Java Swings/Java Swing
Java Swing is a library/toolkit released by Oracle as a part of Java language which enables Java programmers to create GUI and rich client applications.
Success Stories 
There are numerous applications that are written with Java Swings and new one pop up every day. Here are some examples
NetBeans is a Integrated Development Environment (IDE) written completely using Java. It runs on all platforms. Initially it was Java only IDE, but now it supports many languages like C, C++, Python, PHP to name a few.
Swing is a part of Java Foundation classes (JFC). JFC consists of the following modules
Swing GUI Components 
Swings GUI components are those which are button's, labels, combobox, text field, rich text editors, lists etc. Many components have features like drag and drop, sorting, printing, to name a few.
Pluggable Look-and-Feel Support 
Look and feel module defines how the component looks and feels to the user. Java swings application has a separate look and feel effect. The programmers can change the look and feel of their application to Windows look and feel or GTK look and feel. There are many hundreds of look and feel available from various sources.
Accessibility API 
Not all humans are perfect. There is a good chance that disabled person can use our program, hence your program must be accessible to him / her. JFC Accessibility API enables you to create programs that are accessible by providing these people with screen readers, braille displays so that they can get information from the user interface.
Java 2D API 
Java 2D API provides rich set of graphics functions to draw various basic shapes, text and images in your application. Java 2D has API's to generate high quality output to send for printers etc.
English is not the only language on this planet. Many people don't know any other language than their mother tongue. Hence when a programmer writes an application he must consider to release it in as many languages as possible. Java i18n (there are 18 letter's between 'i' and 'n' in Internationalization) helps programmers to develop applications in various different languages, thus you can target global audience.