org.apache.struts2.components

## Class IteratorComponent

- java.lang.Object
- - org.apache.struts2.components.Component
  - - org.apache.struts2.components.ContextBean
    - - org.apache.struts2.components.IteratorComponent

-     public class IteratorComponent
      extends ContextBean

  Iterator will iterate over a value. An iterable value can be any of: java.util.Collection, java.util.Iterator, java.util.Enumeration, java.util.Map, or an array.

  - status (String) - if specified, an instance of IteratorStatus will be pushed into stack upon each iteration
  - value (Object) - the source to iterate over, must be iteratable, else the object itself will be put into a newly created List (see MakeIterator#convert(Object)
  - id (String) - if specified the current iteration object will be place with this id in Struts stack's context scope
  - begin (Integer) - if specified the iteration will start on that index
  - end (Integer) - if specified the iteration will end on that index(inclusive)
  - step (Integer) - if specified the iteration index will be increased by this value on each iteration. It can be a negative value, in which case 'begin' must be greater than 'end'

  The following example retrieves the value of the getDays() method of the current object on the value stack and uses it to iterate over. The <s:property/> tag prints out the current value of the iterator.

       <s:iterator value="days">
         <p>day is: <s:property/></p>
       </s:iterator>

  The following example uses a `Bean` tag and places it into the ActionContext. The iterator tag will retrieve that object from the ActionContext and then calls its getDays() method as above. The status attribute is also used to create an `IteratorStatus` object, which in this example, its odd() method is used to alternate row colours:

       <s:bean name="org.apache.struts2.example.IteratorExample" var="it">
         <s:param name="day" value="'foo'"/>
         <s:param name="day" value="'bar'"/>
       </s:bean>

       <table border="0" cellspacing="0" cellpadding="1">
       <tr>
         <th>Days of the week</th>
       </tr>

       <s:iterator value="#it.days" status="rowstatus">
         <tr>
           <s:if test="#rowstatus.odd == true">
             <td style="background: grey"><s:property/></td>
           </s:if>
           <s:else>
             <td><s:property/></td>
           </s:else>
         </tr>
       </s:iterator>
       </table>

  The next example will further demonstrate the use of the status attribute, using a DAO obtained from the action class through OGNL, iterating over groups and their users (in a security context). The last() method indicates if the current object is the last available in the iteration, and if not, we need to separate the users using a comma:

        <s:iterator value="groupDao.groups" status="groupStatus">
            <tr class="<s:if test="#groupStatus.odd == true ">odd</s:if><s:else>even</s:else>">
                <td><s:property value="name" /></td>
                <td><s:property value="description" /></td>
                <td>
                    <s:iterator value="users" status="userStatus">
                        <s:property value="fullName" /><s:if test="!#userStatus.last">,</s:if>
                    </s:iterator>
                </td>
            </tr>
        </s:iterator>

  The next example iterates over a an action collection and passes every iterator value to another action. The trick here lies in the use of the '[0]' operator. It takes the current iterator value and passes it on to the edit action. Using the '[0]' operator has the same effect as using <s:property />. (The latter, however, does not work from inside the param tag).

            <s:action name="entries" var="entries"/>
            <s:iterator value="#entries.entries" >
                <s:property value="name" />
                <s:property />
                <s:push value="...">
                    <s:action name="edit" var="edit" >
                        <s:param name="entry" value="[0]" />
                    </s:action>
                </push>
            </s:iterator>

  A loop that iterates 5 times

       <s:iterator var="counter" begin="1" end="5" >
          <!-- current iteration value (1, ... 5) -->
          <s:property value="top" />
       </s:iterator>

  Another way to create a simple loop, similar to JSTL's <c:forEach begin="..." end="..." ...> is to use some OGNL magic, which provides some under-the-covers magic to make 0-n loops trivial. This example also loops five times.

       <s:iterator status="stat" value="(5).{ #this }" >
          <s:property value="#stat.count" /> <!-- Note that "count" is 1-based, "index" is 0-based. -->
       </s:iterator>

  A loop that iterates over a partial list

       <s:iterator value="{1,2,3,4,5}" begin="2" end="4" >
          <!-- current iteration value (2,3,4) -->
          <s:property value="top" />
       </s:iterator>

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected Integer` | `begin`
    `protected String` | `beginStr`
    `protected Integer` | `end`
    `protected String` | `endStr`
    `protected Iterator` | `iterator`
    `protected Object` | `oldStatus`
    `protected IteratorStatus` | `status`
    `protected String` | `statusAttr`
    `protected IteratorStatus.StatusState` | `statusState`
    `protected Integer` | `step`
    `protected String` | `stepStr`
    `protected String` | `value`

    - ### Fields inherited from class org.apache.struts2.components.ContextBean

      `var`

    - ### Fields inherited from class org.apache.struts2.components.Component

      `actionMapper, COMPONENT_STACK, devMode, escapeHtmlBody, parameters, performClearTagStateForTagPoolingServers, stack, standardAttributesMap, throwExceptionOnELFailure`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `IteratorComponent(ValueStack stack)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `end(Writer writer, String body)` Callback for the end tag of this component.
    `void` | `setBegin(String begin)`
    `void` | `setEnd(String end)`
    `void` | `setStatus(String status)`
    `void` | `setStep(String step)`
    `void` | `setValue(String value)`
    `boolean` | `start(Writer writer)` Callback for the start tag of this component.

    - ### Methods inherited from class org.apache.struts2.components.ContextBean

      `getVar, putInContext, setVar`

    - ### Methods inherited from class org.apache.struts2.components.Component

      `addAllParameters, addParameter, completeExpression, copyParams, determineActionURL, determineNamespace, end, escapeHtmlBody, fieldError, findAncestor, findString, findString, findValue, findValue, findValue, getComponentStack, getParameters, getPerformClearTagStateForTagPoolingServers, getStack, getStandardAttributes, isAcceptableExpression, isValidTagAttribute, popComponentStack, setActionMapper, setDevMode, setEscapeHtmlBody, setNotExcludedAcceptedPatterns, setPerformClearTagStateForTagPoolingServers, setThrowExceptionsOnELFailure, setUrlHelper, stripExpression, toString, usesBody`

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### iterator

          protected Iterator iterator

    - #### status

          protected IteratorStatus status

    - #### oldStatus

          protected Object oldStatus

    - #### statusState

          protected IteratorStatus.StatusState statusState

    - #### statusAttr

          protected String statusAttr

    - #### value

          protected String value

    - #### beginStr

          protected String beginStr

    - #### begin

          protected Integer begin

    - #### endStr

          protected String endStr

    - #### end

          protected Integer end

    - #### stepStr

          protected String stepStr

    - #### step

          protected Integer step

  - ### Constructor Detail

    - #### IteratorComponent

          public IteratorComponent(ValueStack stack)

  - ### Method Detail

    - #### start

          public boolean start(Writer writer)

      Description copied from class: `Component`
      Callback for the start tag of this component. Should the body be evaluated?
      Overrides:
        `start` in class `Component`
      Parameters:
        `writer` - the output writer.
      Returns:
        true if the body should be evaluated

    - #### end

          public boolean end(Writer writer,
                             String body)

      Description copied from class: `Component`
      Callback for the end tag of this component. Should the body be evaluated again?
      NOTE: will pop component stack.
      Overrides:
        `end` in class `Component`
      Parameters:
        `writer` - the output writer.
        `body` - the rendered body.
      Returns:
        true if the body should be evaluated again

    - #### setStatus

          public void setStatus(String status)

    - #### setValue

          public void setValue(String value)

    - #### setBegin

          public void setBegin(String begin)

    - #### setEnd

          public void setEnd(String end)

    - #### setStep

          public void setStep(String step)

Copyright © 2000–2023 Apache Software Foundation. All rights reserved.