Java check two arguments either both not null or both null elegantly

Question

I used spring boot to develop a shell poject used to send email, e.g.

sendmail -from foo@bar.com -password  foobar -subject "hello world"  -to aaa@bbb.com

If the

from

and

password

arguments are missing I use a default sender and password, e.g.

noreply@bar.com

and

123456

.

So if the user passes the

from

argument they must also pass the

password

argument and vice versa, that is to say either both are non-null, or both are null.

How to check this elegantly?

Now my way is

if ((from != null && password == null) || (from == null && password != null)) {

    throw new RuntimeException("from and password either both exist or both not exist");

}

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Answer 1

There is a way using ^ (XOR) operator:

if (from == null ^ password == null) {
    // use RuntimeException if you need to
    throw new IllegalArgumentException("message"); 
}

if condition will be true if only one variable is null.

But I think usually it's better to use two if conditions with different exception message. You can't define what went wrong using single condition.

Java check two arguments either both not null or both null elegantly

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