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Advice to Quickly Learn Java and Keep Up

  Difficulties Learning Java

How to Improve

The 10 Most Common Java Mistakes

The 10 Developing Mistakes

Where to Find Info

What to Read

How to Troubleshoot

Difficulties Learning Java

To master Java you need to know:

- how to solve problems algorithmically using Java's syntax and environment

- the various classes contained in Java's packages and how to use them

- the OO model and the design behind Java's classes

How to Improve

Read other people's code

Experiment with the language itself

Experiment with all the basic classes

Read Java's source code

Write the same program from scratch each time trying a different way

Spend time reflecting on a design and try to identify parts that worked well, felt nice and looked beautiful

When you find yourself spending a significant amount of time designing over implementing it's time to start learning OOD methods and Design Patterns

The 10 Most Common Java Mistakes

Missing ( ) [ ]

Forgotten Imports

A Class for an Object

Spelling mistake

Wrong Signature

Return nothing = void

Wrong equality

Endless loops

Many public classes

Trusting your code without testing!
Unpredictable error messages

Class not Found

Method not found (if not static)

Various error messages

Wrong type of Arguments

Invalid method declaration

Incompatible type for if

Program seems to be hanged

Public class x must be defined in a file called ""


The 10 Developing Mistakes

Blob, The God class

Lava Flow

Functional Decomposition


Golden hammer

Spaghetti Code

Cut and Paste

Swiss Army Knife

Reinvent the wheel

Reach a dead end
Find related concepts and break it

Only prevention or else painful cure

similar to the Blob

Remove and trim often

Expand your horizons

Refactoring - Clean up

Try to reuse at the black box level


Find the right info

Know what you are using


Where to Find Info



Application Developer

Dr. Dobbs Journal

Communications of the ACM


What to Read

Java Books :

Thinking in Java, Prentice-Hall 1998, ISBN: 0-13-659723-8

Java in a Nutshell, O'Reilly, 1997, ISBN: 1-56592-262-X

A Little Java, A few patterns, MIT Press 1998, ISBN: 0-262-56115-8

Design Books :

Design Patterns, Addison Wesley, 1995 ISBN 0-201-63361-2

Patterns Languages of Program Design 1,2,3, Addison Wesley


How to Troubleshoot

Debug either using a debugger or print statements

Try to isolate and identify the error's source

Sometimes -not very often- it is not your fault and you bumped into a genuine Java bug

In this case, it is quite likely that other people have already found a workaround. Search the Usenet and specially :