Author Archives | Christy

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Knowing about your Database

October 26, 2007

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We use the Jdbc APIs for accessing the data from the database system. However, the different databases from different vendors will vary a lot in their underlying model and functionalities. For example, a feature supported in one database might not be supported in another database. So, even before working with a database, it is important [...]

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Customizing Dragging and Dropping for Swing Components

October 26, 2007

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Swing’s Drop and Drop API can be used for customizing Drag and Drop support. For most of the commonly used components like Text Components, Color Chooser, File Chooser etc, the dropping support is enabled by default. We have to explicitly enable the dragging support by calling the setDragEnabled() method. Before getting into customizing them, let [...]

Locking Files using Java

October 26, 2007

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File Locking can be achieved in java by making use of the New I/O API (nio). Before the advent of New I/O API, there was no direct support in Java for locking a file. It is important to understand that File locking is hugely dependent on the native operating system on which the program is [...]

Precise rounding of decimals using Rounding Mode Enumeration

October 9, 2007

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The Rounding Mode Enum in java.math package is used to perform precise rounding of decimal values. It was introduced in Java 5.0. This Enum provides various constants each of which is used for different modes of rounding. The decimal value would be rounded off to the number of decimal places based on the scale that [...]

Using the Prototype pattern to clone objects

October 9, 2007

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Prototype pattern is one of the creational patterns that concentrate on duplicating objects if needed. Assuming that we are in process of creating a template. Most of the times, we copy an existing template, do some changes in it and then will use it. Technically, we make a copy of the source, make some changes [...]

How to send mail using Java Mail API?

October 9, 2007

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The Java Mail API provides support for sending and receiving electronic mail messages. The API provides a plug-in architecture where vendor’s implementation for their own proprietary protocols can be dynamically discovered and used at the run time. Sun provides a reference implementation and its supports the following protocols namely, Internet Mail Access Protocol (IMAP) Simple [...]

Passing arguments and properties from command line

October 9, 2007

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Arguments and properties can be passed to a java application from command line. In this techical tip, let us see how to pass arguments as well as properties from command line. Passing arguments from command line The syntax to pass arguments from command line is as follows, 1 2   java <classname> <argument1> <argument2> <argument3> [...]

Generation of Random Numbers

October 9, 2007

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Random numbers in java can be generated either by using the Random class in java.util package or by using the random() method in the Math class in java.lang package. In both these approaches, we only get a pseudo random number and not a true random number because it is all generated based on some mathematical [...]

Downloading Content from the Internet

October 9, 2007

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Let us write a Simple Downloader in this techincal tip by making use of the classes with java.net package. URL stands for Uniform Resource Locator and it is used to locate a resource in the Web in a standard fashion. A resource in the Web can be anything; it can be as simple as Html [...]

Creating user defined exceptions

October 9, 2007

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Though Java provides an extensive set of in-built exceptions, there are cases in which we may need to define our own exceptions in order to handle the various application specific errors that we might encounter. While defining an user defined exception, we need to take care of the following aspects: The user defined exception class [...]