问题描述
我正在尝试使下拉菜单动态化,以下是我得到的代码和异常.请帮帮我
I am trying to make my dropdown dynamic and below is the code and exception i am getting. Please help me out
bean:
private String dropDownValue;
List<SelectItem> testDropDown = new ArrayList<SelectItem>();
List<SelectItem> testDropDownTwo = new ArrayList<SelectItem>();
public String getDropDownValue() {
return dropDownValue;
}
public void setDropDownValue(String dropDownValue) {
this.dropDownValue = dropDownValue;
}
public List<SelectItem> getTestDropDown() {
testDropDown.add(new SelectItem("One"));
testDropDown.add(new SelectItem("Two"));
testDropDown.add(new SelectItem("Three"));
testDropDown.add(new SelectItem("Four"));
return testDropDown;
}
XHtml代码:
<h:selectOneMenu value="#{loginBean.dropDownValue}">
<f:selectItem value="#{loginBean.testDropDown}" />
</h:selectOneMenu>
例外:
例外
javax.servlet.ServletException: java.util.ArrayList cannot be cast to javax.faces.model.SelectItem
javax.faces.webapp.FacesServlet.service(FacesServlet.java:321)
root cause
java.lang.ClassCastException: java.util.ArrayList cannot be cast to javax.faces.model.SelectItem
com.sun.faces.renderkit.SelectItemsIterator.initializeItems(SelectItemsIterator.java:185) com.sun.faces.renderkit.SelectItemsIterator.hasNext(SelectItemsIterator.java:131)
com.sun.faces.renderkit.html_basic.MenuRenderer.renderOptions(MenuRenderer.java:758)
com.sun.faces.renderkit.html_basic.MenuRenderer.renderSelect(MenuRenderer.java:840)
com.sun.faces.renderkit.html_basic.MenuRenderer.encodeEnd(MenuRenderer.java:294)
javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:879)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:1650)
某些类广播异常正在发生.但是我正在将SelectItem的ArrayList发送到列表中
Some classcast exception is happening. but i am sending the ArrayList of SelectItem to the list
如果我将selectItem标记中的Value属性更改为itemValue,则不会引发异常,但不会获得任何值,我会获得对象名称,如在单个列表中的下拉列表中一样
if i change the Value attribute in selectItem tag to itemValue it is not trowing a exception but i am not getting any value i am getting the object names as in the drop down in a single list
推荐答案
您必须使用f:selectItems
:
<h:selectOneMenu value="#{loginBean.dropDownValue}">
<f:selectItems value="#{loginBean.testDropDown}"/>
</h:selectOneMenu>
f:selectItem
用于在菜单中添加单个SelectItem
,要添加SelectItems
的整个List
,则必须使用此标记.
f:selectItem
is used to add a single SelectItem
to the menu, to add a whole List
of SelectItems
you have to use this tag.
这篇关于java.lang.ClassCastException:无法将java.util.ArrayList强制转换为javax.faces.model.SelectItem的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!