August 3, 1999

What Final Does in Java

When you declare a class as final, it can no longer be subclassed. Java has used this for security purposes with classes like String and Integer. It also allows the

Understanding Interfaces

An interface describes the public methods that a class should implement along with the calling conventions of those methods. An Interface says nothing about implementation of its methods. In essence,

What ‘abstract’ does

When you declare a class as abstract, it cannot be instantiated. Only subclasses of an abstract class can be instantiated if they are not abstract themselves. When you declare a

What ‘synchronized’ does to a method

When you synchronize a method of a class, as in: public synchronized int getAge(){ …} that method will acquire a monitor lock before execution. If the synchronized method is static,

What ‘static’ Does

When you declare a field variable of a class as static, that field variable is instantiated only once, no matter how many instances of the class are created. In other

SQL Redirection to a Text File

Question: How do I redirect the output of a SQL query to a file? Answer: Use the isql command-line switches to redirect the output of a query to a file.

Getting Data That Is in One of Two Tables

Question: I have a query that retrieves a field which is a foreign key in two tables. The tables are organization_name and person_name. Each instance of the foreign key is