Change case status only though Visualforce page

Hi Nitish,

Try this code:-
public class CaseControl {
public static Boolean allowReopen = false;

public static void verifyReopen(Case[] prior, Case[] current) {
if(!allowReopen) {
for(Integer index = 0, size = current.size(); index < size; index++) {
if(prior[index].Status == 'Closed' &&
current[index].Status <> 'Closed') {
current[index].addError('Please use the Visualforce page to reopen this case.');
}
}
}
}
}

Trigger:-
trigger verifyReopen on Case (after update) {
CaseControl.verifyReopen(Trigger.old, Trigger.new);
}

Case Reopen:-
public PageReference reopenAndSave() {
CaseControl.allowReopen = true;
caseRecord.Status = 'Reopened';
update caseRecord;
return new ApexPages.StandardController(caseRecord).view();
}