The programming language Java was introduced to the IT community as an "easy-to-learn" and "easy-to-use" language (typically referring to C++ for comparison). While this is certainly true, it turns out that even this supposedly easy language offers a lot of choices and comes with many programming idioms that must be understood thoroughly in order to produce high-quality software implemented in Java.

In this tutorial we look into the less obvious limitations of some concepts and discuss some fundamental, yet typical misunderstandings. We will focus on two language features that exist in Java since its advent: the implications of reference semantics on object copying and comparison and the use of exceptions for error indication and error handling.

Copying and Comparison. Regarding object copying and comparison in Java we examine the semantics of clone() and equals(). Questionable implementations of these functions can be found galore (in the JDK, in popular textbooks, even in commercial applications). It turns out that correct and symmetric implementation of these two functions is a non-trivial task. We will look into the details.
Exception Handling. Use of exceptions is mandatory in Java and cannot be avoided, yet in practice they are often misunderstood. We explain why and when one would want to handle exceptions at all (a common misunderstanding is that every potential exception must be caught.)

We discuss common problems such as exception hiding, improper use of throws specification, and resource leaks and inconsistent object state. '