Java `if` statement and `else if` not working as expected

Question

I have the user enter a list of 5 ints into an int[]. I then go through those ints in the int[] with a simple for statement. I have an int variable declared called "evens." If the number in the int[] at i %2 == 0 , evens++;

Now I have the if statement:

if (evens !=2 || evens!=3) {
  System.out.print("This was called because " + evens + " is not equal to 2 or 3");
}

The problem is that this is being called no matter what the value in evens is. It can be 5 or 3 and still gets called. I've been using C# recently but this is simple Java.

Whole code:

int evens = 0;
    for(int i=0; i<chosenNumbers.length; i++) {
        if(chosenNumbers[i] %2 ==0)
            evens++;
    }

System.out.println("You chose "+evens+" even numbers and " + (chosenNumbers.length-evens) + " odd numbers.");

    if (evens !=2 || evens!=3) {
        System.out.print("This was called because " + evens + " is not equal to 2 or 3");
    } else if (evens==2 || evens==3) {
        System.out.print(evens +" equals 2 or 3");
    }

Try saying evens !=2 || evens!=3 in English: "if evens differs from 2 or evens differs from 3, then ....". And then you'll realize that any number always differs from 2 or differs from 5. You probably mean and instead of or. — Erwin Bolwidt
– Erwin Bolwidt, Commented Jan 12, 2016 at 1:39

AntonH · Accepted Answer · 2016-01-12 01:35:34Z

2

You need to replace:

if(evens !=2 || evens!=3) {
    System.out.print("This was called because " + evens + " is not equal to 2 or 3");
}

with:

if(evens !=2 && evens!=3) {
    System.out.print("This was called because " + evens + " is not equal to 2 or 3");
}

If you use the logical OR ||, you will always enter the block, as the only way it would not enter is it evens is equal to 2 and 3 at the same time, which isn't possible.

answered Jan 12, 2016 at 1:35

AntonH

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Comments

Heshan · Accepted Answer · 2016-01-12 01:50:17Z

0

you can use

if(!(evens ==2 || evens==3)) {
        System.out.print("This was called because " + evens + " is not equal to 2 or 3");
} else {
        System.out.print(evens +" equals 2 or 3");
}

answered Jan 12, 2016 at 1:50

Heshan

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4 Comments

YoYo Over a year ago

@MrAwesome8, not true ... boolean algebra can be correctly applied: !(a || b) is equivalent to !a && !b. This is part of De Morgan's laws. Devils and Details ...

Erwin Bolwidt Over a year ago

@JoD. Exactly, and that's why this answer is "Not Useful" as it gives the same answer as AntonH gave 12 minutes earlier, but without any explanation. There's no need for duplicate answers.

YoYo Over a year ago

@ErwinBolwidt I can agree to that as a reason for flagging/downvoting, but the first comment should be retracted as incorrect.

YoYo Over a year ago

Also @Heshan was earlier to respond and did incorporate the simpler else in his answer. That is no need for the else if (...). Would be nice if the poster would highlight that in his answer. If not the accepted answer can highlight that part too.

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