CODEWITHSUNDEEP
javaserial-portxmodem
sampatt
sampatt

Reputation:

compare hexadecimal values java

Duplicate: Compare hexadecimal and decimal values

I'm implementing x-modem protocol in java, I'm reading serialport and storing in byte array of size 1024. then I have converted data to string I'm getting 133 bytes in a packet,problem is I'm not enable to compare hexadecimal value in string and also in bytearray. I've to find SOH i.e. 0x01,EOT=0x02 in data, but I'm unable to understand how to do it.

Here is part of thecode:

char SOH=0X01;
public void readResponse() 
{
  byte[] buffer = new byte[1024];
  int len = -1;
  String data;
  try 
  {
    while ((len = this.getIn().read(buffer)) > -1) 
  {
  data = new String(buffer,0,len);
  time = System.currentTimeMillis();
  data = new String(buffer, 0, len);
  System.out.println("Data length is "+data.length());
  System.out.println(data);
  for(int i=0;i<carray.length;i++)
  {
    if(data.CharAt(i)==SOH)
    {
      System.out.println("SOH["+i+"]"+data.CharAt(i));
    }
  }
}

Thanks in advance.

Upvotes: 0

Views: 3259

Answers (2)

pauljwilliams
pauljwilliams

Reputation: 19225

You're comparing bytes with Strings - this is a Bad Thing, as you dont know what encoding Java is using to cnvert a given byte into a textual representation.

Use a ByteBuffer and do comparisons between raw bytes as they are read.

Upvotes: 1

Joachim Sauer
Joachim Sauer

Reputation: 308031

Don't use String/char when handling binary data. Use byte[]/byte instead. Fix that before you try to fix any other bugs.

char is a 16-bit value in Java, it's not the same as the C char (which is defined to be a byte). The closest thing to a C char in Java is the byte (which is signed, 'though).

Upvotes: 1

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