job1

/********* Block *********/
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
 
/**
 * Created by hosang on 2017. 12. 2..
 */
public class Block {
 
  private int blockSize;            // Ignore for now.
  private BlockHeader blockHeader;
  private int transactionCount;    // Ignore for now.
  private Object[] transactions;
 
  public Block(BlockHeader blockHeader, Object[] transactions){
    this.blockHeader = blockHeader;
    this.transactions = transactions;
  }
 
  public String getBlockHash() throws NoSuchAlgorithmException {
 
    MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
 
    // Hash twice - Not a K-pop girl group.
    byte[] blockHash = messageDigest.digest(blockHeader.toByteArray());
    blockHash = messageDigest.digest(blockHash);
 
    return new String(blockHash,0,blockHash.length);
  }
 
}