BioJava aims to provide a comprehensive set of Java components for the rapid development of applications in Bioinformatics. It contains interfaces for representing Sequences, Features, and other important bioinformatics concepts. It can also read and write sequence data in a variety of common formats and communicate with Ensembl databases and with DAS and BioCorba servers.
Jmol is a Free, Open Source molecule viewer and editor. It is a collaboratively developed visualization and measurement tool for chemical scientists. Jmol is an active project, and there are new features being added to it on a daily basis. Users are encouraged to modify it to fit their needs and to contribute their changes to the project.
The Chemistry Development Kit (CDK) is a library of Java classes for chemo-, bioinformatics, computational chemistry, and chemometrics. It provides important algorithms like substructure search, SMILES, Gasteiger charges, QSAR descriptor calculation, 3D structure generation, 2D layout and rendering, many IO formats, atom typing, and more.
Taverna is a collection of workflow enactment and description components, including a high level language for workflows called Scufl (Simple Conceptual Unified Flow Language), a pure Java object model, parser to populate the model, and a set of views and controllers (including some Swing components to drop into your workflow-enabled applications). In order to actually run workflows you also need the myGrid workflow enactment engine.
The Biochemical ALgorithms Library (BALL) is a framework for rapid application development in molecular modeling and structural bioinformatics. BALL provides an extensive set of data structures as well as classes for molecular mechanics, advanced solvation methods, comparison and analysis of protein structures, file import/export, NMR shift prediction, and visualization. Its extensibility results from an object-oriented and generic programming approach.