Two questions about a simple java card applet

[Danieken]

I am a newbie to java card. I have found a simple applet code by google and i understand its function.
Here is the applet.

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package helloworld;

import javacard.framework.*;

public class helloworld extends Applet
{
    private static final byte[] javacard = {(byte)'J',(byte)'a',(byte)'v',(byte)'a',(byte)' ',(byte)'C',(byte)'a',(byte)'r',(byte)'d',(byte)'!',};
    private static final byte JC_CLA = (byte)0x80;
    private static final byte JC_INS = (byte)0x00;
    
   public static void install(byte[] bArray, short bOffset, byte bLength) 
   {
      new helloworld().register(bArray, (short) (bOffset + 1), bArray[bOffset]);
   }

   public void process(APDU apdu)
   {
      if (selectingApplet())
      {
         return;
      }

      byte[] buf = apdu.getBuffer();
      
      byte CLA = (byte) (buf[ISO7816.OFFSET_CLA] & 0xFF);
        byte INS = (byte) (buf[ISO7816.OFFSET_INS] & 0xFF);
        
        if (CLA != JC_CLA)
        {
            ISOException.throwIt(ISO7816.SW_CLA_NOT_SUPPORTED);
        }
        
      switch (buf[ISO7816.OFFSET_INS])
      {
      case (byte)0x00:
         OutPut(apdu);
         break;
      default:
         ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
      }
   }
   
   private void OutPut( APDU apdu)
        {
        byte[] buffer = apdu.getBuffer();
        short length = (short) javacard.length;
        Util.arrayCopyNonAtomic(javacard, (short)0, buffer, (short)0, (short) length);
        apdu.setOutgoingAndSend((short)0, length);
        }
}

If you send "80 00 00 00 00", it returns "Java Card!" , as shown in the figure.

The first question:
I don't understand why the programmer used &0xFF in lines :

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byte CLA = (byte) (buf[ISO7816.OFFSET_CLA] & 0xFF);
byte INS = (byte) (buf[ISO7816.OFFSET_INS] & 0xFF);

The second question: Why does the programmer use the expression "+ 1"?

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new helloworld().register(bArray, (short) (bOffset + 1), bArray[bOffset]);

Thanks.

[marjkbadboy]

Q1. As far as I know, this line
byte CLA = (byte) (buffer[ISO7816.OFFSET_CLA] & 0xFF)
is equal to the line
byte CLA = buffer[ISO7816.OFFSET_CLA]

[ThePhoenyx]

The "& 0xFF" is ANDing the CLA byte with FF. It's normally used as a way to isolate one bit or set of bits to see if it's set or not, such as F1 AND checkbyte == 0 would check for any of bits 1 and 5-8 being set. Why in sample you showed they used FF I'm not sure, I'd have to see more of the code.