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:
Features of Java
There is given many features of java. They are also known as
java buzzwords. The Java Features given below are simple and easy to
understand.
- Simple
- Object-Oriented
- Portable
- Platform
independent
- Secured
- Robust
- Architecture
neutral
- Dynamic
- Interpreted
- High
Performance
- Multithreaded
- Distributed
Simple
According to Sun, Java language is simple because:
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syntax is based on C++
(so easier for programmers to learn it after C++).
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removed many confusing
and/or rarely-used features e.g., explicit pointers, operator overloading
etc.
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No need to remove
unreferenced objects because there is Automatic Garbage Collection in java.
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Object-oriented
Object-oriented means we organize our software as a
combination of different types of objects that incorporates both data and
behaviour.
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Object-oriented programming(OOPs) is a methodology that
simplify software development and maintenance by providing some rules.
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Basic concepts of OOPs are:
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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 software-based platform.
- 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 disk.
These security 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. All these points makes java robust.
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++)
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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.
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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.
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