I changed an array to a list, so I want to change all instances of myObject[index] to myObject.get(index) where index is different integers. I can          
        
Use the following regex replacement:
Find: myObject\[(.*?)\]
Replace: myObject.get($1)
If the index is an integer, you may replace (.*?) with (\d+).
The pair of unescaped parentheses creates a capturing group that we may reference from the replacement pattern using $ + Group ID. $1 will insert the index into the replacement result.