在if语句中两次使用==运算符

Question

Is it okay to do like this in java, does it work?

if (turtles.get(h).getX() == turtles.get(g).getX() == 450) { 
    //stuff here
}

Basically, i want to check if X is the same value as Y and that value should be 450.

Answer 1

No. What do you expect to happen there?

"a == b" evaluates into a boolean, so "int == (int == int)" would evaluate into "int == boolean", and you cannot compare and int and a boolean.

Besides, what kind of logic are you trying to do here? if ((a == b) && (b == c)) ?

Answer 2

No, it's not. This is because the result of a == b is a boolean. If you do a == b == c you are first comparing a == b which will return true or false and then comparing that truth value to c .

Not what you want to do, usually!

Note that this trick can work for assignment because the result of a = b is b (the new value of a ) which means a = b = c or even (a = b) == c come in useful occasionally.

Answer 3

No. It is the same as (turtles.get(h).getX() == turtles.get(g).getX()) == 450 - "incomparable types". if(turtles.get(h).getX() == 450 && turtles.get(g).getX() == 450) .

Answer 4

Or avoid all the less-readable (and error-prone) repetition with a helper method...

public boolean areEqual( int a, int b, int c )
{
    return ( a == b ) && ( b == c ) ;
}

Answer 5

That won't work, because the == operator is binary.
And even if it worked sequentially, the first set would return a boolean, which won't work against the integer that follows.

Answer 6

No it won't work, as explained in the other posts. But you could do

if (turtles.get(h).getX() - turtles.get(g).getX() + 450 == 0)