Output buffer as binary, similar to xxd in java

README.md

Simple XXD Style output from a ByteBuffer.

Refactored here without testing, so probably no-longer compiles - but should be a good starting point should I need it again.

xxdOutput.java

public class XxdOutputter {
  
  protected void printLineNumber(PrintStream stream, int idx) {
    stream.printf("%08x:", idx);
  }
  
  protected void printHexCharOrSpace(PrintStream stream, ByteBuffer byteBuffer, int offset) {
      if (offset < byteBuffer.length()) {
        stream.printf("%02x", byteBuffer.get(offset));
      } else {
        stream.printf("  ");
      }
  }
  
  protected void printHexBytes(PrintStream stream, ByteBuffer byteBuffer, int offset ) {
    int bytes = byteBuffer.length();
    for (int j = 0; j < 8; ++j) {
      stream.printf(" ");
      printHexCharOrSpace(stream, byteBuffer, offset+2*j);
      printHexCharOrSpace(stream, byteBuffer, offset+2*j+1);
    }
  }
  
  protected void printPrinableChars(PrintStream stream, ByteBuffer byteBuffer, int offset) {
    int bytes = byteBuffer.length();
    for (int j = 0; j < 16; ++j) {
      if (offset + j < bytes) {
        byte b = byteBuffer.get(offset + j);
        if (Character.isISOControl((char) b)) {
          stream.printf(".");
        } else {
          stream.append((char) b);
        }
      } else {
        stream.append(' ');
      }
    }
  }
  
  public String xxdStyleByteOutput(ByteBuffer byteBuffer, int startOffset, int length) {
    ByteArrayOutputStream bstream = new ByteArrayOutputStream();
    try (PrintStream stream = new PrintStream(bstream)) {
      for (int idx = 0; idx < bytes; idx += 16) {
        printLineNumber(idx + startOffset);
        printHexBytes(stream, byteBuffer, idx + startOffset);
        stream.printf("  ");
        printPrintableCharacters(stream, bytBuffer, idx + startOffset);
        stream.printf("\n");
      }
    }
    return bstream.toString();
  }
}