How to display a hex/byte value in Java

问题

int myInt = 144;
byte myByte = /* Byte conversion of myInt */;

Output should be myByte : 90 (hex value of 144).

So, I did:

byte myByte = (byte)myInt;

I got output of myByte : ffffff90. :(

How can I get rid of those ffffffs?

回答1:

byte is a signed type. Its values are in the range -128 to 127; 144 is not in this range. There is no unsigned byte type in Java.

If you are using Java 8, the way to treat this as a value in the range 0 to 255 is to use Byte.toUnsignedInt:

String output = String.format("%x", Byte.toUnsignedInt(myByte));

(I don't know how you formatted the integer for hex output. It doesn't matter.)

Pre-Java 8, the easiest way is

int byteValue = (int)myByte & 0xFF;
String output = String.format("%x", byteValue);

But before you do either of those, make sure you really want to use a byte. Chances are you don't need to. And if you want to represent the value 144, you shouldn't use a byte, if you don't need to. Just use an int.

回答2:

Thank you @ajb and @sumit, I used both the answers,

int myInt = 144;

byte myByte = (byte) myInt;

char myChar = (char) (myByte & 0xFF);

System.out.println("myChar :"+Integer.toHexString(myChar));

o/p,

myChar : 90

回答3:

Use the following code:

int myInt = 144;
byte myByte = (byte)myInt;
System.out.println(myByte & 0xFF);

In Java 8, use Byte.toUnsignedInt(myByte) as ajb said.

来源：https://stackoverflow.com/questions/29553993/how-to-display-a-hex-byte-value-in-java