converting an if statement to a conditional operator in Java

Question

How do I simplify this code with a conditional operator in Java? This is from dr. Liang's Introduction to Java.

public class Test {
    public static void main(String[] args) {
        int i = 3;
        int j = 4;
        int k = max(i, j);
        System.out.println("The max int is " + k);
    }

    public static int max(int num1, int num2) {
        int result;

        if (num1 > num2) {
            result = num1;
        }

        else {
            result = num2;
        }

        return result;

    }
}

GhostCat · Accepted Answer · 2016-10-08 19:16:28Z

5

You can turn things into a one-liner using the conditinal ternary operator:

return (num1 > num2) ? num1 : num2;

But just for the record: it would be better to keep that max method around; simply for the sake of readability. It helps to have that functionality in its own method.

But of course: you want to read about java.lang.Math.max() which already provides exactly that functionality (not only for int, but all the other numerical primitive types as well)!

So, the real answer is: yes, use a method for that check; but don't create your own version; use the one that is already coming with Java by default. In other words: do not re-invent the wheel. Even when it is just a small wheel like this one.

answered Oct 8, 2016 at 19:16

GhostCat

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4 Comments

GhostCat Over a year ago

Sure, learning is always "different", but I guess you also learned that one theme "do not re-invent the wheel" today.

GhostCat Over a year ago

Sure, good point. Then lets reword that: one should know about existing wheels; and make a conscious decision about re-using existing wheels, or creating new ones. Both choices come with different (dis)advantages that should be taken into account when making decisions in the real world.

GhostCat Over a year ago

Whereas in IT, we have have far too many people that build their own wheels; very often ending up very much deficient compared to those that would be already available to us.

GhostCat Over a year ago

You are very welcome. I used IT to express the fact that yes, there is a broad spectrum of people creating software; and in the real world, and on stackoverflow, you are dealing with all kinds of people. Great discussion; have a good night. And for the record: I am already in bed, and I better shutdown my laptop now, too.

Elliott Frisch · Accepted Answer · 2016-10-08 19:18:37Z

4

While you could use the conditional operator ? : to implement this

public static int max(int num1, int num2) {
    return num1 > num2 ? num1 : num2;
}

But, I would prefer Math.max(int, int) like

public static int max(int num1, int num2) {
    return Math.max(num1, num2);
}

You might also choose to use varargs and support an arbitrary number of int(s). Using an IntStream you could do

public static int max(int... nums) {
    return IntStream.of(nums).max().getAsInt();
}

answered Oct 8, 2016 at 19:18

Elliott Frisch

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1 Comment

q1612749 Over a year ago

Yes, I understand Math.max would be a better choice, of course. That is just for learning purposes (it was on the chapter book's on methods).

Edmundo Santos · Accepted Answer · 2016-10-08 19:16:18Z

3

You can use a conditional ternary operator.

int k = (i > j) ? i : j;

This expression evaluates to:

If i is greather than j, assign i to k. If not, assign j to k.

answered Oct 8, 2016 at 19:16

Edmundo Santos

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Comments

HopefullyHelpful · Accepted Answer · 2016-10-14 21:05:11Z

2

This would be one way to modify your example to use the ternary operator.

You should generally keep the values in the operator short otherwise they get hard to read.

public class Test {
    public static void main(String[] args) {
        int i = 3;
        int j = 4;
        int k = max(i, j);
        System.out.println("The max int is " + k);
    }

    public static int max(int num1, int num2) {
        int result;

        result = (num1 > num2) ? num1 : num2;
        return result;

    }
}

edited Oct 14, 2016 at 21:05

HopefullyHelpful

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answered Oct 8, 2016 at 19:17

Nikhil Pathania

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