## Tips and Tricks

### Editing source

Content assist | Content assist provides you with a list of suggested completions for partially entered strings. In the Java editor press Ctrl+Space or invoke Edit > Content Assist.
Content assist in Javadoc comments | Content assist is also available in Javadoc comments.
Suppress types in code assist | To exclude certain types from appearing in content assist, use the type filter feature configured on the Java > Type Filters preference page. Types matching one of these filter patterns will not appear in the Open Type dialog and will not be available to code assist, quick fix and organize imports. These filter patterns do not affect the Package Explorer and Type Hierarchy views.
Content assist for variable, method parameter and field name completions | You can use content assist to speed up the creation of fields, method parameters and local variables. With the cursor positioned after the type name of the declaration, invoke Edit > Content Assist or press Ctrl+Space. If you use a name prefix or suffix for fields, local variables or method parameters, be sure to specify this in the Code Style preference page (Window > Preferences > Java > Code Style).
Parameter Hints | With the cursor in a method argument, you can see a list of parameter hints. In the Java Editor press Ctrl+Shift+Space or invoke Edit > Parameter Hints.
Content assist on anonymous classes | Content assist also provides help when creating an anonymous class. With the cursor positioned after the opening bracket of a class instance creation, invoke Edit > Content Assist or press Ctrl+Space. This will create the body of the anonymous inner class including all methods that need to be implemented.
Toggle between inserting and replacing code assist | When code assist is invoked on an existing identifier, code assist can either replace the identifier with the chosen completion or do an insert. The default behavior (overwrite or insert) is defined in Window > Preferences > Java > Editor > Code Assist. You can temporarily toggle the behavior while inside the content assist selection dialog by pressing and holding the Ctrl key while selecting the completion.
Incremental content assist | Check Insert common prefixes automatically on the Java > Editor > Syntax preference tab to use shell-style incremental completion in the Java editor. If the available completions do not have a common prefix, the proposal popup is displayed.
Create Getter and Setters dialog | To create getter and setter methods for a field, select the field's declaration and invoke Source > Generate Getter and Setter. If you use a name prefix or suffix be sure to specify this in the Code Style preference page (Window > Preferences > Java > Code Style)
Use content assist to create Getter and Setters | Another way to create getters and setters is using content assist. Set the cursor in the type body between members and press Ctrl+Space to get the proposals that create a getter or setter method stub.
Delete Getters and Setters together with a field | When you delete a field from within a view, Eclipse can propose deleting its Getter and Setter methods. If you use a name prefix or suffix for fields, be sure to specify this in the Code Style preference page (Window > Preferences > Java > Code Style).
Create delegate methods | To create a delegate method for a field select the field's declaration and invoke Source > Generate Delegate Methods. This adds the selected methods to the type that contains a forward call to delegated methods. This is an example of a delegate method: ``
Use Drag & Drop for refactoring | You can move Java compilation units between packages by Drag & Drop - all missing imports will be added and references updated.
Use Drag & Drop to move and copy Java code elements | You can move and copy Java elements such as methods and fields by Drag & Drop. This will not trigger refactoring - only the code will be copied or moved.
Use Templates to create a method | You can define a new template (Preferences > Java > Editor > Templates) that contains a method stub. Templates are shown together with the Content Assist (Ctrl+Space) proposals. There are also existing templates, such as 'private_method', 'public_method', 'protected_method' and more. Use the Tab key to navigate between the values to enter (return type, name and arguments).
Use Quick Fix to create a new method | Start with the method invocation and use Quick Fix (Ctrl+1) to create the method.
Use Quick Fix to change a method signature | Add an argument to a method invocation at a call site. Then use Quick Fix (Ctrl+1) to add the required parameter in the method declaration.
Use Content Assist to create a constructor stub | At the location where you want to add the new constructor, use code assist after typing the first letters of the constructor name.
Create new fields from parameters | Do you need to create new fields to store the arguments passed in the constructor? Use quick assist (Ctrl + 1) on a parameter to create the assignment and the field declation and let Eclipse propose a name according to your Code Style preferences.
Use Content Assist to override a method | Invoke Content Assist (Ctrl+Space) in the type body at the location where the method should be added. Content assist will offer all methods that can be overridden. A method body for the chosen method will be created.
Use Quick Fix to add unimplemented methods | To implement a new interface, add the 'implements' declaration first to the type. Even without saving or building, the Java editor will underline the type to signal that methods are missing and will show the Quick Fix light bulb. Click on the light bulb or press Ctrl+1 (Edit > Quick Fix) to choose between adding the unimplemented methods or making your class abstract.
Override a method from a base class | To create a method that overrides a method from a base class: Select the type where the methods should be added and invoke Source > Override / Implement Methods. This opens a dialog that lets you choose which methods to override.
Rename in File | To quickly do a rename that doesn't require full analysis of dependencies in other files, use the 'rename in file' Quick Assist. In the Java Editor, position the cursor in an identifier of a variable, method or type and press Ctrl+1 (Edit > Quick Fix) The editor is switched to the linked edit mode (like templates) and changing the identifier simultaneously changes all other references to that variable, method or type.
Use Quick Fix to handle exceptions | Dealing with thrown exceptions is easy. Unhandled exceptions are detected while typing and marked with a red line in the editor. Click on the light bulb or press Ctrl+1 to surround the call with a try catch block. If you want to include more statements in the try block, select the statements and use Source > Surround With try/catch Block. You can also select individual statements by using Edit > Expand Selection to and selecting Enclosing, Next or Previous. If the call is already surrounded with a try block, Quick Fix will suggest adding the catch block to the existing block. If you don't want to handle the exception, let Quick Fix add a new thrown exception to the enclosing method declaration At any time you can convert a catch block to a thrown exception. Use Ctrl+1 (Edit > Quick Fix) on a catch block.
Less typing for assignments | Instead of typing an assignment, start with the expression that will be assigned. Now use Ctrl+1 (Edit > Quick Fix) and choose 'Assign statement to new local variable' and Quick Assist will guess a variable name for you.
Less work with cast expressions | Don't spend too much time with typing casts. Ignore them first and use quick assist to add them after finishing the statement. For example on assignments: Or in for method arguments: Or for method call targets
Surround lines | To surround statements with an if / while / for statement or a block, select the lines to surround and press Ctrl+1 (Edit > Quick Fix). This lists all templates that contain the variable ${line_selection}. Templates can be configured on Window > Preferences > Java > Editor > Templates. Edit the corresponding templates or define your own templates to customize the resulting code.
Create your own templates | To create your own templates, go to the Java > Editor > Templates preference page and press the New button to create a template. For example, a template to iterate backwards in an array would look like this:
    for (int ${index} = ${array}.length - 1; ${index} >= 0; ${index}--){
       ${cursor}
    }
Code assist can insert argument names automatically | You can have code assist insert argument names automatically on method completion. This behavior can be customized on the Java > Editor > Code Assist preference page (see the Fill argument names on method completion checkbox.) For example, when you select the second entry here, code assist will automatically insert argument names: you can then use the Tab key to navigate between the inserted names. Code assist can also guess argument names - based on their declared types. This can be configured by the Guess filled argument names checkbox on the Java > Editor > Code Assist preference page.
Remove surrounding statement | To remove a surrounding statement or block, position the cursor at the opening bracket and press Ctrl+1 (Edit > Quick Fix).
How was that word spelled again? | You can enable spell-checking support in the Java editor on the Java > Editor > Spelling preference page. Spelling errors are displayed in the Java editor and corresponding Quick Fixes are available: You can make the dictionary also available to the content assist. However, there is currently no dictionary included in Eclipse. The required format is just a list of words separated by newlines and the Quick Fixes allow you to add new words to the dictionary on-the-fly. Contributions of dictionaries would be welcome.
Structured selections | You can quickly select Java code syntactically using the Structured Selection feature. Highlight the text and press Alt+Shift+Arrow Up or select Edit > Expands Selection To > Enclosing Element from the menu bar - the selection will be expanded to the smallest Java-syntax element that contains the selection. You can then further expand the selection by invoking the action again.
Find the matching bracket | To find a matching bracket select an opening or closing bracket and press Ctrl+Shift+P (Navigate > Go To > Matching Bracket). You can also double click before an opening or after a closing bracket - this selects the text between the two brackets.
Smart Javadoc | Type '/**' and press Enter. This automatically adds a Javadoc comment stub containing the standard @param, @return and @exception tags. The templates for the new comment can be configured in Window > Preferences > Java > Code Style > Code Templates
Use the local history to revert back to a previous edition of a method | Whenever you edit a file, its previous contents are kept in the local history. Java tooling makes the local history available for Java elements, so you can revert back to a previous edition of a single method instead of the full file. Select an element and use Replace With > Local History to revert back to a previous edition of the element.
Use the local history to restore removed methods | Whenever you edit a file, its previous contents are kept in the local history. Java tooling makes the local history available for Java elements, so you can restore deleted methods selectively. Select a container and use Restore from Local History to restore any removed members.
Customizable code generation | The Java > Code Style > Code Templates preference page allows you to customize generated code and comments in a similar way to normal templates. These code templates are used whenever code is generated. (These new templates replace the 'filecomment' and 'typecomment' templates previously used for code generation in R2.1.) The check box 'Automatically add comments...' allows you to decide if features that create new methods or types add comments automatically or if they are added explicitly with 'Add Javadoc Comment'.
Sort members | You can Sort Members of a Java compilation unit according to a category order defined in the Java > Appearance > Members Sort Order preference page. You'll find the action under Source > Sort Members
Wrap Strings | You can have String literals wrapped when you edit them. For example, if you have code like this:
    String message= "This is a very long message.";
position your caret after the word "very" and press Enter. The code will be automatically changed to:
    String message= "This is a very" +
               " long message.";
This behavior can be customized in the Java > Editor > Typing preference page.
Smart Typing and how to control it | The Java editor's Smart Typing features ease your daily work. You can configure them on the Typing tab of the Java > Editor preference page. Note that the Smart semicolon positioning and Smart brace positioning are disabled by default. When Close brackets and parenthesis is enabled, you usually have to press an additional key to position the cursor behind the automatically inserted bracket or parenthesis before entering an opening brace or semicolon. Smart semicolon positioning and Smart brace positioning automatically position the semicolon or brace behind the inserted bracket or parenthesis. You can undo this automatic positioning by pressing backspace right afterwards.
Fix your code indentation with one key stroke | A useful feature is Source > Correct Indentation. Select the code where the indents are incorrect and invoke the action.
Quick menus for source and refactoring actions | The refactoring and source actions can be accessed via a quick menu. Select the element to be manipulated in the Java editor or in a Java view and press Alt+Shift+S for the quick source menu or Alt+Shift+T for the quick refactor menu.
Find unused code | The Java compiler detects unreachable code, unused variables, parameters, imports and unused private types, methods and fields. The setting is on the Java > Compiler preference page. These settings are also detected as you type and a quick fix is offered to remove the unneeded code.
Javadoc comment handling | The Eclipse Java compiler can process Javadoc comments. Search reports references in doc comments, and refactoring updates these references as well. This feature is controlled from the Java > Compiler > Javadoc preference tab (or set for an individual project using Project > Properties > Java Compiler > Javadoc). When turned on, malformed Javadoc comments are marked in the Java editor and can be fixed using Edit > Quick Fix (Ctrl+1):

### Searching

Locate variables and their read/write access | You can locate variables and see their read/write status by selecting an identifier (variable, method or type reference or declaration) and invoking Search > Occurrences in File. This marks all references of this identifier in the same file. The results are also shown in the search view, along with icons showing the variable's read or write access. Alternatively, use the new Mark Occurrences feature to dynamically highlight occurrences. You can search over several files by using the general search features (Search > References).
Search for methods with a specific return type | To search for methods with a specific return type, use "* <return type>" as follows: Open the search dialog and click on the Java Search tab. Type '*' and the return type, separated by a space, in the Search string. Select the Case sensitive checkbox. Select Method and Declarations and then click Search.
Remove Javadoc results from Java search | By default Java Search finds references inside Java code and Javadoc. If you don't want to find references inside Javadoc, you can disable this behavior by unchecking Process Javadoc comments of Java > Compiler > Javadoc preference page.
Trace method call chains with the Call Hierarchy | Have you ever found yourself searching for references to methods again and again? Use the new Call Hierarchy to follow long or complex call chains without losing the original context: Just select a method and invoke Navigate > Open Call Hierarchy (Ctrl+Alt+H).

### Code navigation and reading

Open on a selection in the Java editor | There are two ways that you can open an element from its reference in the Java editor. Select the reference in the code and press F3 (Navigate > Open Declaration) Hold Ctrl and move the mouse pointer over the reference The hyperlink style navigation can be configured in Preferences > Java > Editor > Navigation.
In-place outlines | Press Ctrl+F3 in the Java editor to pop up an in-place outline of the element at the current cursor position. Or press Ctrl+O (Navigate > Quick Outline) to pop up an in-place outline of the current source file.
In-place outlines show inherited members | Press Ctrl+O or Ctrl+F3 again to add inherited members to an open In-place outline. Inherited members have a gray label. Filter and sort the outline with the menu in the upper right corner.

In-place hierarchy | Find out which are the possible receivers of a virtual call using the 'quick hierarchy'. Place the cursor inside the method call and press Ctrl+T (Navigate > Quick Hierarchy). The view shows all types that implement the method with a full icon. Press Ctrl+T again to switch to the Supertype hierarchy.
Advanced highlighting | The Java editor can highlight source code according to its semantics (for example: static fields, local variables, static method invocations). When advanced highlighting is enabled via the Java > Editor > Syntax preference tab, the advanced highlighting options show up in the list. There are also options for highlighting operators and brackets.
Initially folded regions | The Default Java Folding allows you to define the initally folded regions on the Folding tab of the Java > Editor preference page. The options supported are: comments, inner types, methods and imports.
Mark occurrences | When working in the editor, turn on Mark Occurrences in the toolbar ( ) or press (Alt+Shift+O). You'll see within a file, where a variable, method or type is referenced. Selecting a return type shows you the method's exit points. Select an exception to see where it is thrown. Fine tune 'mark occurrences' on Preferences > Java > Editor > Mark Occurrences..
Go to next / previous method | To quickly navigate to the next or previous method or field, use Ctrl+Shift+Arrow Up (Navigate > Go To > Previous Member) or Ctrl+Shift+Arrow Down (Navigate > Go To > Next Member)
Control your navigation between annotations | Use the Next / Previous Annotation toolbar buttons or Navigate > Next Annotation (Ctrl+.) and Navigate > Previous Annotation (Ctrl+,) to navigate between annotations in a Java source file. With the button drop-down menus, you can configure on which annotations you want to stop:
Reminders in your Java code | When you tag a comment in Java source code with "TODO" the Java compiler automatically creates a corresponding task as a reminder. Opening the task navigates you back to the "TODO" in the code. Use the Java > Task Tags preference page to configure any other special tags (like "FIXME") that you'd like to track in the task list.
Select variables on endings in Open and Go To dialogs | Open and Go To dialogs now support the end character '<'. To see all types in the Open Type dialog that end with "Test" enter the pattern "*Test<". If '<' is not included in the pattern, a '*' will be appended to the pattern. If you enter "*Test" in the Open Type dialog you will see all types containing "Test" somewhere in the type name.
Make hovers sticky | You can open the text from a hover in a scrollable window by pressing F2 (Edit > Show Tooltip Description). You can select and copy content from this window.
Hovers in the Java editor | You can see different hovers in the Java editor by using the modifier keys (Shift, Ctrl, Alt). When you move the mouse over an identifier in the Java editor, by default a hover with the Javadoc extracted from the corresponding source of this element is shown. Holding down the Ctrl key shows you the source code. You can change this behavior and define the hovers for other modifier keys in Preferences > Java > Editor > Hovers.
Open and configure external Javadoc documentation | If you want to open the Javadoc documentation for a type, method or field with Shift+F2 (Navigate > Open External Javadoc), you first have to specify the documentation locations to the elements parent library (JAR, class folder) or project (source folder). For libraries open the build path page (Project > Properties > Java Build Path), go to the Libraries, expand the node of the library where you can edit the 'Javadoc location' node. The documentation can be local on your file system in a folder or archive or on a web server. For types, methods or fields in source folders, go to the (Project > Properties > Javadoc Location).

### Java views

Declaration view | There is a new Declaration view (Window > Show View > Other > Java > Declaration) which shows the source of the element selected in the Java editor or in a Java view.
Javadoc view | There is a Javadoc view (Window > Show View > Other > Java > Javadoc) which shows the Javadoc of the element selected in the Java editor or in a Java view. The Javadoc view uses the SWT Browser widget to display HTML on platforms which support it.
Type hierarchy view supports grouping by defining type | The type hierarchy method view lets you sort the selected type's methods by its defining types. For example, for AbstractList you can see that it contains methods that were defined in Object, Collection and List:
Tricks in the type hierarchy | Focus the type hierarchy on a new type by pressing F4 (Navigate > Open Type Hierarchy) on an element or a selected name. You can open the Hierarchy view not only on types but also on packages, source folders, JAR archives and Java projects. You can Drag & Drop an element onto the Hierarchy view to focus it on that element. You can change the orientation (from the default vertical to horizontal) of the Hierarchy view from the view's toolbar menu.
Find out where a method is implemented in the hierarchy | To find out which types in a hierarchy override a method, use the 'Show Members in Hierarchy' feature. Select the method to look at and press F4 (Navigate > Open Type Hierarchy). This opens the type hierarchy view on the method's declaring type. With the method selected in the Hierarchy view, press the 'Lock View and Show Members in Hierarchy' tool bar button. The hierarchy view now shows only types that implement or define the 'locked' method. You can for example see that 'isEmpty()' is defined in 'List' and implemented in 'ArrayList' and 'Vector' but not in 'AbstractList'.
Hierarchical vs. flat layout of packages | An option on the Java Packages view (and Package Explorer view) allows you to change the way packages are displayed. Hierarchical displays packages in a tree, with sub-packages below packages; Flat displays them in the standard arrangement, as a flat list with all packages and sub-packages as siblings.
Logical packages | The Java Packages view (Java Browsing perspective) coalesces packages of the same name across source folders within a project. This shows the Packages view containing a logical package.
Compress package names | If your package names are very long you can configure a compressed name that appears in the viewers. Configuration of the compression pattern is done in Preferences > Java > Appearance Using this example, packages are rendered the following way:

### Various

JUnit | Select a JUnit test method in a view and choose Run > JUnit Test from the context menu or Run > Run As > JUnit Test from the main menu. This creates a launch configuration to run the selected test.
Hide JUnit view until errors or failures occur | You can make the JUnit view open only when there are errors or failures. That way, you can have the view set as a fast view and never look at it when there are no failing tests. While there are no problems in your tests you will see this icon (the number of small green squares will grow, indicating progress) while running them and this icon after they are finished. If, however, errors or failures occur, the icon will change to (or if tests are finished) and the JUnit view will appear. This behavior can be configured via the Java > JUnit preference page.
Content assist in dialog fields | Content Assist (Ctrl+Space) is now also available in input fields of various Java dialogs. Look for small light bulb icon beside the field when it has focus. Content Assist is e.g. implemented in the New Java Class, New Java Interface, and New JUnit Test wizards, as well as in the refactoring dialogs for Change Method Signature and moving static members. The Extract Local Variable, Convert Local Variable to Field, and Introduce Parameter refactorings offer content assist proposals for the new element name.
Structural compare of Java source | A structural comparison of Java source ignores the textual order of Java elements like methods and fields and shows more clearly which elements were changed, added, or removed. For initiating a structural comparison of Java files you have two options: Select two Java compilation units and choose Compare With > Each Other from the view's context menu. If the files have differences, they are opened into a Compare Editor. The top pane shows the differing Java elements; double clicking on one of them shows the source of the element in the bottom pane. In any context where a file comparison is involved (e.g. a CVS Synchronization) a double click on a Java file not only shows the content of the file in a text compare viewer, but it also performs a structural compare and opens a new pane showing the results. You can even ignore comments and formatting changes when performing the structural compare: turn on the Ignore Whitespace option via the Compare Editor's toolbar button, or the CVS Synchronization View's drop down menu.
Structural compare of property files | A structural comparison of Java property files (extension: .properties) ignores the textual order of properties and shows which properties were changed, added, or removed. For initiating a structural comparison of property files you have two options: Select two files in the Package Explorer or Navigator and choose Compare With > Each Other from the view's context menu. If the files have differences, they are opened into a Compare Editor. The top pane shows the affected properties; double clicking on one of them shows the source of the property in the bottom pane. In any context where a file comparison is involved (e.g. a CVS Synchronization) a double click on a property file not only shows the content of the file in a text compare viewer, but it also performs a structural compare and opens a new pane showing the results.
Define prefixes or suffixes for fields, parameters and local variables | In addition to configuring the prefix or suffix for fields, you can also specify the prefix or suffix for static fields, parameters, and local variables. These settings on the Java > Code Style preference page are used in content assist, quick fix, and refactoring whenever a variable name is computed.
Organize Imports works on more than single files | You can invoke Organize Imports on sets of compilation units, packages, source folders or Java projects.
Format more than one file | Select all Java files to format and choose Source > Format to format them all. The format action is also available on packages, source folders or Java projects.
Use project specific compiler settings | Each project can use the global compiler settings or you can define project specific settings. Select the project and open the Java compiler page in the project properties (Project > Properties > Java Compiler) You can also configure project specific settings for the Java Task tags (TODO tasks).
Use a specific JRE for a project | When creating new projects the JRE that is added by default is the one selected in Preferences > Java > Installed JRE's. To set a project specific JRE, open the project's Java Build path property page (Project > Properties > Java Build Path), then the Libraries page, select 'JRE System Library' and press Edit. In the 'Edit Library' dialog you can select either the default JRE or a project specific JRE to add to new projects.
Propagating deprecation tag | The Java compiler can be configured to diagnose deprecation using options on the Java > Compiler > Advanced page. Using this configuration, the result is: If you're unable to fix a usage of a deprecated construct, we recommend that you tag the enclosing method, field or type as deprecated. This way, you acknowledge that you did override a deprecated construct, and the deprecation flag is propagated to further dependents.
Recovering from abnormal inconsistencies | In the rare event of a dysfunction, JDT could reveal some inconsistencies such as: missing results in a Java Search or Open Type invalid items in package explorer To make it consistent again, the following actions need to be performed in this exact order: Close all projects using navigator Close Project menu action Exit and restart Eclipse Open all projects using navigator Open Project menu action Manually trigger a clean build of entire workspace (Project > Clean...)

### Debugging

Launching from the Context Menu | Launching is now available from the context menu of many items. You can launch from a source file, package, method, type, etc. by choosing Run (or Debug) > Java Application from the context menu.
Evaluations in the debugger | Snippet evaluation is available from a number of places in the debugger. Choosing Display or Inspect from the context menu of the editor or Variables view will show the result in a pop-up whose result can be sent to the Display or Expressions views.
View Management in Non-Debug perspectives | The Debug view automatically manages debug related views based on the view selection (displaying Java views for Java stack frames and C views for C stack frames, for example). By default, this automatic view management only occurs in the Debug perspective, but you can enable it for other perspectives via the View Management preference page available from the Debug view toolbar pulldown.
Environment Variables | You can now specify the environment used to launch Java applications via the Environment tab.
String Substitutions | Variables are now supported for many parameters of Java Application launch configurations. Most fields that support variables have a Variables... button next to them. The Main Type field supports variables as well; the ${java_type_name} variable allows you to create a configuration that will run the selected type.
Logical Structures | The Logical Structures toggle on the Variables view toolbar presents alternate structures for common types. JDT provides logical views for Maps, Collections, and SWT Composites.
Default VM Arguments | If you specify the same arguments to a certain VM frequently, you can configure Default VM Arguments in the Installed JREs preference page. This is more convenient than specifying them for each launch configuration.
Stop in Main | You can use Stop in main in a Java Application launch configuration to cause your program to stop at the first executable line of the main method when you run it under debug mode.
Conditional breakpoints | You can use conditional breakpoints in Breakpoint Properties... to control when a breakpoint actually halts execution. You can specify whether you want the breakpoint to suspend execution only when the condition is true, or when the condition value changes.
Disabling breakpoints | If you find yourself frequently adding and removing a breakpoint in the same place, consider disabling the breakpoint when you don't need it and enabling it when needed again. This can be done using Disable Breakpoint in the breakpoint context menu or by unchecking the breakpoint in the Breakpoints view. You can also temporarily disable all breakpoints using the Skip All Breakpoints action in the Breakpoints view toolbar. This will tell the debugger to skip all breakpoints while maintaining their current enabled state.
Changing variable values | When a thread is suspended in the debugger, you can change the values of Java primitives and Strings in the Variables view. From the variable's context menu, choose Change Variable Value. You can also change the value by typing a new value into the Details pane and using the Assign Value action in the context menu (CTRL-S key binding).
Variable values in hover help | When a thread is suspended and the cursor is placed over a variable in the Java editor, the value of that variable is displayed as hover help.
Drop to Frame | When stepping through your code, you might occasionally step too far, or step over a line you meant to step into. Rather than restarting your debug session, you can use the Drop to Frame action to quickly go back to the beginning of a method. Select the stack frame corresponding to the Java method you wish to restart, and select Drop to Frame from Debug view toolbar or the stack frame's context menu. The current instruction pointer will be reset to the first executable statement in the method. This works for non-top stack frames as well. Note that Drop to frame is only available when debugging with a 1.4 or higher VM, or the J9 VM. There are some situations where a JVM may be unable to pop the desired frames from the stack. For example, it is generally impossible to drop to the bottom frame of the stack or to any frame below a native method.
Hot code replace | The debugger supports Hot Code Replace when debugging with a 1.4 or higher VM, or the J9 VM. This lets you make changes to code you are currently debugging. Note that some changes such as new or deleted methods, class variables or inner classes cannot be hot swapped, depending on the support provided by a particular VM.
Stepping into selections | The Java debugger allows you to step into a single method within a series of chained or nested method calls. Simply highlight the method you wish to step into and select Step into Selection from the Java editor context menu. This feature works in places other than the currently executing line. Try debugging to a breakpoint and stepping into a method a few lines below the currently instruction pointer.
Controlling your console | Output displayed in the console can be locked to a specific process via the Pin Console action in the Console view toolbar. There's also a Scroll Lock action that stops the console from automatically scrolling as new output is appended.
Creating watch items | A watch item is an expression in the Expressions view whose value is updated as you debug. You can create watch items from the Java editor by selecting an expression or variable and choosing Watch from its context menu or the top-level Run menu.
Watch points | A watch point is a breakpoint that suspends execution whenever a specified variable is accessed or modified. To set a watchpoint, select a variable in the Outline view and choose Toggle Watchpoint from its context menu. To configure a watchpoint, select the watchpoint in the Breakpoints view and choose Properties... from its context menu. The most important properties for this type of breakpoint are the Access and Modification checkboxes which control when the breakpoint can suspend execution.
Threads and Monitors view | The debugger's Threads and Monitors view shows which threads are holding locks and which are waiting to acquire locks.
Step filters | Step filters prevent the debugger from suspending in specified classes and packages when stepping into code. Step filters are established in Window > Preferences > Java > Debug > Step Filtering. When the Use Step Filters togggle (on the debug toolbar and menu) is on, step filters are applied to all step actions. In the Debug view, the selected stack frame's package or declaring type can be quickly added to the list of filters by selecting Filter Type or Filter Package from the stack frame's context menu.
Using the scrapbook | If you want to experiment with API or test out a new algorithm, it's frequently easier to use a Java scrapbook page than create a new class. A scrapbook page is a container for random snippets of code that you can execute at any time without a context. To create a scrapbook page, create a new file with a .jpage extension (or use the New wizard - Java > Java Run/Debug > Scrapbook Page). Enter whatever code you wish to execute, then select it. There are three ways to execute your code: Execute the selected code and place the returned result in the Expressions view Execute the selected code and place the String result right in the scrapbook page Execute the selected code (and ignore any returned result) These actions are in the workbench toolbar and also in the scrapbook page's context menu.
Editing launch configurations | Holding down the Ctrl key and making a selection from the Run or Debug drop-down menu opens the associated launch configuration for editing. The launch configuration can also be opened from the context menu associated with any item in the Debug view.
Favorite launch configurations | Launch configurations appear in the Run/Debug drop-down menus in most recently launched order. However it is possible to force a launch configuration to always appear at the top of the drop-downs by making the configuration a 'favorite'. Use the Organize Favorites... action from the appropriate drop down menu to configure your favorite launch configurations.
Detail formatters | In the Variables & Expressions views, the detail pane shows an expanded representation of the currently selected variable. By default, this expanded representation is the result of calling toString() on the selected object, but you can create a custom detail formatter that will be used instead by choosing New Detail Formatter from the variable's context menu. This detail formatter will be used for all objects of the same type. You can view and edit all detail formatters in the Java > Debug > Detail Formatters preference page.
Running code with compile errors | You can run and debug code that did not compile cleanly. The only difference between running code with and without compile errors is that if a line of code with a compile error is executed, one of two things will happen: If the 'Suspend execution on compilation errors' preference on the Java > Debug preference page is set and you are debugging, the debug session will suspend as if a breakpoint had been hit. Note that if your VM supports Hot Code Replace, you could then fix the compilation error and resume debugging Otherwise, execution will terminate with a 'unresolved compilation' error It is important to emphasize that as long as your execution path avoids lines of code with compile errors, you can run and debug just as you normally do.
Word wrap in Variables view | The details area of the debugger's Variables and Expressions views supports word wrap, available from the view drop-down menu.
Code assist in the debugger | Code assist is available in many contexts beyond writing code in the Java editor: When entering a condition for a breakpoint In the Details pane of the Variables & Expressions view When entering a Details Formatter code snippet When entering code in a Scrapbook page In the Display view
Command line details | You can always see the exact command line used to launch a program in run or debug mode by selecting Properties from the context menu of a process or debug target, even if the launch has terminated.
Stack trace hyperlinks | Java stack traces in the console appear with hyperlinks. When you place the mouse over a line in a stack trace, the pointer changes to the hand and the stack trace is underlined. Pressing the mouse button opens the associated Java source file and positions the cursor at the corresponding line. Pressing the mouse button on the exception name at the top of the stack trace will create an exception breakpoint.