String objType='Contact';
Map<String, Schema.SObjectType> schemaMap = Schema.getGlobalDescribe();
Schema.SObjectType leadSchema = schemaMap.get(objType);
Map<String, Schema.SObjectField> fieldMap = leadSchema.getDescribe().fields.getMap();
List<String> shagni = new List<String>();

for (String fieldName: fieldMap.keySet()) {
  Schema.DisplayType fielddataType = fieldMap.get(fieldName).getDescribe().getType();
  System.debug(fielddataType);
}