Generic way to update Record Type with a trigger based on a passed value

Get the recordType ID based on the arguments Object Name and the Recordtype name.

 /**  
   * getRecordTypeId  
   * Author: Hasantha Liyanage  
   * Created: 2014-12-01  
   * Arguments: sobjectName: the name of the object we want to get the record type for;  
   *      recordTypeName: the name of the record type we want to fetch  
   * Returns:  If found returns the id of the record type, if not returns null. This  
   *       method retrives recordtypes with using metadata.  
    **/  
   public static Id getRecordTypeId(String sobjectName, String recordTypeName) {  
     Map<String, Schema.SObjectType> sObjectMap = Schema.getGlobalDescribe();  
     // getting Sobject Type  
     Schema.SObjectType s = sObjectMap.get(sobjectName);  
     Schema.DescribeSObjectResult resSchema = s.getDescribe();  
     //getting all Recordtype for the Sobject  
     Map<String,Schema.RecordTypeInfo> recordTypeInfo = resSchema.getRecordTypeInfosByName();  
     //particular RecordId by Name  
     return recordTypeInfo.get(recordTypeName).getRecordTypeId();  
   }  

 

 /**  
   * setCustomRecordType  
   * Author: Hasantha Liyanage  
   * Created: 2014-12-01  
   * Arguments: Object type name, dummy picklist field name, List of objects which the trigger returns as Trigger.new  
   * Returns:  void/ updates the recordtypes  
    **/  
   public static void setCustomRecordType(String typeName, String fieldName, List<sObject> objectsList) {  
     // iterate through object list  
     for (sObject obj: objectsList) {  
       String selectedValue = String.valueOf(obj.get(fieldName));  
       // update the recordtype with picklist selected value  
       Id oid = getRecordTypeId(typeName,selectedValue);  
       obj.put('RecordTypeId',oid);   
     }  
   }  

--