CODEWITHSUNDEEP
java
rolory
rolory

Reputation: 362

False expression in if condition goes true

I studied the Conditions material today and got some homework, some of them are pretty easy and some of them are tricky to implement.
However, I got this following code:

boolean bool1, bool2, bool3;
bool1 = false;
bool2 = true;
bool3 = true;
    if(bool1 == true || bool2 == true && bool3 == true)
        System.out.println("true");
    else
        System.out.println("false");

I don't understand why this program returning true while there's a false statement - bool1 is declared as FALSE in the beginning of the program, and when it's checked (bool1 == true) the if should return false.

Upvotes: 1

Views: 1182

Answers (7)

Berendschot
Berendschot

Reputation: 3104

The problem is in the following line:

if(bool1 == true || bool2 == true && bool3 == true)

In this statement you're asking for two conditions:

  1. Bool1 == true OR
  2. Bool2 == true && Bool3 == true.

As you might have mentioned || means 'OR'. In you're code you have declared both Bool2 and Bool3 as true. So the second condition in the if-statement is correct and will cause the block to continue, which in your case will print True.

What I think you're trying to do is the following:

  1. Bool1 OR Bool2 (or both) is/are true. AND
  2. Bool3 is true.

In that case you'll have to use the following code:

if((bool1 == true || bool2 == true) && bool3 == true)

Upvotes: 1

Yassin Hajaj
Yassin Hajaj

Reputation: 21965

Let's break this down a bit :

bool1 == true // FALSE : because bool1 has the value of "false"
bool2 == true // TRUE : because bool2 has a value of "true"
bool3 == true // TRUE : because bool2 has a value of "true"

Let's go back to the expression and replace :

(FALSE || TRUE && TRUE)

FALSE || ... : Since it is a || and the first value is false, we have to check the second value.

TRUE && ... : Now we're checking the second value, since it is true and we are using &&, we have to check the second expression. Since in this case it is true, the whole expression becomes TRUE

More Information

Wiki's Page for Boolean Expressions

Upvotes: 1

xFunkyTImes
xFunkyTImes

Reputation: 107

That's because || means 'or' and && means 'and'. So basically in your case, if bool1 OR bool2 are true, the condition is correct. Try your code changing the value of bool2to false aswell, and you will see that the program will return you a false statement.

Upvotes: 0

Alexandru Babeanu
Alexandru Babeanu

Reputation: 59

The condition returns true because of the OR operator: ||. This operator returns true if at least one of the two expressions next to it is true. In your case, you have true or false, therefore true.

Upvotes: 0

Mohammed Aouf Zouag
Mohammed Aouf Zouag

Reputation: 17132

if(bool1 == true || bool2 == true && bool3 == true)

&& is prior to || , so bool2 == true && bool3 == true is evaluated first (== true). The condition becomes:

if(bool1 == true || true)

which evaluates to true also. Hence you get "true" as output.

Upvotes: 0

bbakiu
bbakiu

Reputation: 281

|| stand for OR. If the left or the right side of OR is TRUE then the result is TRUE . The right side is TRUE and this is why you get the result TRUE.

Upvotes: 0

user4398985
user4398985

Reputation: 

if(bool1 == true || bool2 == true && bool3 == true)
            System.out.println("true");

The above if statement says, if either bool1 or bool2 is true, and if bool3 is true print me "true"

Read more about || operator.

The above operator means, atleast one should be true out of two expressions.

&&, all expressions must be true. ||, atleast one is enough.

Upvotes: 0

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