Converting a Java byte reader to an InputStream -

consider generic byte reader implementing following simple api read unspecified number of bytes data structure otherwise inaccessible:

public interface bytereader {     public byte[] read() throws ioexception; // returns null @ eof } 

how above efficiently converted standard java inputstream, application using methods defined inputstream class, works expected?

a simple solution subclassing inputstream to

1. call read() method of bytereader as needed read(...) methods of inputstream
2. buffer bytes retrieved in byte[] array
3. return part of byte array expected, e.g., 1 byte @ time whenever inputstream read() method called.

however, requires more work efficient (e.g., avoiding multiple byte array allocations). also, application scale large input sizes, reading memory , processing not option.

any ideas or open source implementations used?

create multiple bytearrayinputstream instances around returned arrays , use them in stream provides concatenation. instance use sequenceinputstream this.

trick implement enumeration<bytearrayinputstream> can use bytereader class.

edit: i've implemented answer, better create own inputstream instance instead. unfortunately, solution not let handle ioexception gracefully.

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final enumeration<bytearrayinputstream> basenum = new enumeration<bytearrayinputstream>() {      bytearrayinputstream baos;     boolean ended;      @override     public boolean hasmoreelements() {         if (ended) {             return false;         }          if (baos == null) {             getnextba();             if (ended) {                 return false;             }         }          return true;     }      @override     public bytearrayinputstream nextelement() {         if (ended) {             throw new nosuchelementexception();         }         if (baos.available() != 0) {             return baos;         }          getnextba();         return baos;     }      private void getnextba() {          byte[] next;         try {             next = bytereader.read();         } catch (ioexception e) {             throw new illegalstateexception("issues reading byte arrays");         }         if (next == null) {             ended = true;             return;         }         this.baos = new bytearrayinputstream(next);     } };  sequenceinputstream sis = new sequenceinputstream(basenum);