Struts iterators (iterator) traverse List of 4 common examples

1. Traverse list<string>

2. Traverse list<list<string>>

3. Traverse Userentity

4. Traverse list<userentity>

For the detailed code of the example, please refer to Annex 1 for a screenshot of two 4 examples (see Figure 1 below):

Figure 1:4 Examples of traversing a listd run result
keywords: struts tags, iterator iterators,list<string>,list<list<string>>

1. Traverse list<string>

(1) Backstage Testaction.java part code:

         TODO gives the list assignment
         if (list==null) {
             list=new arraylist<string> ();
             List.add ("Liu Bei");
             List.add ("Guan Yu");
          List.add ("Zhang Fei");
            List.add ("Zhao Yun");
         }

(2) Front desk jsp+s tag part source code:

                      <%--List<String> Traverse--%> <table width= "242" height= "" border= "
                              1 "cellpadding=" 1 "cellspacing=" 1 "> <caption>
                              LIST&AMP;LTSTRING&AMP;GT Traversal </caption> <tr>
                               <%--Description: <s:iterator id= "Alias" value= "background list variable name" > <s:if test= "#别名!=null" >--%> <s : iterator id= "li" value= "list" > <td> <s:
                                     If test= "#li!=null" > <s:property/>
                         </s:if> </td> </s:iterator>
</tr>                     </table> <s:iterator value= "STRs" >   

<s:property/><br> </s:iterator> or: <s:iterator value= "STRs" var= "var" > <s:propertyvalue= "Var"/><br> </s:iterator>

Note: Traverse the list<string> run result reference above Figure 1 (upper left)

2. Traverse list<list<string>>

(1) Backstage Testaction.java part code:

//TODO assigns a value to listlist (two-dimensional list) if (listlist==null) {listlist=new arraylist<list& Lt
              String>> ();
              List<string> li=new arraylist<string> ();
              Li.add ("name");
              Li.add ("forces");
              Li.add ("title");
              Listlist.add (LI); 
             /*list is a reference type (one-dimensional list object is saved as an address), adding a different list to a two-dimensional listing needs to be instantiated */Li=new arraylist<string> ();
             Li.add ("Liu Bei");
             Li.add ("Shu");
             Li.add ("eldest brother");
             Listlist.add (LI);
             Li=new arraylist<string> ();
             Li.add ("Guan Yu");
             Li.add ("Shu");
             Li.add ("Old 2"); Listlist.add (LI); 

             Li=new arraylist<string> ();
             Li.add ("Zhang Fei");
             Li.add ("Shu");
             Li.add ("Old 3");
             Listlist.add (LI);
             Li=new arraylist<string> ();
             Li.add ("Zhao Yun");
             Li.add ("Shu");
             Li.add ("Generals");
             Listlist.add (LI);

(2) Front desk jsp+s tag part source code:

     <%--List<List<String>> Traverse--%>
                     <table width= "242" height= "1" border= "1"
                         cellspacing= "1" >
                         <caption>
                             list&ltlist&ltstring&gt&gt traverse as follows:
                         </ caption>
                         <s:iterator value= "#request. Listlist" status= "st" >
                             <tr>
                                 <s:iterator value= "#request. Listlist.get (#st. Index)" >
                                     <td valign= "Middle" align= "center" >
                                         <s:property/>
                                     </td>
                                 </s:iterator>
                             </tr>
                         </s:iterator>
                     </table>

Note: Traverse the list<list<string>> run result reference above Figure 1 (upper right)

3. Traverse userentity

(1) Backstage Testaction.java part code:

TODO gives userentity assignment
  if (userentity==null) {
      userentity=new userentity ("Zhuge Liang", "male", PNS);
  }

(2) Front desk jsp+s tag part source code:

<%--userentity traversal is as follows:--%> < table width = "242" height = "" border = "1" cellpadding = "1" cellspacing = "1" > < caption > userentity traversal as follows: </caption > < tr > <%--< td >< S:property value = "#变量名. Property name "/></TD >--%> < td > < S:property value =" Userentity.name "/> </td > < td > < S:property value = "Userentity.sex"/> </td > < td > < S:property value = "Userentity.age"/> </TD > </tr > </table >

Note: Traverse the userentity run result reference above Figure 1 (bottom left)

4. Traverse list<userentity>

(1) Backstage Testaction.java part code:

  TODO assigns the list<userentity> to the
      if (users==null) {
          users=new arraylist<userentity> ();
          Userentity user=new userentity ("Zhang Fei", "male",);
          Users.add (user);
          User=new userentity ("Reese", "male", +);
          Users.add (user);
          User=new userentity ("Wang Wu", "male",);
          Users.add (user);
          User=new userentity ("Little Joe", "female", +);
          Users.add (user);
     }

View Code

(2) Front desk jsp+s tag part source code:

  <%--list<userentity> traverse the following:--%> <table width= "242" height= "1" border= "Cellpaddi"
                              ng= "1" cellspacing= "1" > <caption>
                              The LIST&AMP;LTUSERENTITY&AMP;GT traversal is as follows: </caption> <tr>
                             <th> name </th>
                             <th> Sex </th>
                         <th> Age </th>
         </tr> <s:iterator id= "U" value= "Users" > <%--
         <s:iterator id= "Name" Value= "collection to Traverse" > Users: list<userentity> users corresponding to the background action class;
                     --%>        <tr> <%--<td><s:property value= "#別名. Entity class Property name"/></td>--% 
                                 > <td> <s:property value= "#u. Name"/>
                                     </td> <td> <s:property value= "#u. Sex"/> </td> &lt ;td> <s:property value= "#u. Age"/> </td&
                             Gt </tr> </s:iterator> </table>

Note: Traverse the list<userentity> run result reference above Figure 1 (bottom right)

5. Comparison of usage

(1) Compare list<string> and Userentity

They traverse the display similarly, but careful friends will find that they have the following main differences:
Difference 1: List<string> traversal requires a iterator iterator such as <s:iterator id= "alias" value= "background list variable name", and does not need the Value property directly with the <s:property/ > get list elements;
Difference 2: Userentity on the contrary, iterator iterators are not required, but the Value property <s:property value= "#变量名. Property name"/> is required to get the list element.

(2) Compare list<list<string>> and list<userentity>

They also have similar traversal displays, and they have the following differences:
Difference 1: List<list<string>> because the list does not have attributes that require the use of the iterator's properties status= "St",
such as:<