Select box in struts2

Whenever you start working in struts2 tag select box so might be get the following error but you might be helpless to solve following error.

 ERROR [[jsp]] Servlet.service() for servlet jsp threw exception tag 'select', field 'list', name 'listShowName': The requested list key 'listForShow' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]

Today i will give you the detail description about the select box.

There may be the following criteria to display record in select box in real application world.

1. Show ArrayList data in select box
2. Show Map data in select box
3. Show Java Beans in select box

I will go step by step so you can get better idea to use it.

1. Show ArrayList Data in Select Box :

a). You have to create an ArrayList Object in your STRUTS Action java class and create its getter/setter method.

public class MySelectBox extends ActionSupport {

    private List<String> valueForSelect;

    public List<String> getValueForSelect() {

        return valueForSelect;

    }

    public void setValueForSelect(List<String> valueForSelect) {

        this.valueForSelect = valueForSelect;

    }

}

b). Now you have to fill the arrayList Object in your action calling method.

public String selectMethod() {

    valueForSelect = new ArrayList<String>();

    valueForSelect.add("Value 1");

    valueForSelect.add("Value 2");

    valueForSelect.add("Value 3");

    valueForSelect.add("Value 4");

    valueForSelect.add("Value 5");

    valueForSelect.add("Value 6");

    valueForSelect.add("Value 7");

    return SUCCESS;

}

 c). Now use the select box tags in your jsp page.

<s:select label="Select Day" name="usingArrayList"  headerKey="1"  headerValue="-- Please Select --"  list="valueForSelect" theme="simple" />

2. Show Map data in select box

a). You have to create an Map Object in your STRUTS Action java class and create its getter/setter method.

 public class MySelectBox extends ActionSupport {

    private Map<Integer, String> mapForSelect;

    public Map<Integer, String> getMapForSelect() {

        return mapForSelect;

    }

    public void setMapForSelect(Map<Integer, String> mapForSelect) {

        this.mapForSelect = mapForSelect;

    }

}

b). Now you have to fill the Map Object in your action calling method.

public String selectMethod() {

    mapForSelect = new HashMap<Integer, String>();

    mapForSelect.put(1, "map 1");

    mapForSelect.put(2, "map 2");

    mapForSelect.put(3, "map 3");

    mapForSelect.put(4, "map 4");

    mapForSelect.put(5, "map 5");

    mapForSelect.put(6, "map 6");

    return SUCCESS;

}

c). Now use the select box tags in your jsp page.
 

<s:select label="Select Day" name="usingMap" list="mapForSelect" theme="simple" headerKey="1"  headerValue="-- Please Select --"/>

3. Show Java Beans in select box

a) First you have to create a java bean class .

package com.example.actions;

 

public class SelectBean {

 

    private Integer id;

    private String username;

    private String password;

 

    public Integer getId() {

        return id;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    public String getUsername() {

        return username;

    }

    public void setUsername(String username) {

        this.username = username;

    }

    public String getPassword() {

        return password;

    }

    public void setPassword(String password) {

        this.password = password;

    }

} 

 

b). You have to create an JavaBean Object in your STRUTS Action java class and create its getter/setter method.

public class MySelectBox extends ActionSupport {

    private List<SelectBean> listForShow = new ArrayList<SelectBean>();

 

    public List<SelectBean> getListForShow() {

        return listForShow;

    }

    public void setListForShow(List<SelectBean> listForShow) {

        this.listForShow = listForShow;

    }

}

 

c). Now you have to fill the JavaBean Object in your action calling method.

public String selectMethod() {

SelectBean selectBean1 = new SelectBean();

selectBean1.setId(2);

selectBean1.setUsername("aoi blog2");

selectBean1.setPassword("jigar nagar");

 

SelectBean selectBean2 = new SelectBean();

selectBean2.setId(3);

selectBean2.setUsername("aoi blog3");

selectBean2.setPassword("jigar nagar");

 

listForShow.add(selectBean);

listForShow.add(selectBean1);

listForShow.add(selectBean2);

return SUCCESS;

}

d). Now use the select box tags in your jsp page.

<s:select list="listForShow" listKey="id" listValue="username" name="usingJavaBean"  theme="simple" headerKey="1"  headerValue="-- Please Select --"/>

Now we will add the submit button that will show you the selected items from the select box.
a) Added Save method in struts Action.

public class MySelectBox extends ActionSupport {

private String usingArrayList;

private String usingMap;

private String usingJavaBean;

 

public String getUsingArrayList() {

return usingArrayList;

}

 

public void setUsingArrayList(String usingArrayList) {

    this.usingArrayList = usingArrayList;

}

 

public String getUsingMap() {

    return usingMap;

}

 

public void setUsingMap(String usingMap) {

    this.usingMap = usingMap;

}

 

public String getUsingJavaBean() {

    return usingJavaBean;

}

 

public void setUsingJavaBean(String usingJavaBean) {

    this.usingJavaBean = usingJavaBean;

}

 

public String saveMethod() {

    System.out.println("usingArrayList "+usingArrayList);

    System.out.println("usingJavaBean "+usingJavaBean);

    System.out.println("usingMap "+usingMap);

    selectMethod();

    return SUCCESS;

}

 b) added the following below code at your jsp page.

<s:property value="usingArrayList"/><br/>

<s:property value="usingMap"/><br/>

<s:property value="usingJavaBean"/>

 

Please Note : select box name and define property name is action class should be same.
Now we are just mixing all code

Struts2.xml file :

 <!DOCTYPE struts PUBLIC

"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"

"http://struts.apache.org/dtds/struts-2.0.dtd">

 

<struts>

    <constant name="struts.devMode" value="true" />

    <package name="struts2" extends="struts-default" namespace="/">

        <action name="listForSelect" class="com.example.actions.MySelectBox" method="selectMethod">

            <result name="success">/select.jsp</result>

        </action>

        <action name="saveSelect" class="com.example.actions.MySelectBox" method="saveMethod">

            <result name="success">/select.jsp</result>

        </action>

    </package>

</struts>

Java Action Class :

package com.example.actions;

 

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

 

import com.opensymphony.xwork2.ActionSupport;

 

public class MySelectBox extends ActionSupport {

    private List<String> valueForSelect;

    private Map<Integer, String> mapForSelect;

    private List<SelectBean> listForShow = new ArrayList<SelectBean>();

 

    private String usingArrayList;

    private String usingMap;

    private String usingJavaBean;

 

    public String selectMethod() {

        System.out.println("Hello I m calling");

        valueForSelect = new ArrayList<String>();

        valueForSelect.add("Value 1");

        valueForSelect.add("Value 2");

        valueForSelect.add("Value 3");

        valueForSelect.add("Value 4");

        valueForSelect.add("Value 5");

        valueForSelect.add("Value 6");

        valueForSelect.add("Value 7");

 

        mapForSelect = new HashMap<Integer, String>();

        mapForSelect.put(1, "map 1");

        mapForSelect.put(2, "map 2");

        mapForSelect.put(3, "map 3");

        mapForSelect.put(4, "map 4");

        mapForSelect.put(5, "map 5");

        mapForSelect.put(6, "map 6");

 

        SelectBean selectBean = new SelectBean();

        selectBean.setId(1);

        selectBean.setUsername("aoi blog1");

        selectBean.setPassword("jigar nagar");

 

        SelectBean selectBean1 = new SelectBean();

        selectBean1.setId(2);

        selectBean1.setUsername("aoi blog2");

        selectBean1.setPassword("jigar nagar");

 

        SelectBean selectBean2 = new SelectBean();

        selectBean2.setId(3);

        selectBean2.setUsername("aoi blog3");

        selectBean2.setPassword("jigar nagar");

 

        listForShow.add(selectBean);

        listForShow.add(selectBean1);

        listForShow.add(selectBean2);

 

        return SUCCESS;

    }

    public String getUsingArrayList() {

        return usingArrayList;

    }

    public void setUsingArrayList(String usingArrayList) {

        this.usingArrayList = usingArrayList;

    }

    public String getUsingMap() {

        return usingMap;

    }

    public void setUsingMap(String usingMap) {

        this.usingMap = usingMap;

    }

    public String getUsingJavaBean() {

        return usingJavaBean;

    }

    public void setUsingJavaBean(String usingJavaBean) {

        this.usingJavaBean = usingJavaBean;

    }

    public String saveMethod() {

        System.out.println("usingArrayList "+usingArrayList);

        System.out.println("usingJavaBean "+usingJavaBean);

        System.out.println("usingMap "+usingMap);

        selectMethod();

        return SUCCESS;

    }

    public List<SelectBean> getListForShow() {

        return listForShow;

    }

    public void setListForShow(List<SelectBean> listForShow) {

        this.listForShow = listForShow;

    }

    public List<String> getValueForSelect() {

        return valueForSelect;

    }

    public void setValueForSelect(List<String> valueForSelect) {

        this.valueForSelect = valueForSelect;

    }

    public Map<Integer, String> getMapForSelect() {

        return mapForSelect;

    }

    public void setMapForSelect(Map<Integer, String> mapForSelect) {

        this.mapForSelect = mapForSelect;

    }

 

}

 Java Bean Class:

package com.example.actions;

 

public class SelectBean {

 

    private Integer id;

    private String username;

    private String password;

 

    public Integer getId() {

        return id;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    public String getUsername() {

        return username;

    }

    public void setUsername(String username) {

        this.username = username;

    }

    public String getPassword() {

        return password;

    }

    public void setPassword(String password) {

        this.password = password;

    }

}

Your JSP Page

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>

<%@taglib prefix="s" uri="/struts-tags" %>

 

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head><title>Select Box Example - AOI Blogs</title></head>

  <body>

    <center>

        <h1>Select Box Example</h1>

    </center>

    <s:form action="saveSelect" method="post" namespace="/">

    <table cellpadding="2" cellspacing="2" border="1" align="center">

    <tr>

        <td>Using Array List</td>

        <td><s:select label="Select Day" name="usingArrayList"  headerKey="1"  headerValue="-- Please Select --"  list="valueForSelect" theme="simple" /></td>

    </tr>

    <tr>

        <td>Using Map</td>

        <td><s:select label="Select Day" name="usingMap" list="mapForSelect" theme="simple" headerKey="1"  headerValue="-- Please Select --"/></td>

    </tr>

    <tr>

        <td>Using Java Beans</td>

        <td><s:select list="listForShow" listKey="id" listValue="username" name="usingJavaBean"  theme="simple" headerKey="1"  headerValue="-- Please Select --"/> </td>

    </tr>

    <tr>

        <td colspan="2" align="center">

            <s:submit value="SUBMIT" theme="simple"></s:submit>

        </td>

    </tr>

    </table>

    </s:form>

    <s:property value="usingArrayList"/><br/>

    <s:property value="usingMap"/><br/>

    <s:property value="usingJavaBean"/>

  </body>

</html>

 Thank you so much to reading this article. If you have any query so feel free to ask.