Features of Java

• Simple, Small and familiar
• Compiled and interpreted
• Platform independent and portable
• Pure Object_Oriented
• Distributed
• Robust
• Secure
• High Performance
• Multithreaded and Interactive
• Dynamic and Extensible

 Platform Independent:

• The concept of Write-once-run-anywhere (known as the Platform independent) is one of the important key feature of java language that makes java as the most powerful language. Not even a single language is idle to this feature but java is more closer to this feature.
• The programs written on one platform can run on any platform provided the platform must have the JVM.

Simple, Small and Familier:

• There are various features that makes the java as a simple language. Programs are easy to write and debug because java does not use the pointers explicitly.
• It is much harder to write the java programs that can crash the system but we can not say about the other programming languages.
• Java provides the bug free system due to the strong memory management. It also has the automatic memory allocation and deallocation system.

Object Oriented:
      To be an Object Oriented language, any language must follow at least the four characteristics.
   Inheritance         
          It is the process of creating the new classes and using the behavior of the existing classes by   extending
          them  just to  reuse  the existing code and adding the additional features as needed. 
   Encapsulation         
          It is the mechanism of combining the information and providing the abstraction.
   Polymorphism          
          As the name suggest one name multiple form, Polymorphism is the way of providing the different       
          functionality by the  functions  having the same name based on the signatures of the methods.
     Dynamic binding  
          Sometimes we don't have the knowledge of objects about their specific types  while writing our code. It is    
          the way  of providing the maximum functionality to a program about the specific type at runtime. 

• As the languages like Objective C, C++ fulfills the above four characteristics yet they  are not fully object oriented languages because they are structured as well as object oriented languages.
• But in case of java,  it is a fully Object Oriented language because object is at the outer most level of data structure in java. No stand alone methods, constants, and variables are there in java. Everything in java is object even the primitive data types can also be converted into object by using the wrapper class.

Robust:

• Java has the strong memory allocation and automatic garbage collection mechanism. It provides the powerful exception handling and type checking mechanism as compare to other programming languages.
• Compiler checks the program whether there any error and interpreter checks any run time error and makes the system secure from crash. All of the above features makes the java language robust.

Distributed:

• The widely used protocols like HTTP and FTP are developed in java. Internet programmers can call functions on these protocols and can get access the files from any remote machine on the internet rather than writing codes on their local system.

Portable:

• The feature Write-once-run-anywhere  makes the java language portable provided that the system must have interpreter for the JVM.
• Java also have the standard data size irrespective of operating system or the processor. These features makes the java as a portable language.

Dynamic:

• While executing the java program the user can get the required files dynamically from a local drive or from a computer thousands of miles away from the user just by connecting with the Internet.

Secure:

• Java does not use memory pointers explicitly. All the programs in java are run under an area known as the sand box. Security manager determines the accessibility options of a class like reading and writing a file to the local disk.         
• Java uses the public key encryption system to allow the java applications to transmit over the internet in the secure encrypted form. The bytecode Verifier checks the classes after loading.

Performance:

• Java uses native code usage, and lightweight process called  threads. In the beginning interpretation of bytecode resulted the performance slow but the advance version of JVM uses the adaptive and just in time compilation technique that improves the performance.

Multithreaded:

• As we all know several features of Java like Secure, Robust, Portable, dynamic etc; you will be more delighted to know another feature of Java which is Multithreaded.
• Java is also a Multithreaded programming language. Multithreading means a single program having different threads executing independently at the same time.
• Multiple threads execute instructions according to the program code in a process or a program. Multithreading works the similar way as multiple processes run on one computer.  
• Multithreading programming is a very interesting concept in Java. In multithreaded programs not even a single thread disturbs the execution of other thread.
• Threads are obtained from the pool of available ready to run threads and they run on the system CPUs. This is how Multithreading works in Java which you will soon come to know in details in later chapters.

Interpreted:

• We all know that Java is an interpreted language as well. With an interpreted language such as Java, programs run directly from the source code. 
• The interpreter program reads the source code and translates it on the fly into computations. Thus, Java as an interpreted language depends on an interpreter program.
• The versatility of being platform independent makes Java to outshine from other languages. The source code to be written and distributed is platform independent. 
• Another advantage of Java as an interpreted language is its error debugging quality. Due to this any error occurring in the program gets traced. This is how it is different to work with Java.