org.apache.velocity.tools.generic
Class Alternator

java.lang.Object
  org.apache.velocity.tools.generic.Alternator

public class Alternator
extends java.lang.Object

Utility class for easily alternating over values in a list.

Example usage:

 java...
      String[] myColors = new String[]{"red", "blue"};
      context.put("color", new Alternator(myColors));
      String[] myStyles = new String[]{"hip", "fly", "groovy"};
      // demonstrate manual alternation with this one
      context.put("style", new Alternator(false, myStyles));

 template...
      #foreach( $foo in [1..5] )
       $foo is $color and $style.next
      #end

 output...
      1 is red and hip
      2 is blue and fly
      3 is red and groovy
      4 is blue and hip
      5 is red and fly
 

Since:

Velocity Tools 1.2

Version:

$Id: Alternator.java 477914 2006-11-21 21:52:11Z henning $

Field Summary

private boolean	auto
private int	index
private java.lang.Object[]	list

Constructor Summary

Alternator(boolean auto, java.util.List list)
Creates a new Alternator for the specified list with the specified automatic shifting preference.

Alternator(boolean auto, java.lang.Object[] list)
Creates a new Alternator for the specified list with the specified automatic shifting preference.

Alternator(java.util.List list)
Creates a new Alternator for the specified list.

Alternator(java.lang.Object[] list)
Creates a new Alternator for the specified list.

Method Summary

java.lang.Object	getCurrent() Returns the current item without shifting the list index.
java.lang.Object	getNext() Returns the current item, then shifts the list index.
boolean	isAuto()
void	setAuto(boolean auto) If set to true, the list index will shift automatically after a call to toString().
void	shift() Manually shifts the list index.
java.lang.String	toString() Returns a string representation of the current item or null if the current item is null.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

list

private java.lang.Object[] list

index

private int index

auto

private boolean auto

Constructor Detail

Alternator

public Alternator(java.util.List list)

Creates a new Alternator for the specified list. Alternation defaults to automatic.

Alternator

public Alternator(java.lang.Object[] list)

Creates a new Alternator for the specified list. Alternation defaults to automatic.

Alternator

public Alternator(boolean auto,
                  java.util.List list)

Creates a new Alternator for the specified list with the specified automatic shifting preference.

Parameters:

auto - See setAuto(boolean auto).

list - The (non-null) list of elements to alternate.

Alternator

public Alternator(boolean auto,
                  java.lang.Object[] list)

Creates a new Alternator for the specified list with the specified automatic shifting preference.

Parameters:

auto - See setAuto(boolean auto).

list - The (non-null) list of elements to alternate.

Method Detail

isAuto

public boolean isAuto()

Returns:

Whether this Alternator shifts the list index automatically after a call to toString().

setAuto

public void setAuto(boolean auto)

If set to true, the list index will shift automatically after a call to toString().

shift

public void shift()

Manually shifts the list index. If it reaches the end of the list, it will start over again at zero.

getCurrent

public java.lang.Object getCurrent()

Returns the current item without shifting the list index.

getNext

public java.lang.Object getNext()

Returns the current item, then shifts the list index.

toString

public java.lang.String toString()

Returns a string representation of the current item or null if the current item is null. If auto is true, this will shift after returning the current item.

Overrides:

toString in class java.lang.Object