What's wrong with this Java syntax?

Question

height[left] < height[right]? left++ : right--;

I want to user the above syntax to replace if/else statement. I think it follows (condition)? doX(): doY() but there's somthing wrong.

Thank you!

Can you show us this ternary expression in the context of your code? — Tim Biegeleisen, Apr 12 '16 at 14:43

score 3 · Accepted Answer · answered Apr 12 '16 at 14:44

3

The ternary operator is an expression, not a statement. You're not assigning the result of the expression to anything, so the compiler doesn't like it.

If you mean this as a statement, use if instead of the ternary operator:

if (height[left] < height[right]) {
    left++;
} else {
    right--;
}

answered Apr 12 '16 at 14:44

Jesper

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@ĐăngKhoaHuỳnh Why? You don't know if the result should be the return value of a method or not, the question doesn't indicate that. – Jesper Apr 12 '16 at 14:48
Oh sorry, I think you are using `if` for ternary operator as the same case. – Đăng Khoa Huỳnh Apr 12 '16 at 14:50

score 0 · Answer 2 · edited Jun 20 '20 at 09:12

It is wrong because the operation is not assigning a value to anything...

ternary operations have a return

Example:

int a=0;
int b=0;
int left=0;
int right=0;
int pos=0;
pos = a < b? left++ : right--;

as you see the variable pos get assigned as result of the ternary operation

in your case you are missing the variable were left++ or right-- is going to be assigned:

??? = height[left] < height[right]? left++ : right--;

What's wrong with this Java syntax?

2 Answers2

Example: