Java

This page will be a collection of resources on Java programming.

Documentation

• Thinking in Java. This links to a mirror for the third edition.
• Official Sun documentation.

Differences from C++

• Inner classes: Although nested classes exist in C++, they are rarely used, and anyway it seems that the only effect of nested classes is on namespaces. Inner classes in Java have the interesting features that they can access their enclosing class object, and all of its members, directly.

• Inner local classes: Local classes defined inside a statement block (a function block for example) can even access the final local variables of the function. Nice!

• Anonymous inner classes: When you define the body of a class directly after a new keyword, you are defining an anonymous class. This class can derive from an existing class or implement an interface. The syntax is:

MyInterface my_instance = new MyInterface()
{
   // Here you write the body of the class
};

Note that with anonymous classes, you cannot have more than one object of the class. This limitation is not present with inner local classes, so the only point of an inner local class (vs. an anonymous class) is to create more than one instance of the class.

• Note that there is no such thing as anonymous or inner interfaces. What you do generally, however, is create a class that will implement an interface.