Eclipse Java development tools (JDT) Overview

The JDT project contributes a set of plug-ins that add the capabilities of a full-featured Java IDE to the Eclipse platform. The JDT plugins provide APIs so that they can themselves be further extended by other tool builders.
The JDT plugins are categorized into:

JDT APT

JDT APT adds annotation processing support to Java 5 projects in Eclipse. It provides the following features:

• Support for running annotation processors written for Sun’s command-line apt tool
• Contribution of annotation-based build artifacts during incremental build
• Contribution of problem markers for annotation-based problems

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JDT Core

JDT Core defines the non-UI infrastructure. It includes:

• An incremental Java builder
• A Java Model that provides API for navigating the Java element tree. The Java element tree defines a Java centric view of a project. It surfaces elements like package fragments, compilation units, binary classes, types, methods, fields.
• Code assist and code select support
• An indexed based search infrastructure that is used for searching, code assist, type hierarchy computation, and refactoring.
• Evaluation support

The JDT Core infrastructure has no built-in JDK version dependencies.

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JDT Debug

JDT Debug implements Java debugging support and works with any JDPA-compliant target Java VM. It is implemented on top of the language independent "debug model" provided by the platform debugger.

JDT debug provides the following debugging features:

• Launching of a Java VM in either run or debug mode
• Attaching to a running Java VM
• Expression evaluation in the context of a stack frame
• Scrapbook pages for interactive Java code snippet evaluation
• Dynamic class reloading where supported by Java virtual machine

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JDT Text

JDT Text provides the Java editor with the following features:

• Keyword and syntax coloring
• Context specific (Java, Javadoc) code assist and code select
• Method level edit
• Margin annotations for problems, break points, or search matches
• Outliner updating as editing takes place
• API help shows Javadoc specification for selected Java element in a pop-up window
• Import assistance automatically creates and organizes import declarations
• Code formatting

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JDT UI

JDT UI implements Java-specific workbench contributions:

• Package Explorer
• Type Hierarchy View
• Java Outline View
• Wizards for creating Java elements

The JDT UI provides refactoring support like: Extract Method or Safe Rename for Java elements that also updates references. Users can preview (and veto) individual changes stemming from a refactoring operation.

JDT searching support implements precise searches like find declarations of and/or references to packages, types, methods, and fields, scoped to the workspace, a working set, or the current selection.

JDT compare support implements a structured compare of Java compilation units showing the changes to individual Java methods. It supports to replace individual Java elements with version of element in the local history.