Unsigned types in java

Question

hi there,
i was wondering if there is any way to handle unsigned int in java. im making some byte processing and i have a "switch case" statement like below
so when it comes at 0x80 it does not enter the case because it converts it as -1.
im using java 1.7
ByteBuffer record;
pkgId = record.get();
switch ((int) pkgId) {
case 0x75:
break; /* 117 */
case 0x7D:
break; /* 125 */
case 0x80:
break; /* 128 */
case 0x82:
break; /* 130 */
case 0x86:
break; /* 134 */
case 0x87:
break; /* 135 */
}

Answer 1

user8999602 wrote:
hi there,
i was wondering if there is any way to handle unsigned int in java.Use a long.
im making some byte processing and i have a "switch case" statement like below
so when it comes at 0x80 it does not enter the case because it converts it as -1.
im using java 1.7
ByteBuffer record;
pkgId = record.get();
switch ((int) pkgId) {
case 0x75:
break; /* 117 */
case 0x7D:
break; /* 125 */
case 0x80:
break; /* 128 */
case 0x82:
break; /* 130 */
case 0x86:
break; /* 134 */
case 0x87:
break; /* 135 */
}Looks more like you want an unsigned byte. The usual approach to that is to use an int, but you need to mask it. The byte 0x80 has the value -128, so when you simply cast to an int, it sign extends it, and you get 0xFFFFFF80, which is an int value of -128.
int pkgIdInt = pkgId & 0xFF;
switch (pkgIdInt);Alternatively, you could just cast each case value to byte, but that's too cluttered for my taste.