Find and replace text - apex trigger or button

Question

I have an issue where by I need a temporary fix, I am trying to create a method of looking at a string of text on the opportunity and replacing all the $ with £ (custom text field)

A trigger example I found is

trigger YourTrigger on Solution (before update) { 
  for(Solution s : trigger.new) {
    s.replaceAll('Hello World','Goodbye World');
  }
}

but if possible I would rather have a button on the opportunity that could provide this functionality. I also need to limit this trigger to fire only on opptys that match a pre specified field criteria eg checkbox__c = true

Best Answer

Why would you need to this with a Trigger? You could do this with a Workflow Rule+ Field Update. Something like this:

1. Setup | Create | Workflows & Approvals | Workflow Rules
2. New Rule
3. Select the Object: Opportunity
4. Evaluation Criteria: created and every time it’s edited [2nd Option]
5. Rule Criteria: formula evluates to true
6. Formula: 

   AND(
     Checkbox_Field__c = TRUE,
     NOT(ISBLANK(Text_Field__c)),
     FIND('$', Text_Field__c) >= 1, 
     OR(
       ISNEW(), 
       ISCHANGED(Text_Field__c),
       ISCHANGED(Checkbox_Field__c)
     )
   )

7. Click Save & Next
8. From under Immediate Workflow Actions, click Add Workflow Action to select Field Update
9. Select the Field to Update: Opportunity: Text Field
10. Select Use a Formula to Set the New Value
11. Formula: 

    SUBSTITUTE(Text_Field__c, '$', '£')

12. Click Save
13. Click Done
14. Click Activate

So this one runs whenever some changes the value on the Text Field or the Checkbox/when a new record is created but provided that it has some value and not is EMPTY, the Checkbox is checked(aka TRUE), the Text Field has at least one Dollar sign($).