Trying to get a Boolean in Java

Question

I'm getting a compilation error in the following code, saying that operators can't be used for the boolean or double.

I want to return a boolean that indicates if x is in that range or not.

public static Boolean estaEnIntervalo (double x){           
    return (-5.0<=x<=2.0 || 0.0<x<=1.0 || 2.0<=x<5.0);              
}

Answer 1

You cannot combine relational operators this way, as you would in math. How Java interprets -5.0<=x<=2.0 :

-5.0<=x produces a boolean , but boolean<=2.0 doesn't make sense.

You must create separate expressions for each bound.

return ((-5.0<=x && x<=2.0) || (0.0<x && x<=1.0) || (2.0<=x && x<5.0));

Answer 2

-5.0<=x<=2.0 is not a valid expression. You need to use (-5.0 <= x) && (x <= 2.0), and similarly for the other checks too.

Also remember that Boolean is not the same as boolean. One is an object, and one is a primitive. As pointed out by SamTebbs33.

Answer 3

You have to split each range into two conditions conbined with AND :

return ((-5.0<=x && x<=2.0) || (0.0<x&&x<=1.0) || (2.0<=x&&x<5.0));

Now, your condition checks if x if within any of three ranges :

[-------------------------------]
                      (----]    [------------]
-5                    0    1    2            5

Since these ranges overlap, so you can simply have a single range condition :

return (-5.0<=x && x<=5.0);

Answer 4

The following is an invalid boolean expression (-5.0 <= x <= 2.0)

It must be changed to (x <= 2.0 && x >= -5.0)

In addition, you have to return a Boolean object.

return new Boolean((x <= 2.0 && x >= -5.0) || (x <= 1.0 && x > 0.0) || (x < 5.0 && x >= 2.0));

Otherwise, rearrange the expression like I did and change the return type to boolean