So far from I have been searching through the net, the statement always have if and else condition such as a ? b : c. I would like to know whether the if ternary statement can be used without else.
Assuming i have the following code, i wish to close the PreparedStatement if it is not null
(I am using Java programming language.)
PreparedStatement pstmt;
//....
(pstmt!=null) ? pstmt.close : <do nothing>;
No, you cannot do that. Instead try this:
if(bool1 && bool2) voidFunc1();
Just write it out?
if(pstmt != null) pstmt.close();
It's the exact same length.
Why using ternary operator when you have only one choice?
if (pstmt != null) pstmt.close();
is enough!
Ternary if operator is the particular ternary operator. One of a kind.
From Wiki:
In mathematics, a ternary operation is an n-ary operation with n = 3.
It means all 3 operands are required for you.
As mentioned in the other answers, you can't use a ternary operator to do this.
However, if the need strikes you, you can use Java 8 Optional and lambdas to put this kind of logic into a single statement:
Optional.of(pstmt).ifPresent((p) -> p.close())
A ternary operation is called ternary beacause it takes 3 arguments, if it takes 2 it is a binary operation.
And as noted above, it is an expression returning a value.
If you omit the else you would have an undefined situation where the expression would not return a value.
So as also noted in other answer, you should use an if statement.
You cannot use ternary without else, but to do a "if-without-else" in one line, you can use Java 8 Optional class.
PreparedStatement pstmt;
//....
Optional.ofNullable(pstmt).ifPresent(pstmt::close); // <- but IOException will still happen here. Handle it.
Well in JavaScript you can simply do:
expression ? doAction() : undefined
since that's what's literally actually happening in a real if statement, the else clause is simply undefined. I image you can do pretty much the same thing in (almost?) any programming language, for the else clause just put a null-type variable that doesn't return a value, it shouldn't cause any compile errors.
Yes you can do that actually (in JavaScript at least):
condition && x = true;
or (in JavaScript, and there might be a similar way to do this in Java):
void(condition && x = true)
来源：https://stackoverflow.com/questions/20053257/if-without-else-ternary-operator