An Alternator is an iterator to alternate between a couple values or even a list, if it reaches the end of the list, it will start over again at zero.
Methods
| Method | Return Value | Description |
|---|---|---|
make(List list) | Alternator | Returns an iterator that alternates through the list passed in. |
make(boolean auto, List list) | Alternator | Returns an iterator that alternates through the list passed in. The auto boolean determines if it alternates automatically. |
make(Object[] array) | Alternator | Returns an iterator that alternates through the array of objects passed in. |
make(boolean auto, Object[] array) | Alternator | Returns an iterator that alternates through the array of objects passed in. The auto boolean determines if it alternates automatically. |
make(Object o1, Object o2) | Alternator | Returns an iterator that alternates between the objects passed in. |
make(boolean auto, Object o1, Object o2) | Alternator | Returns an iterator that alternates between the objects passed in. The auto boolean determines if it alternates automatically. |
Examples
Example 1: This creates an alternator for switching between red and blue.
#set( $color = $alternator.make('red', 'blue') )
Example 2: This creates an alternator to iterate through the list (hip, fly, groovy)
#set( $style = $alternator.make(false, ['hip','fly','groovy']) )
Example 3: You can send as a parameter, an array or a collection, in addition can set a configuration property called “auto”, if it is true anytime the iterator is referrer will print the current value and move to the next one, for instance:
#set( $numbers = $alternator.make(true, '1', '2') )
$numbers <br/>
$numbers <br/>
$numbers <br/>
$numbers <br/>
$numbers <br/>
The output will be
1
2
1
2
1
Example 4: Now if the “auto” is on false, such as
#set( $numbers = $alternator.make(false, '1', '2') )
The output will be
1
1
1
1
1
Example 5: In order to alternate between values you have to call next, such as
#set( $numbers = $alternator.make(false, '1', '2') )
$numbers.next <br/>
$numbers.next <br/>
$numbers.next <br/>
$numbers.next <br/>
$numbers.next <br/>
Toolbox.xml Configuration
The following example shows how the Alternator Viewtool is mapped in the toolbox.xml file:
<tool>
<key>alternator</key>
<scope>application</scope>
<class>org.apache.velocity.tools.generic.AlternatorTool</class>
</tool>