is “close” to native code still somewhat slower than a compiled language (e.g., C++)

Distributed

  • We can create distributed applications in java. RMI and EJB are used for creating distributed applications. We may access files by calling the methods from any machine on the internet.

Multi-threaded

  • A thread is like a separate program, executing concurrently. We can write Java programs that deal with many tasks at once by defining multiple threads. The main advantage of multi-threading is that it doesn’t occupy memory for each thread. It shares a common memory area. Threads are important for multi-media, Web applications etc.

Saturday, May 21, 2016

Enhance for loop in Java part-1


Friends today i am going to explain about enhance for loop/ for each loop. As a name it is a next to for loop. In for loop we user to iterate an array or object based on index or some condition. But in case of enhance for loop we need not to do that( or we can say that we can't do that). Enhance for loop internally uses these index or condition to iterate the array/ object.

Basically there is no concept like enhance for loop in Java for JVM. Actually this enhance for loop is only for the compiler. Compiler only understands enhance for loop and convert it into simple for loop before generation byte code. So if you see the byte code then you haven't find any enhance for loop there. For example:  If we are writing a java code fro iterating an array using enhance for loop then that is look like this:





But When we will decompile this class file then we will get like this:




So friends, this how enhance for loop works. We all know that we can use object also in enhance for loop. In next post i will write about how enhance for loop works with objects. For watching full enhance for loop video on you-tube Click here