View source for FAQ How can Content Assist make me the fastest coder ever?

When extending Eclipse, plug-in authors are confronted with an overwhelming selection
of API to choose from. In the good old days, books could be published with
API references, and programmers could study the material and recite the proper
incantations to drive the relatively simple APIs. With modern APIs, this is
no longer possible. There simply is too much to read and remember. 
Content Assist to the rescue!



Content Assist can take the guesswork out of coding in a number of ways:


* <i>Finding a given type</i>.
Assume that you are writing some code and want to use a button in your UI. You start typing the letter
&#147;B&#148; and don&#146;t remember the rest of the word. Simply press Ctrl+Space,
and the Java tooling will present you with a list of all types that start with the
letter &#147;B.&#148; The list starts with <tt>Boolean</tt>. Keep typing, and the list narrows
down. After typing <tt>But</tt>, you get to choose between 
<tt>java.awt.Button</tt> and <tt>org.eclipse.swt.widgets.Button</tt>. 
Choose the one you like, and the editor  inserts
the class <i>and</i> inserts an import statement for the class at the same time.




* <i>Finding a given field or method</i>. 
After typing a dot after a certain 
expression, Content Assist will suggest all possible fields and methods 
applicable to the expression&#146;s result type. This functionality is very useful
for discovering what operations can be applied to a given object. Combined with
pervasive use of getters and setters, browsing an API is really
simple. For the <tt>Button</tt> example, continuations for <tt>get</tt> show
all attributes that can be obtained from a button. The ones starting with
<tt>set</tt> show the attributes that can be modified. Another frequent prefix used
while writing plug-ins is <tt>add</tt> to add event listeners. Having Content Assist at
your fingertips definitely improves coding speed by combining intuition 
with content-assisted browsing.



* <i>Entering method parameter values</i>. 
When entering Ctrl+Space
after the &#147;(&#148; for a method call, Content Assist will provide the 
expected type name for each parameter. When you advance to the next
parameter&#151;by pressing a comma&#151;the Content Assist hints move along with you.
This is especially useful for overloaded methods with ambiguous signatures
and for methods with many parameters.



* <i>Overriding inherited methods</i>. 
Invoke Content Assist when
the cursor is between method declarations. Proposals will be
shown for all possible methods that can be overridden from
superclasses.



* <i>Generating getters and setters</i>. 
Between two method
declarations, type <tt>get</tt>, and invoke Content Assist.
Proposals will be shown for creating accessor methods for any
fields in the class that do not yet have an accessor. The same
applies for generating setter methods by invoking Content
Assist on the prefix <tt>set</tt>.



* <i>Creating anonymous inner classes</i>. 
Eclipse likes loose coupling and
hence works a lot with listeners that are registered on demand. The listeners
implement a given interface with methods that are called when the 
event of interest happens.
Typical usage is to declare an anonymous inner class, as in this example:
<pre>
button.addSelectionListener(new SelectionAdapter() {
    public void widgetSelected(SelectionEvent e) {
        // do something here
    }
});</pre>
Here is how an experienced Eclipse user might enter that code using
Content Assist. 

 but'''&lt;Ctrl+Space&gt;''' select 'button'
 .add'''&lt;Ctrl+Space&gt;''' select 'addSelectionListener'
 new Sel'''&lt;Ctrl+Space&gt;''' select 'SelectionAdapter'
 () { '''&lt;Ctrl+Space&gt;''' select 'widgetSelected'



Note that Content Assist is also available inside javadoc comments and can help 
when declaring fields and can assist with named local variables and method arguments. 
In [[FAQ How do I add Content Assist to my language editor?]]
we explain how Content Assist is implemented in Eclipse.



Also note that Content Assist can be fully customized from the '''Java &gt; Editor'''
preference page.





== See Also: ==

[[FAQ How can templates make me the fastest coder ever?]]

[[FAQ How do I add Content Assist to my language editor?]]

{{Template:FAQ_Tagline}}