Introduction
Vector/Enumeration
Hashtable,HashMap
   Properties
Collections
Iterator/ArrayList
Generics
Preferences API
  Demo 1
Concurrency Utils
Enumerated Type
Arrays Class
String Tools
  String
  StringBuffer
  StringBuilder
  StringTokenizer
  String.split()
Calendar,Date,Time
  Demo 2
  Demo 3
Other Utilities
Exercises

In general, the performance of Java programs relative to programs in other languages carrying out the same tasks has improved considerably since Java first appeared. The early JVMs did straight-forward interpretation of the Java bytecode. This put the Java programs at a disadvantage compared to programs that had been compiled from, say, C/C++ into local machine code. Subsequently, however, the JVMs became much more sophisticated and used techniques such as Just-in-Time compilation and adaptive techniques to convert bytecode on the fly into local machine code. This provides performance similar to that of compiled language programs in many cases, especially where particular sections of code, e.g. loops, are executed repeatedly.

See the sections in Chapter 1 where we discussed the JVM:

• Chapter 1: Java Virtual Machine
• Chapter 1: Supplement: Advanced JVMs

Chapter 1: Tech: Shortcomings discusses problems with the language that limit performance on some kinds of mathematical operations such as those with large arrays.

We provide here a list of links to Java benchmarks and performance studies with them.

See the following pages for discussions and demos of Java performance:

• Chapter 12: Java : Timing & Performance - discussion of Java performance enhancements and a demo illustrating how timing measurements can be made.
• Chapter 24: Java Processor Performance - comparing hardware implementations of Java bytecode processing.

If Java cannot perform a mathematical task to the speed required but the Java GUI and networking capabilities are still desired, it is possible to connect a Java program to a C/C++ computation engine using the Java Native Interface (JNI) techniques discussed in Chapter 22.

Most recent update: Oct. 18, 2005

              Tech
ArbitaryPrecision
   BigInteger
   BigDecimal
Bit Handling
Exercises

           Physics
Data Gen&Analysis
  Demo 1
  Demo 2
Exercises