Comparing byte and int in Java

Yet another blog title of mine with "in Java" at the end :)

Anyway, one of the most confusing aspects of dealing with byte in Java was its actual value range. Based on some simple JUnit tests I made, I got the following output:

0 byte = 0 int
1 byte = 1 int
126 byte = 126 int
127 byte = 127 int
-128 byte = 128 int
-127 byte = 129 int
-2 byte = 254 int
-1 byte = 255 int

Interesting ....

From here we can deduce:
1) byte goes from 0 to 127 then -128 to -1
2) the range above actually corresponds to integer values of 0 to 127 then 128 to 255

Here is the JUnit test case which produced the above output. Note that Java does not allow byte values:
1) beyond or equal 128 and;
2) less or equal to -129
... which explains the remarked code portions below.

import static org.junit.Assert.*;
import org.junit.Test;

public class BaitTest {
 
 @Test
 public void printNegativeByte() {
  byte baitValue;
  int intValue;
  
  baitValue = 0;
  intValue = baitValue & 0xFF;
  System.out.println(baitValue + " byte = " +  intValue + " int");

  baitValue = 1;
  intValue = baitValue & 0xFF;
  System.out.println(baitValue + " byte = " +  intValue + " int");

  baitValue = 126;
  intValue = baitValue & 0xFF;
  System.out.println(baitValue + " byte = " +  intValue + " int");

  baitValue = 127;
  intValue = baitValue & 0xFF;
  System.out.println(baitValue + " byte = " +  intValue + " int");

//  baitValue = 128;
//  intValue = baitValue & 0xFF;
//  System.out.println(baitValue + " byte = " +  intValue + " int");

//  baitValue = -129;
//  intValue = baitValue & 0xFF;
//  System.out.println(baitValue + " byte = " +  intValue + " int");

  baitValue = -128;
  intValue = baitValue & 0xFF;
  System.out.println(baitValue + " byte = " +  intValue + " int");

  baitValue = -127;
  intValue = baitValue & 0xFF;
  System.out.println(baitValue + " byte = " +  intValue + " int");

  baitValue = -2;
  intValue = baitValue & 0xFF;
  System.out.println(baitValue + " byte = " +  intValue + " int");

  baitValue = -1;
  intValue = baitValue & 0xFF;
  System.out.println(baitValue + " byte = " +  intValue + " int");
 }
 
}