a4j:actionparam in java

[oni_ffm]

hello,
i have tried to create a4j:commandButton and a4j:actionparam in java. For example i use ActionParameter Demo

<a4j:commandButton value="Set Name to Alex" reRender="rep" >
 <a4j:actionparam name="username" value="Alex" assignTo="#{userBean.name}"/>
</a4j:commandButton>

hier is my code

HtmlAjaxCommandButton() button = new HtmlAjaxCommandButton();
button.setTitle("Set Name to Alex");

HtmlActionParameter actionParameter = new HtmlActionParameter();
actionParameter.setName("username");
actionParameter.setValue("John");
button.getChildren().add(actionParameter);

but i don't know how can i define reRender="rep" and assignTo="#{userBean.name}"

has someone idee?
thanks in advance

[ilya_shaikovsky]

setRerender method for command Button
and setAssignToBinding for parameter (ValueExpression should be passed)

[oni_ffm]

hello,
i did what you said

button = new HtmlAjaxCommandButton();
button.setValue("Set Name to Alex");
button.setReRender("rep");

HtmlActionParameter actionParameter = new HtmlActionParameter();
actionParameter.setName("username");
actionParameter.setValue("Alex");
actionParameter.setAssignToBinding(createValueExpression("#userBean.name}", String.class)) ;
button.getChildren().add(actionParameter);

but at first, button label is not "Set Name to Alex" but org.ajax4jsf.......
second when i click on button, this name will be not changed

ilya_shaikovsky can you give more concrete explain please

thanks a lot