Java provides all he luxuries of object-oriented programming:class

hierarchy,inheritance,encapsulation,and polymorphism--in a context that is truly useful and

efficient.
The main reason for developing object-oriented software,besides clarity and simplicity,is

the desperate hope that somehow the objects you develop will be reused.Java not only

encourages software reused.Java not only encourages software reuse,it demands it.To write

any sort of Java program,no matter how simple,you must build on the classes and methods of

the Java API.
Once you have begun developing software in Java,you have two choices:
¡ñ Build on the classes you have developed,thereby reusing them.
¡ñ Rewrite your software from scratch,copying and tailoring useful parts of existing

software.
With Java,the temptation to start from scratch is no longer appealing.Java's object-oriented

structure forces you to decelop more useful,more tailorable, and much simpler software the

first time around.
3.Java Is Safer and More Reliable
Java is safer to use than C++ because it keeps you from doing the things that you do

badly,while making it easier to do the things that you do well.
Java won't automatically convert data types.You have to explicitly convert from one class

another.C++,under the most undesirable conditions,will automatically convert one type to

another.It has all the flexibility of assembly code.Java doesn''t assume that you know what

you are doing.It makes sure that you do.
C++ pointers don'exist in Java.You can no longer access objects indirectly or by chance.You

don't need to.You declare objects and reference those objects directly.Complex pointer

arithmetic is avoided.If you need an indexed set of objects,you can use an array of

objects.The concept of "the address of an object" is eliminated from the programming errors

that go another assembly language dinosaur is laid to rest.As a result,it becomes much

easier to do things correctly on Java. www.xuexi86.com
Java's reliability extends beyond the language level to the compiler and the runtime

system.Compile-time checks identify many programming errors that go undetected in other

progamming languages.These checks go beyond syntactic checking to ensure that statements are

semantically correct.
Runtime checks are also more extendsive and effective.Remember your teacher or mom telling

you to "Check your work twice to make sure it's right?"The Java linker understands class

types and performs compiler-level type checking,adding redundancy to reliability.It also

performs bounds checking and eliminates indirect object access,even under error conditions.

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