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"The Java Language
Environment: A White Paper" by James
Gosling and Henry McGilton lists
a number of buzzwords as the requirements for Java. They show a
table comparing Java with Smalltalk, TCL, Perl, Shells, C and C++
using the following criteria:
Naturally, Java comes off looking
good!
Here's what they meant:
- Easy programming
- Without a lot of esoteric training
- Familiar -- like C++
- Small:
- Base interpreter and class support
- Base standard libraries and thread
support
- Focuses design on data (objects)
and on interfaces to them.
- Java's O-O support is essentially similar
to that of C++, but simplified.
- Unlike C++, Java is pure O-O,
not hybrid.
- Extensive class library for Internet
support:
- Greatly simplifies Internet programming!
- Intended for writing reliable programs.
- Early checking for possible problems.
- More strongly typed than C/C++.
- Exceptions are used a lot, and enforced.
- Essential for networked/distributed
environments.
- Designed to prevent viruses and other
outside tampering.
- Java compiler produces bytecodes
- Java virtual machine (JVM)
executes these bytecodes wherever it runs.
- Development process can be much
faster.
- Performance tends to suffer, compared with
compiled code.
- Just-in-time (JIT) compilers
improve performance considerably.
- Designed to adapt to an evolving
environment.
- Can add code to a running program!
- Provides run-time type information.
- JDK 1.1 adds powerful reflection
capabilities.
- Primitive data types have the same
size and representation on all systems
- Strings are stored in a standard Unicode
format (internationalization)
- Classes for windows, network access, etc.,
work across platforms.
- Original AWT classes produced mediocre
look and feel across platforms.
- JDK 1.1 provides AWT enhancements and
additional class libraries which should improve matters
greatly.
- Java compiler produces bytecodes, which
are not machine-specific
- Bytecode instruction set works well with
today's machines.
- Java machines have been built which
execute the Java bytecode instruction set as native code.
- Ability to "do more than one
thing at a time".
- Can produce better responsiveness and
real-time behavior.
- Thread support built into the language.
- Some JVM implementations better than
others in terms of multithreading.
- Much better error handling than
conventional approaches.
- Forces the programmer to deal with
potential errors and/or abnormal conditions.
- Exceptions are part of the
interface to an object.
- Some current Java implementations are not
high performance.
- Some are better than others (JIT compilers
can make a big difference)
- Situation will improve over time, with
competition -- it's already happening.
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