Reverse a boolean value?

Question

In Java (or, to be honest, any computer language), to increment an int, you do as so:

// Option 1 - efficient
int x = 0;
x++;
// x = 1

// Option 2 - works, but is ugly
int y = 0;
y = y + 1;
// y = 1;

How would you do this to a boolean?

// Standard way to
// oppose a boolean
boolean isTrue = false;
if(isTrue){
    isTrue = false;
} else if(!isTrue){
    isTrue = true;
}

Is there not a shortcut to change a boolean? For example, if the boolean was true, is there a way to change it with just a small shortcut like x++;?

I actually prefer `++/--` *not* being part of a language. They are very useful for "C-like" code, but can also lead to abuse in expressions. — user2864740, Apr 27 '14 at 17:31
Actually `a += 1` (in Java this is also an expression, although if I were designing a language all assignments would only be statements, but I digress). — user2864740, Apr 27 '14 at 17:38

score 10 · Accepted Answer · answered Apr 27 '14 at 17:27

10

You can use ! to flip its value.

isTrue = !isTrue;

! inverts the value of a boolean.

answered Apr 27 '14 at 17:27

Alexis C.

91,686
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1

So this would work: `boolean a = false; a = !a; // a now equals true?` – user3422952 Apr 27 '14 at 17:29
@user3422952 Yes, try it. This is about the simplest thing you could test. – Jonathon Reinhart Apr 27 '14 at 17:29
Haha, I'm away from my programming computer - thanks for the help! – user3422952 Apr 27 '14 at 17:34
@user3422952 There exists online compilators such as http://ideone.com ;) – Alexis C. Apr 27 '14 at 17:34

score 2 · Answer 2 · answered Apr 27 '14 at 17:27

2

No, there is no such shortcut in Java.

What you can do is use the logical complement operator to reverse the value

!isTrue

but you will have to reassign the result.

answered Apr 27 '14 at 17:27

Sotirios Delimanolis

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Reverse a boolean value?

2 Answers2