- 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 software-based platform.
The Java platform differs from most other platforms in the sense that
it's a software-based platform that runs on top of other hardware-based
platforms.It has two components:
- Runtime Environment
- API(Application Programming Interface)
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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).
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Secured
Java is secured because: |
- No explicit pointer
- Programs run inside virtual machine sandbox.
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- 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.
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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.
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Architecture-neutral
There is no implementation dependent features e.g. size of primitive types is set.
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Portable
We may carry the java bytecode to any platform.
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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
shares the same memory. Threads are important for multi-media, Web
applications etc.
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