Elegant way to code if (10 < x < 20)
Is there an elegant way in Java to code:
if (10 < x < 20) {
...
}
i.e. "if开发者_C百科 x is between 10 and 20"
rather than having to write
if ((x > 10) && (x < 20)) {
...
}
Thanks!
No. The <
operator always compares two items and results in a boolean value, so you cannot chain them "elegantly". You could do this though:
if (10 < x && x < 20)
{
...
}
Kenny nailed it in the comments.
if (10 < x && x < 20)
You want to keep them either both less-than or both greater-than; reversing the direction of the comparison makes for a confusing bit of logic when you're trying to read quickly.
No but you can re-arrange it to make it better, or write a wrapper if it irks you:
if (InRange(x, 10, 20)) { ... }
Or, as Carl says:
if (new Range(10, 20).contains(x)) { ... }
Though personally, I don't see the point. It's a useless abstraction. The bare boolean statement is perfectly obvious.
Though, now that I think about it, and in light of Carl's comment below, there are times when a Range is a perfectly valid and useful abstraction (e.g. when dealing with Feeds). So, depending on the semantics of x
, maybe you do want an abstraction.
if(x < 20)
{
if(x > 10)
{
//...
}
}
OR
if(x > 10)
{
if(x < 20)
{
//...
}
}
The only thing you can do is loose the extra parenthesis since the &&
has a lower precedence than >
and <
:
if (x > 10 && x < 20) {
...
}
Other than that: there's no shorter way.
The FASTEST way is a switch.
EDIT:
switch(x) {
case 10:
case 11:
case 12:
case 13:
...
case 19: System.out.println("yes");
}
is compiled into a jump table, not a long series of ifs.
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