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Conclusion
Java goes to great lengths to help you give newly-created objects a good start in life. Java's initialization mechanisms help you to ensure that objects you design begin their lives in a valid, predictable state. But these mechanisms do not force you to design objects in this way. In the end, if you want your programs to produce objects that always begin their lives in a proper state, you must use the initialization mechanisms correctly.

For advice on how to put the initialization mechanisms described in this article to use in your programs and designs, see this month's Design Techniques column, "Designing object initialization."

Resources

• For the source code listings that go with this article, see
  http://www.javaworld.com/jw-03-1998/initialization/initialization.zip
• "Initialization of Fields," a section in the Java Language Specification, describes instance variable initializers
  http://www.javasoft.com/docs/books/jls/html/8.doc.html#24510
• "Constructor Declarations," a section in the Java Language Specification, describes instance variable initializers
  http://www.javasoft.com/docs/books/jls/html/8.doc.html#41652
• "Creation of New Class Instances," a section in the Java Virtual Machine Specification, gives a terse, technical description of the process of object initialization in the JVM
  http://www.javasoft.com/docs/books/vmspec/html/Concepts.doc.html#19124

About the author
Bill Venners has been writing software professionally for 12 years. Based in Silicon Valley, he provides software consulting and training services under the name Artima Software Company. Over the years he has developed software for the consumer electronics, education, semiconductor, and life insurance industries. He has programmed in many languages on many platforms: assembly language on various microprocessors, C on Unix, C++ on Windows, Java on the Web. He is author of the book: Inside the Java Virtual Machine, published by McGraw-Hill. Reach Bill at bv@artima.com.

This article was first published under the name Object Initialization in Java in JavaWorld, a division of Web Publishing, Inc., February 1998.