Not getting selected value from Dropdown in primefaces backing bean - jsf-2

Question

Hi I have built two consecutive dropdowns one being initialized in init() method and the other being populated on the basis on first one's selection.
Command Button is used to use both the selected values for processing, Strange that Setter for the selected values is being called twice(setting blank the second time..as I found out in debugging)..I need understand whyu I am getting blank values?
myPage.xhtml
<p:selectOneMenu id="dbList"
value="#{backingBean.selectedConnection}"
style="width:200px">
<p:ajax listener="#{backingBean.onConnectionChange()}"
update="aliasList" />
<f:selectItem itemLabel="Select" itemValue="#{backingBean.selectedConnection}"
noSelectionOption="false" />
<f:selectItems value="#{backingBean.connectionsTypeList}" />
</p:selectOneMenu>
<p:outputLabel for="aliasList" value="Connection Alias" />
<p:selectOneMenu id="aliasList"
value="#{backingBean.aliasSelected}" style="width:200px">
<f:selectItem itemLabel="Select" itemValue="#{backingBean.aliasSelected}"
noSelectionOption="false"/>
<f:selectItems value="#{backingBean.connectionsList}" />
</p:selectOneMenu>
<p:commandButton value="myButton"
actionListener="#{backingBean.myMethod()}"
id="myButton" />
backingBean.java
#ManagedBean
#ViewScoped
public class BackingBean implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
private ArrayList<String> connectionsList;
private String aliasSelected;
private String selectedConnection;
private ArrayList<String> connectionsTypeList;
#PostConstruct
public void init() {
// Initialize the connection alias drop down here
this.connectionsTypeList = getConnectionTypeList();
this.connectionsList=new ArrayList<String>();
}
public void onConnectionChange() {
System.out.println("In Connection Change, populating aliases");
getConnectionDBList();
}
public String getAliasSelected() {
return aliasSelected;
}
//Dont know why this is called twice on button click and second time value set is blank
public void setAliasSelected(String aliasSelected) {
this.aliasSelected = aliasSelected;
}
public ArrayList<String> getConnectionsList() {
return connectionsList;
}
public void setConnectionsList(ArrayList<String> connectionsList) {
this.connectionsList = connectionsList;
}
public String getSelectedConnection() {
return selectedConnection;
}
public void setSelectedConnection(String selectedConnection) {
this.selectedConnection = selectedConnection;
}
public ArrayList<String> getConnectionsTypeList() {
return connectionsTypeList;
}
public void setConnectionsTypeList(ArrayList<String> connectionsTypeList) {
this.connectionsTypeList = connectionsTypeList;
}
public void myMethod() {
System.out.println("selected Alias is "+aliasSelected);
System.out.println("selected connection is "+selectedConnection);
}
}
New to primefaces,please help

Answer 1

Answer to this :"setting blank the second time..as I found out in debugging"
This is happening because I realized I was pointing the same property to two ui components..as in..two dropdowns in the same page were linked to the same property of the backing bean..Sillyh Mistake..hence the second call to the setter..with Blank values..as it was not initialized for the second UI Component