EClipse tips and trics2

Submitted by Ahmed Hashim on Sat, 2006-01-14 04:48

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):