Hello,

I have some experience in APEX and Visualforce, but still found issues on developing.

Could someone please give me an advice, how to overwrite the close date on Opportunities?

I have generated a new field on Opportunity, called NewDate__c (Date, Label: "New Close Date"). and a save-button on my ExtensionController.

everytime, when I access the NewDate__c in the method {!overridenewdatetoclosedate}, I receive this exeption:

Attempt to de-reference a null object
An unexpected error has occurred. Your development organization has been notified. 

my VF-PAge is this:

<apex:page standardController="Opportunity"
	extensions="ClsOppChangeCloseDate" action="{!init}">
	<apex:form id="FormChangeCloseDate1">
		<apex:pageBlock mode="inlineEdit" id="pb">
			<apex:pageBlockSection id="pbs1">
				<apex:commandButton action="{!overridenewdatetoclosedate}"
					value="Save all" id="btnSave" />
			</apex:pageBlockSection>
			<apex:pageBlockSection id="pbs2">
				<apex:outputField value="{!opportunity.closeDate}" />
				<apex:outputField value="{!opportunity.NewDate__c}" />
			</apex:pageBlockSection>
			<apex:pageBlockSection id="pbs3">
				<apex:outputText value="{!oldDate}" />
				<apex:outputText value="{!newDate}" />
			</apex:pageBlockSection>
		</apex:pageBlock>
	</apex:form>
</apex:page>

my ExtensionController is this:

public class ClsOppChangeCloseDate {
	private ApexPages.StandardController stdCtrl;

	public Datetime oldDate {get; set;}
	public Datetime newDate  {get; set;}
	public Integer difDate {get; set;}

	public Opportunity chOpp {get; set;}

	public ClsOppChangeCloseDate(ApexPages.StandardController std){
		stdCtrl=std;
	}

	public void init(){
		Opportunity chOpp = [SELECT Id, Name, CloseDate, NewDate__c FROM Opportunity WHERE Id = :stdCtrl.getId()];
		oldDate = chOpp.CloseDate;
		newDate = chOpp.NewDate__c;
	} // end init();

	public PageReference overridenewdatetoclosedate(){
	newDate = chOpp.NewDate__c;
	stdCtrl.save();
	return null;
	}

	public PageReference save() {
		stdCtrl.save();
		return null;
	}
}

any hints are welcome!