I'm working on a 'tabindex' defect in an application that works fine in Firefox and Chrome, but not Internet Explorer. The 'tabindex' is set through a JSP by a static 'int', which is incremented each time it is used.
private static short tabIndex = 1;
sb.append("<select tabindex='").append(tabIndex++) ...
Internet Explorer has a maximum 'tabindex' of 32767 (Short.MAX_VALUE). So I can change the int to a short, but after it reaches the maximum, it will tick around to Short.MIN_VALUE.
Objects with a negative tabIndex are omitted from the tabbing order.
So I need it to progress from Short.MAX_VALUE to zero.
Obviously, it is trivial to write some code to do this, but I wondered if there is some clever short-hand way that I can increment to a strictly positive number, or some other data type I can use.
You can make sure that the MSB is always 0 by ANDing the value with 0x7FFF.
short s = 32767;
short s1 = (short)(s & 0x7FFF); // s1 = 32767 (or 0x7FFF)
s++; // s = -32768 (or 0x8000)
short s2 = (short)(s & 0x7FFF); // s2 = 0
You might want to extract the incrementation and bitmasking to its own method and just use that inside append.
I'm not condoning this code, because it's not very clear and frankly returning from assignment is not something I'd use, but the following would be a very short version:
public short incIndex() {
return tabIndex = (short)(tabIndex+1 & 0x7FFF);
}
...append(incIndex())...