Dr.Nikolai Bezroukov's Devil's Advocate Commentary on "Thinking in Java" by Bruce Eckel.
Chapter 2

Chapter 2 Everything is Object

The chapter is devoted to explanation of data types in Java and contains the following subsections:

• You manipulate objects with handles
• You must create all the objects (Where storage lives; Special case: primitive types; Arrays in Java)
• You never need to destroy an object (Scooping; Scope of objects)
• Creating new data types: class
• Methods, arguments and return values
• Building a Java program (contains Name visibility; Using other components The static keyword)
• Your first Java program

• Comments and embedded documentation (Comment documentation; Syntax; Embedded HTML; @see: referring to other classes; Class documentation tags; Variable documentation tags; Method documentation tags; Documentation example;
• Coding style

• Summary & Exercises

Logically we have two groups of topics: one group is connected with storage allocation, typing and visibility aspects in Java. The second is about programming style and imbedded documentation.

The key questions that should be answered in this chapter are storage allocation and visibility.  Although the author explain basic data types in Java very clearly, the questions of storage allocation and visibility should be explained in more detail.

There essentially three kinds of storage:

• static, when the space for variable or structure is allocated by the program loader. All code (machine instruction) are usually located in static storage.   Constant are usually allocated in the static storage. Early versions of Fortran used static storage as the main allocation method. That's why Fortran programs usually beat Algol60 in numerical computations. 

• procedure stack - when storage for variable is allocated at procedure entry and is discarded at the procedure exit

• heap-based - when storage for variable is allocated at some memory area that is managed separately from the program and at least theoretically can outlive execution of the program. the keyword new in Java is actually a call to the heap storage allocator like malloc in C

In C variables, arrays and structures can be static, automatic or heap-based. In Java the objects are always allocated on from the heap and keyword static is very misleading -- it's not about static storage it's about the number of allocations on heap. If member of a class is declared static, it means that that data allocated ones and the same memory is accessible from any instance of the class.

It's unclear from the text of the book how Java allocates simple (non object) variable -- in procedure stack or not.

The very important advantage of keeping as much as possible in heap is that exception handing and multithreading became much more simplified.  One should understand that in deeply nested exception, execution of catch statement can involve correct exit from all called procedures in the procedure stack. 

Java object variables are much like object pointers in C/C++.

Chapter 2 contain among other things a good overview of visibility (page 80) and static attribute. Static attribute in Java is not the same static as in Fortran, PL/1, C and other traditional languages. The memory is allocated from the heap on the first new operation -– the first instance of the object. As such it is subject to garbage collection. But at the same time all other instances use this already allocated storage. So it is kinf of common storage area for all instances of the class and in this sense probably can be better called common.

Java programming style

Chapter 2 also explain the elements of  programming style and creation of embedded documentation. Introduction to Javadoc is good and well placed, but coding style section is very superficial.

The main complain about Javadoc section is absence of references to literate programming movement.   Javadoc is a simplistic implementation of the idea of literate programming by D.Knuth. So the idea is more than 10 years old and looks somewhat archaic. Probably much better ( but more radical) and effective implementation of the same idea would be to use HTML as the standard representation of Java programs. Here Java designers were (unfortunately) very conservative and decided to stick to ASCII :-(.   I provided some information about literate programming movement (which was most popular in 1989-1994) in the link section of the Commentary.  Hope it would be useful. BTW the simplest platform for literary programming now seems to be MS Word 97 or other word processor with a powerful scripting language and ability to generate both HTML and plain text.

As for coding style I object to using a single operator after if, while, for, etc. IMHO there should always be a curvy braces, so that modification of the program became easier. 

Programs are somewhat easier to maintain if they have a consistent style, but its important not to go to far. Religious zeal here is definitely harmful, but a good pretty printer would be definitely beneficial.  As TIJ does not provide style guidelines for Java I will provide my own borrowed mainly from Programming in Java Style Guide

• Place each class in a separate file. Files must have the same name as the class. Jbuilder and Semantic Cafe provide a starting template for each new class. Use them, if possible. 

• In packages follow Sun's recommendations. Package per project or reusable group.

• In methods it make sense to place constructors at the start, methods are better alphabetically placed after each other.

• Comments are often said to be either strategic or tactical. A strategic comment describes what a function
  or section of code is intended to do, and is placed before this code. A tactical comment describes what a single line of code is intended to do, and is placed, if
  possible, at the end of this line. Unfortunately, too many tactical comments can make code unreadable. For this reason, it is recommended to primarily use
  strategic comments, unless trying to explain very complicated code. If the characters // are consistently used for writing comments, then the combination /* */ may be used to make comments out of entire sections of code during the development and debugging phases." Java does not allow nesting of /* */.

• Names:

  • Classes -- NamedLikeThis

  • Exception Class  -- NamedWithException;

  • Interface Class end with the letters 'able' as in the class -- Observable

  • Method  -- namedLikeThis (if returns boolean boolean -- isAttributeName(),  if   get/set  an attribute getAttributeName(),   void setAttributeName(Type attribute;

  • Constants (final static) UPPERCASE_WITH_UNDERSCORE_IF_NEEDED

  • Local variables  -- someName

• Preferred order of access modifiers -- static abstract synchronized volatile final native

• Indentation. Consistent indentation should be provided with prettyprinter. In the absence of built-in prettyprinters in JDM, Jbuilder and Semantic Cafe existing C or, better,  Perl prettyprinters can be used (see links below).  General recommendations for prettyprinting Java can be limited to the following:

  • Consistent number of spaces in the indentation unit. Minimum is two spaces, max is probably eight. Use of tabs is not recommended.

  • Block statement (compound) -- braces should on separate lines if it contain more than one statement.

  • Flow Control Statements -- always use braces even if an empty block or only one line.  Left-brace ("{") at end of line. Right-brace ("}") on a separate line.
    
    // Example of recommended use of braces
    if (a > b) {
       max_indent=a;
       min_indent=b;
    }
    else {
       max_indent=b;
       min_indent=a;
    }
    

• Matching open/close braces is often a mess in Java. that can be considered as a language disign oversight -- end brace markers are known since sixties (in PL/1 they also close all unclosed braces). To compencate for that one can add comments with keyword prefixed by "--" to make brace nesting more clear
  for(;;) {
    statement(s);
  } //--for

Useful links

Programming in Java Style Guide  -- this is short and nononcence guide that should be read and following. the content partially reproducred above

• Gary's bookmarksJavastyle

• Java Style Guide (Nasa)

• Draft Java Coding Standard -- written by Doug Lea and released to the public domain.

• Draft Java Coding Standard - Doug Lee/NASA
• Java Coding Standards - AmbySoft Inc.
• Java Style Guide - U.S. Navy
• Java Style Guidelines
• Mark Fussell's Java Development Standards

• AmbySoft Inc. Java Coding Standards

• The Coding Standards Repository

• AmbySoft Inc. Java Coding Standards

• Kent Sandvik's Java Coding Style Guidelines

• Taligent's Java Cookbook

• Naval Postgraduate School Java Style Guide

• Solo Software Engineering home page

Prettyprinters

• Pretzel Homepage
  Pretzel is a program that generates a prettyprinter module from a formal description of the way a certain language should be prettyprinted. A
  prettyprinter is a function or program that rearranges source code to enhance its readability. Prettyprinters generated by pretzel output LaTeX
  source code that can be used within your own documents. NB that pretzel produces modules, not programs! It also includes features to make
  Pretzel prettyprinters suitable for any target typesetter you like, they may even produce HTML output.

• pb -- Perl Beautifier -- This script processes Perl scripts, cleans up and indents, like cb does for C

Literate programming movement

It's interesting to note than like famous Moliere's character Bruce Eckel practiced kind of literary programming in writing TIJ without knowing how it is called :-).

• Yahoo!Literate Programming -- do not expect much. The idea is almost forgotten.

• LitProg Philosophy

• FAQ - comp.programming.literate -- old, never updated since 1995

• Literate Programming Library -- very old, a lot links are broken

• Knuth Donald personal WEB page -- some references to CWEB

• Donald Knuth CLB Interview 12/07/93

Etc

Society

Groupthink : Two Party System as Polyarchy : Corruption of Regulators : Bureaucracies : Understanding Micromanagers and Control Freaks : Toxic Managers :   Harvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Neoliberalism  : The Iron Law of Oligarchy : Libertarian Philosophy

Quotes

War and Peace : Skeptical Finance : John Kenneth Galbraith :Talleyrand : Oscar Wilde : Otto Von Bismarck : Keynes : George Carlin : Skeptics : Propaganda  : SE quotes : Language Design and Programming Quotes : Random IT-related quotes :  Somerset Maugham : Marcus Aurelius : Kurt Vonnegut : Eric Hoffer : Winston Churchill : Napoleon Bonaparte : Ambrose Bierce :  Bernard Shaw : Mark Twain Quotes

Bulletin:

Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient markets hypothesis : Political Skeptic Bulletin, 2013 : Unemployment Bulletin, 2010 :  Vol 23, No.10 (October, 2011) An observation about corporate security departments : Slightly Skeptical Euromaydan Chronicles, June 2014 : Greenspan legacy bulletin, 2008 : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Financial Humor Bulletin, 2010 : Inequality Bulletin, 2009 : Financial Humor Bulletin, 2008 : Copyleft Problems Bulletin, 2004 : Financial Humor Bulletin, 2011 : Energy Bulletin, 2010 : Malware Protection Bulletin, 2010 : Vol 26, No.1 (January, 2013) Object-Oriented Cult : Political Skeptic Bulletin, 2011 : Vol 23, No.11 (November, 2011) Softpanorama classification of sysadmin horror stories : Vol 25, No.05 (May, 2013) Corporate bullshit as a communication method  : Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law

History:

Fifty glorious years (1950-2000): the triumph of the US computer engineering : Donald Knuth : TAoCP and its Influence of Computer Science : Richard Stallman : Linus Torvalds  : Larry Wall  : John K. Ousterhout : CTSS : Multix OS Unix History : Unix shell history : VI editor : History of pipes concept : Solaris : MS DOS :  Programming Languages History : PL/1 : Simula 67 : C : History of GCC development :  Scripting Languages : Perl history   : OS History : Mail : DNS : SSH : CPU Instruction Sets : SPARC systems 1987-2006 : Norton Commander : Norton Utilities : Norton Ghost : Frontpage history : Malware Defense History : GNU Screen : OSS early history

Classic books:

The Peter Principle : Parkinson Law : 1984 : The Mythical Man-Month :  How to Solve It by George Polya : The Art of Computer Programming : The Elements of Programming Style : The Unix Hater�s Handbook : The Jargon file : The True Believer : Programming Pearls : The Good Soldier Svejk : The Power Elite

Most popular humor pages:

Manifest of the Softpanorama IT Slacker Society : Ten Commandments of the IT Slackers Society : Computer Humor Collection : BSD Logo Story : The Cuckoo's Egg : IT Slang : C++ Humor : ARE YOU A BBS ADDICT? : The Perl Purity Test : Object oriented programmers of all nations : Financial Humor : Financial Humor Bulletin, 2008 : Financial Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related Humor : Programming Language Humor : Goldman Sachs related humor : Greenspan humor : C Humor : Scripting Humor : Real Programmers Humor : Web Humor : GPL-related Humor : OFM Humor : Politically Incorrect Humor : IDS Humor : "Linux Sucks" Humor : Russian Musical Humor : Best Russian Programmer Humor : Microsoft plans to buy Catholic Church : Richard Stallman Related Humor : Admin Humor : Perl-related Humor : Linus Torvalds Related humor : PseudoScience Related Humor : Networking Humor : Shell Humor : Financial Humor Bulletin, 2011 : Financial Humor Bulletin, 2012 : Financial Humor Bulletin, 2013 : Java Humor : Software Engineering Humor : Sun Solaris Related Humor : Education Humor : IBM Humor : Assembler-related Humor : VIM Humor : Computer Viruses Humor : Bright tomorrow is rescheduled to a day after tomorrow : Classic Computer Humor

The Last but not Least Technology is dominated by two types of people: those who understand what they do not manage and those who manage what they do not understand ~Archibald Putt. Ph.D

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Last modified: March 12, 2019