What's New in 3.2

This document contains descriptions of some of the more interesting or significant changes made to the Java development tools for the 3.2 release of Eclipse. It is broken into several sections:

Java developers will also be interested in the corresponding What's new document in the Workbench User Guide.

General Java Tools

Create and apply refactoring scripts

Refactorings executed in one workspace can now be exported and reapplied in other workspaces.

This feature allows you, for example, to make changes to API classes using refactorings (i.e. rename a type) and ship this changes to your clients. Your clients can then reapply the refactorings in there workspaces to prevent API incompatibilities.

Create a script from the refactoring history using Refactor > Create Script...

Create refactoring script

To apply the generated script on an arbitrary workspace use Refactor > Apply Script...

JAR file export with refactorings

You can now include refactoring information into a JAR file during a JAR export.

Use the JAR Export Wizard to export your code together with refactoring information. Access this wizard through File > Export... and select the refactorings to export on the first page of the wizard.

Jar export refactoring selection

Your clients can update there workspaces by using Refactor > Migrate JAR File....

Replace JAR action

This will automatically offer to replay the stored refactoring on the source files in the project.

Refactoring History

A Refactoring History stores the information about refactorings executed in your workspace. You can access and modify this history through Refactor > History...

The refactoring history

JUnit 4 support

Eclipse supports the new JUnit 4 and its improvements. You can write JUnit 4 tests or use the New JUnit Test Case Wizard to generate the tests.

JUnit 4 support

For instance:

  • You can tag a test with @Ignore to ignore the test.
  • Select a JUnit 3 or JUnit 4 test runner in the launch configuration for your tests.

JUnit view history

The JUnit view can now handle multiple concurrent test runs. You can switch between active and recent test runs through the new history. You can rerun tests from the history or rerun a single failed test without stopping already running tests.

JUnit History

This works with JUnit 3 as well as with JUnit 4.

Clean Up Wizard

The Clean Up Wizard helps fixing multiple problems at once and to establish a code style.

For instance, you can:

  • Convert all for loops to enhanced for loops where possible.
  • Mark all overriding methods in a whole project with an @Override annotation.

The wizard is especially helpful when converting Java 1.4 compatible code to Java 5.0.

Picture of Cleanup wizard

Select a project, package, or file and use Source > Clean Up... to start this wizard.

Extract Superclass refactoring

A brand new refactoring called Extract Superclass extracts a common superclass from a set of sibling types. The selected sibling types become direct subclasses of the extracted superclass after applying the refactoring. Moreover, Extract Superclass allows to use the extracted superclass wherever possible in the code.

JavaEditorTests and PropertiesEditorTests are the sibling types in the following example. The first picture shows the type hierarchy before the refactoring.

Picture of Hierarchy before extract EditorTests

The next picture shows the type hierarchy after extracting EditorTests with the Extract Superclass refactoring.

Picture of Hierarchy after extract EditorTests

To invoke this refactoring use Refactor > Extract Superclass....

Introduce Indirection refactoring

Another new refactoring is Introduce Indirection. It lets you redirect all callers of a method to a new method. The new method calls the original one. You can replace the default implementation of the new method by any other if you like.

Such an indirection is useful when new behavior needs to be introduced to a method but:

  • The method cannot be changed because it is from a library.
  • The method must not be changed because it is an API method.

Use the indirection for bug fixes to the original method or as a quick way to add code before or after all calls to a method.

To execute the Introduce Indirection refactoring select a method, invoke Refactor > Introduce Indirection..., provide a name and the declaring class for the new method.

Introduce Indirection - dialog

The method is added to the selected declaring class.

Introduce Indirection - updated reference

And all references are updated to call the new method.

Introduce Indirection - new method

Rename Type updates similarly named elements

The Rename Type refactoring can now rename variables and methods with names similar to the renamed type. This feature helps to keep method and variable names synchronized with type names.

Update Similar Declarations UI

To invoke this refactoring select a type and use Refactor > Rename...

Category support

Categories are a new Java 6.0 feature. Categories can be defined in Javadoc comments for types, methods, and fields using the @category tag.

Picture of Code using categories

Categories are shown in the Outline view, the Quick Outline, and the Members view in the Java Browsing perspective. Also available is a filter to specify which Categories should be shown.

Picture of Outline showing categories and category filters

All these features are available independent of the compiler compliance level.

API aware refactorings

There are a number of existing refactorings which have been extended to support API compatibility by keeping the original member as a delegate to the refactored member:

  • Rename Method
  • Rename Field (for constants only)
  • Move Method
  • Introduce Parameter
  • Change Signature

Picture of Keep original member as delegate to refactored member

The generation of a delegate member to preserve API compatibility can be enabled by checking Keep original method as delegate to renamed method in the refactoring dialog.

Rename Package refactoring renames subpackages

The Rename Package refactoring does now also rename subpackages on request.

Rename Package dialog with new checkbox

In this example, junit.samples.money is renamed to junit.examples.money.

To invoke this refactoring select a package and use Refactor > Rename...

Find Broken Externalized Strings

A new action can search for broken externalized strings. The search reports missing keys, unused keys, and duplicate keys.

Picture of Find Broken Externalized Strings action

To start the search select a properties file, a package, or a whole project and use Source > Find Broken Externalized Strings

Generate hashCode() and equals()

A new action can be used to generate the methods hashCode() and equals(). You can select the fields on which the implementation should be based.

Generate hash and equals wizard

To invoke this action select a type and use Source > Generate hashCode() and equals()...

"Surround With" quick menu

A new quick menu allows to surround a selection of lines with code. The menu is extendable with custom templates. The templates are now aware of variables that need to be pulled out or made final.

Surround with runnable code transformation

To show the menu select a line and use Source > Surround With

You can add your custom templates on the Java > Editor > Templates preference page. All the template needs is a ${line_selection} variable.

Paste type declaration creates new compilation unit

Importing and running a Java snippet from an e-mail or bugzilla has never been easier:

  1. Copy one or more Java type declarations (optionally including package and import declarations) to the clipboard
  2. In the Package Explorer, select a location inside the source folder of the Java project
  3. Choose Edit > Paste (Ctrl+V)

A new Java compilation unit is created with the given source, and the Java editor is opened on it.

When pasting into a package, the package declaration is added/updated to match the location. When pasting directly into a source folder, the package declaration in the copied source defines where the new compilation unit should get created.

File content decorator

Enable the Java Type Indicator on the General > Appearance > Label Decoration preference page to find out what the first type in a compilation unit or class file is.

Picture of Java Type Indicator Label Decorator

Filter for refactoring preview dialog

The refactoring preview page now supports filtering of changes. This is especially helpful when updating textual matches in comments and strings is requested while renaming Java elements.

The filtered preview page

The screen shot shows the rename dialog filtered for textual matches while renaming the class TestCase to TestCasee.

Changes related to the visibility of Java elements can now be filtered as well.

Command line code formatter

It is now possible to format source code without starting the Eclipse UI using the new headless formatter application. The command line formatter works as a standard Eclipse application.

The following command will format the source files in the folder src with the options specified in the config.prefs file:

eclipse -application org.eclipse.jdt.core.JavaCodeFormatter -config d:/config.prefs c:/src

See Help > Java Development User Guide > Tasks > Using the Formatter Application for details.

Support for Java-like extensions

Files with a file extension other than .java and containing pure Java code are now supported. A Java-like extension can be added using the General > Content Types > Text > Java Source File preference.

picture of Java perspective with Y.abc compilation unit

New Quick Fixes

Several new quick fixes have been added, for example:

  • A Quick Fix to fix raw type accesses

      Raw access correction proposal

      The quick fix gleans information from usages within the same file. For a more sophisticated analysis, use the Infer Generic Type Arguments refactoring.

  • A Quick Fix to add a missing annotation attribute

      Quick fix for missing annotation attribute

  • A Quick Fix to add a new annotation member

      Quick fix for new annotation member

Java Editor

Customizable Content Assist

Repeatedly invoking content assist (Ctrl+Space on most platforms) now cycles through different proposal categories.

You can assign separate key shortcuts to your favorite proposal categories and configure which should be shown in the default content assist popup.

Screenshot: Content assist popup with Java proposals; repeated invocation brings up template proposals.

Configure content assist on the Java > Editor > Content Assist > Advanced preference page.

A new extension point allows plug-in writers to contribute completion proposals and categories to the content assist process of the Java editor. See the org.eclipse.jdt.ui.javaCompletionProposalComputer extension point for details.

CamelCase support in code completion

Code completion now supports CamelCase patterns. For example, completing on NPE will propose NullPointerException. This support can be enabled or disabled using the Java > Editor > Content Assist > Show camel case matches preference.

picture of Java editor completing on NPE

Ruler support and outline for Java files outside workspace

The Java editor now shows vertical rulers and the Outline page as well as the Quick Outline shows the outline for external Java files and Java files from repositories.

Picture showing ruler support

All members can be folded

When projection is enabled, fields and initializers and their comments can now be folded away the same way as methods.

Screenshot: A java class with two fields. The javadoc comment of the first and the initializer of the second are folded.

There are new text folding commands for collapsing all comments, collapsing all members, and resetting the folding structure. These commands are found on the Java editor's Folding context menu on the vertical ruler.

Improved support for Eclipse's string externalization mechanism

Eclipse string externalization mechanism has now the same kind of support as traditional string externalization. The associated externalized value is shown in a hover, when you linger over a key for an externalized string in the Java editor.

Picture of NLS hover

Ctrl+Click on the key to navigate directly to the entry in the corresponding properties file. In the properties file editor you can use Ctrl+Click to find out where the key is used in the code.

Javadoc view and tool tips from attached Javadoc

The Javadoc view and the Javadoc hovers now extract the information from the attached Javadoc for libraries that do not have source attached.

Completion in Javadoc comments

Completion is now available in Javadoc comments. The proposals include both: an "@link" proposal and a regular reference proposal.

picture of Java editor with text area Javadoc conpletion

Java Compiler

Java SE 6.0 compliance

The Java SE 6.0 compliance is now fully supported. In particular, StackMapTable attributes (see JSR 202) are now generated in .class files with a 1.6 target.

Setting 6.0 compliance

Null reference analysis

The Java compiler is now capable to perform basic null reference analysis for local variables.

This optional diagnosis can be enabled using the Java > Compiler > Errors/Warnings > Potential programming problems > Null reference preference.

picture of Java editor with null ref warning

Note that the analysis is fairly conservative, aligned on definite assignment rules. It only considers cases where there is something suspicious (e.g., if later on a null check is performed), rather than complaining on all possible cases.

In 5.0 compliance mode, null reference warnings can be silenced using @SuppressWarnings("null").

Improved syntax recovery

The internal Java parser is now much more resilient to syntax errors. In Eclipse 3.1, a syntax error would prevent subsequent errors from being displayed. The parser can now recover from statements with errors and go on to perform further analyzes.

In the following example, the invalid reference to method bar() is detected despite the missing semicolon in the previous statement.

picture of Java editor with syntax recovery

This for example allows refactorings that only affect a single file to tolerate syntax errors. For instance, it is now possible to rename or extract a local variable at the top of a method that has not yet been written completely.

Picture of Extract local variable in incomplete method

Treat configurable Errors as non fatal

The option Java > Compiler > Building > Treat configurable errors as fatal errors controls if a configurable error is intended to be fatal or not. This option is enabled by default.

If this option is disabled then the compiled code can be executed despite the fact that errors exist in the code.

Detection of unnecessary $NON-NLS$ tags

Unnecessary $NON-NLS$ tags are now detected. A problem is reported if a line comment starts with //$NON-NLS-x$ and no corresponding string exists on the same line.

The reporting can be turned on and off using the same preference as for the detection of non-externalized Strings. It can be set using the Java > Compiler > Errors/Warnings > Code Style > Non-externalized strings (missing/unused $NON-NLS tags) preference.

picture of Java editor with unnecessary NLS tag

To remove the unnecessary tags use Quick Fix (Ctrl + 1), or Ctrl + 1, Ctrl + Enter to remove all unnecessary tags within a compilation unit.

Detection of raw type usage

Usages of raw types are now detected. A raw type is a reference to some generic type without any type argument (e.g. List in place of List<Element>).

This optional diagnosis can be enabled independently from unchecked type operations using the Java > Compiler > Errors/Warnings > Generic types > Usage of a raw type preference.

picture of Java editor with usage of a raw type

This warning can be silenced by @SuppressWarnings("unchecked").

Also a Quick Fix has been implemented to help resolving the raw type usage problem.

Detection of method parameter assignments

Assigning to method parameters is considered poor practice.

To detect and report such assignments enabled the Java > Compiler > Errors/Warnings > Code style > Parameter assignment preference.

picture of Java editor with parameter assigment warning

Detection of unused labels

The Java compiler now detects unused statement labels.

This optional diagnosis can be enabled using the Java > Compiler > Errors/Warnings > Unnecessary code > Unused break/continue label preference.

picture of Java editor with usage of a raw type

Detection of switch case fall through

The Java compiler can now detect if a case may be entered by falling through a previous case. Empty cases are allowed.

This optional diagnosis can be enabled using the Java > Compiler > Errors/Warnings > Potential programming problems > Switch case fall through preference.

picture of Java editorwith fall through warning

A quick fix to add a break statement to the previous case has been implemented.

Improved performance for large .jar files

The size limit of the internal Java model cache is now a function of the max heap size (-Xmx VM argument on most JVMs) given to the Java Virtual Machine running the Eclipse IDE.

Raising the heap size has a noticeable performance improvement when there are large .jar files on the build classpath.

Recreating modified .class files

The Java builder can now recreate modified or removed .class files in the output folder using the original source.

This can be controlled using the Java > Compiler > Building > Output folder > Rebuild class files modified by others preference.

Java Debugger
Execution environments

An execution environment describes the capabilities of a runtime - for example, J2SE-1.4. You can specify JREs used for running, debugging and building based by referencing an execution environment. The new Execution Environments preference page displays the JREs installed in your workspace compatible with each execution environment. JREs that meet the exact requirements of an execution environment are displayed in bold, and JREs that surpass the requirements of an environment are displayed in the default font. When more than one JRE is compatible with an execution environment, you can select a default JRE to use for that environment by checking it.

A build path or launch configuration referencing an execution environment is more portable than one referencing an explicit JRE as a JRE's execution environment can be resolved independent of its name. Use the JRE tab or Edit Library wizard to specify an execution environment for running and building.

System property launch variable

A new launch variable allows to dynamically specify system properties as Java program and VM arguments from the Eclipse runtime. The variable accepts a single argument which is the name of the system property to be resolved at launch time.

For example, the java.home system property would be referenced with ${system_property:java.home}.

Evaluation support for arrays

Evaluation and content assist are now supported for Java arrays. Use this to refer to the selected array.

Java thread groups

You can now display thread groups in the Debug View by toggling Show Thread Groups in the view menu.

Runtime classpath exported entries

A runtime classpath can be configured to include only exported entries from the build path. By default, a runtime classpath includes all entries (exported and non-exported).

From the Classpath tab select the default entry and use the Edit... button to configure the option.

Suspend Thread versus Suspend VM

An option has been added to the Java > Debug preference page to control whether newly-created breakpoints suspend a single thread or the entire VM.