Does the sink parameter of the decode() method and the return value have to be instances of the same class?

Here's the decode() method definition in the com.oss.asn1.Coder class:

public final AbstractData decode(java.io.InputStream source, 
                AbstractData sink) 
                throws DecodeNotSupportedException, 
                DecodeFailedException

If the sink is not null then it should be an instance of a class which represents the PDU whose encoding is expected to be present in the source stream. It is possible to pass null as the sink argument if the coder supports the PDU detection feature. If the sink is null and PDU detection is available then the actual PDU in the source will be determined from its tag.

Here is an example:

if (coder.isPDUDetectionAvailable()) 
value = coder.decode(mySource, null) 
else 
value = coder.decode(mySource, new MyRec()); 

PDU detection is supported by BER and DER coders if the ASN.1 spec uses distinct tags for all the PDUs in the spec. PDU detection is not available for PER and UPER coders.

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