Error class is part of SaveResult, which is generated when a user attempts to save a Salesforce record.
The following are methods for Error. All are instance methods.
public String[] getFields()
Type: String[]
public StatusCode getStatusCode()
Type: StatusCode
The full list of status codes is available in the WSDL file for your organization (see Downloading Salesforce WSDLs and Client Authentication Certificates in the Salesforce online help.)