Byte and char conversion in Java

Question

If I convert a  character to byte and then back to char  that character mysteriously disappears and becomes something else  How is this possible   This is the code   char a                  line 1        byte b    byte a       line 2        char c    char b       line 3 System out println  char c          int c     Until line 2 everything is fine    In line 1 I could print  a  in the console and it would show       In line 2 I could print  b  in the console and it would show -56  that is 200 because byte is signed  And 200 is       So it s still fine    But what s wrong in line 3   c  becomes something else and the program prints    65480  That s something completely different   What I should write in line 3 in order to get the correct result

User · Answer

new String byteArray  Charset defaultCharset     This will convert a byte array to the default charset in java  It may throw exceptions depending on what you supply with the byteArray

User · Answer

A character in Java is a Unicode code-unit which is treated as an unsigned number  So if you perform c    char b the value you get is 2 16 - 56 or 65536 - 56   Or more precisely  the byte is first converted to a signed integer with the value 0xFFFFFFC8 using sign extension in a widening conversion  This in turn is then narrowed down to 0xFFC8 when casting to a char  which translates to the positive number 65480   From the language specification   5 1 4  Widening and Narrowing Primitive Conversion     First  the byte is converted to an int via widening primitive conversion    5 1 2     and then the resulting int is converted to a char by narrowing primitive conversion      5 1 3       To get the right point use char c    char   b  amp  0xFF  which first converts the byte value of b to the positive integer 200 by using a mask  zeroing the top 24 bits after conversion  0xFFFFFFC8 becomes 0x000000C8 or the positive number 200 in decimals     Above is a direct explanation of what happens during conversion between the byte  int and char primitive types   If you want to encode decode characters from bytes  use Charset  CharsetEncoder  CharsetDecoder or one of the convenience methods such as new String byte   bytes  Charset charset  or String toBytes Charset charset   You can get the character set  such as UTF-8 or Windows-1252  from StandardCharsets

[java] Byte and char conversion in Java

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