How to do Impact analysis to salesforce projects?

Hi
I have a text field. and the user entered an email address. I want to find out the email address which are in text fields?
please let me know if anybody know how to write the apex code. If anybody having the code. please send to me. that will be helpfull us.

Thanks
Seshu

Hi,
I have dropdown and having some values etc, USA, INDIA, UK. If I selected USA, The USA text field whould be visible. If I selected UK, the UK text field should be visible. This is my requirement.
How can I achieve this? please help me.

Hi
I have a Custom Object, Content Object and ContentDocumet object. Custom Object is patent and content objects are child. 
My requirement is, In the custom object if the flag is True then conectDocument need to Transfer to Custom object. If the flag is flase then the contentDocument should be InActive.
Each custom Object have associate content Document record.
Please tell me how can we write a trigger? We have to write the trigger on custom object.

Question:- An Email notification should be sent to Inbox when Active = True, and Expiration Date is one week from current date.
Please help me how to write batch apex class for the above requirement?

Hi
I have Active__C field and Expiration_Date__c field. If the active__c Flag is true, then the Expiration_Date__c must be greaterthan current date. 
I need to write Batch apex class for this requirement.This Batch apex class runs on thousands of records.
Please help me any one know how to write code for this.

Thanks
Babu