Wednesday, October 9, 2019

Java: Optional or just null

So I was making a simple game on the weekend, as we do, and there was a simple (again) player class:

public class Player {
    public final String name;
    private Team team;
    public boolean friendly(Player other) {
        return team.has(other);

But the obvious thing is, can it be null? Yes it can, in cases where the player does not have a team. So I said 'Let's try Optional, why not`.

    private Optional<Team> team;

Then the possibilities for the return statement where limitless from the most straight forward to the most elegant:

    return team.isPresent() && team.get().has(other)

    return -> i.has(other)).orElse(false);

    return team.filter(i -> i.has(other)).isPresent();

    return team.orElse(Team.EMPTY).has(other);
Or I could remove the Optional again and have just the old thing:

    return team != null && team.has(other);

But 'How will you remember that it can be null in other places?' said the guy. Its a private field, how many places are there really. Also it is logical to null so I would probably check it anyhow.


Saturday, August 31, 2019

Security: Just remove everything -Boss

Let's consider for a fact that we have a very pseudo secure environment. Pseudo referring to something that has been purified of everything that can be a source of vulnerability. So we have no compilers, no runtimes and of course no internet. Also we have some physical security, the whole thing is locked in a box with only the cables for monitor, keyboard etc. and a wire with a button on it to start the machine.

Boss asks, is there any way for someone to harm this system.

Just ctrl-A and delete, dude.

PS: My task is too keep the antivirus up to date....


Sunday, July 21, 2019

Javascript: Do it like php!

So, I just wanted a simple thing... I had a static html page where I wanted to put some things in dynamically: a simple date at the start and an extended date in the middle of the text. (Also what is server side?)

Pure elegant javascript:

.... <span data-value="simple"></span> ....


var data = {
    simple: gen_simple(),

for (var i of document.querySelectorAll('[data-value]')) {
    i.innerHTML = data[i.getAttribute('data-value')];


Php infected javascript:

.... <script>document.write(gen_simple())</script> ....

plus if in 'I was never here' mode:

for (var i of document.querySelectorAll('script')) i.parentNode.removeChild(i);


Thursday, January 10, 2019

Java: Iterable iterator

We all have been in a position with an Iterator in our hands and trying to pass it to a for each loop. And then for some reason that is totally crazy for a second an error pops up:

"Can only iterate over an array or an instance of java.lang.Iterable"

What... a ok... and then what? You could just fix your logic in order or just google for "java iterator to iterable". But could you just make the iterator also an iterable somehow.

Step one, obviously, add the Iterable interface to your iterator:

public class SuperIterator<T> implements Iterator<T>, Iterable<T> {

Step two, add the missing method by return itself as its iterator:

public Iterator<Character> iterator() {
    return this;