A software engineer sharing thoughts on code quality, conferences, and continuous learning. Zola 2017-11-29T00:00:00+00:00 https://xballoy.github.io/tags/java/feed.xml Xavier Balloy 2017-11-29T00:00:00+00:00 2017-11-29T00:00:00+00:00 Xavier Balloy https://xballoy.github.io/blog/how-to-avoid-conditional-in-your-code/

<p>A couple of weeks ago I was asked to share how I avoided <code>if</code> in my code at the Global Day of Coderetreat 2017.</p>

<p>A couple of weeks ago I was asked to share how I avoided <code>if</code> in my code at the Global Day of Coderetreat 2017.</p> <span id="continue-reading"></span> <p><strong>DISCLAIMER</strong>: this solution was produced during a kata where we forced ourselves to code under certain conditions (no <code>if</code> in this case). It is not the only solution (you can use polymorphism for example) and is probably not a good pattern to solve this specific case in a real project.</p> <p>In my implementation of Conway's Game of Life, I have the following method to know if a cell will be <code>DEAD</code> or <code>ALIVE</code> in the next iteration.</p> <pre class="giallo" style="color-scheme: light dark; color: light-dark(#24292E, #E1E4E8); background-color: light-dark(#FFFFFF, #24292E);"><code data-lang="java"><span class="giallo-l"><span style="color: light-dark(#D73A49, #F97583);">public</span><span> Status</span><span style="color: light-dark(#6F42C1, #B392F0);"> newStatusFor</span><span>(</span><span style="color: light-dark(#D73A49, #F97583);">int</span><span> neighborsCount</span><span>)</span><span> {</span></span> <span class="giallo-l"><span style="color: light-dark(#D73A49, #F97583);"> if</span><span> (</span><span>neighborsCount </span><span style="color: light-dark(#D73A49, #F97583);">&lt;</span><span style="color: light-dark(#005CC5, #79B8FF);"> 2</span><span style="color: light-dark(#D73A49, #F97583);"> ||</span><span> neighborsCount </span><span style="color: light-dark(#D73A49, #F97583);">&gt;</span><span style="color: light-dark(#005CC5, #79B8FF);"> 3</span><span>)</span><span> {</span></span> <span class="giallo-l"><span style="color: light-dark(#D73A49, #F97583);"> return</span><span> Status</span><span>.</span><span>DEAD</span><span>;</span></span> <span class="giallo-l"><span> }</span></span> <span class="giallo-l"><span style="color: light-dark(#D73A49, #F97583);"> return</span><span> Status</span><span>.</span><span>ALIVE</span><span>;</span></span> <span class="giallo-l"><span>}</span></span></code></pre> <p>Because we have a small finite number of possibilities (a cell has up to 8 neighbors), I did as follows:</p> <pre class="giallo" style="color-scheme: light dark; color: light-dark(#24292E, #E1E4E8); background-color: light-dark(#FFFFFF, #24292E);"><code data-lang="java"><span class="giallo-l"><span style="color: light-dark(#D73A49, #F97583);">private</span><span style="color: light-dark(#D73A49, #F97583);"> static</span><span> ImmutableMap</span><span>&lt;</span><span style="color: light-dark(#D73A49, #F97583);">Integer</span><span>,</span><span style="color: light-dark(#D73A49, #F97583);"> Status</span><span>&gt;</span><span> neighborsRules</span><span style="color: light-dark(#D73A49, #F97583);"> =</span><span> ImmutableMap</span><span>.</span><span style="color: light-dark(#D73A49, #F97583);">&lt;</span><span>Integer</span><span>,</span><span> Status</span><span style="color: light-dark(#D73A49, #F97583);">&gt;</span><span style="color: light-dark(#6F42C1, #B392F0);">builder</span><span>(</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">0</span><span>,</span><span> Status</span><span>.</span><span>DEAD</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">1</span><span>,</span><span> Status</span><span>.</span><span>DEAD</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">2</span><span>,</span><span> Status</span><span>.</span><span>ALIVE</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">3</span><span>,</span><span> Status</span><span>.</span><span>ALIVE</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">4</span><span>,</span><span> Status</span><span>.</span><span>DEAD</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">5</span><span>,</span><span> Status</span><span>.</span><span>DEAD</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">6</span><span>,</span><span> Status</span><span>.</span><span>DEAD</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">7</span><span>,</span><span> Status</span><span>.</span><span>DEAD</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">put</span><span>(</span><span style="color: light-dark(#005CC5, #79B8FF);">8</span><span>,</span><span> Status</span><span>.</span><span>DEAD</span><span>)</span></span> <span class="giallo-l"><span> .</span><span style="color: light-dark(#6F42C1, #B392F0);">build</span><span>(</span><span>)</span><span>;</span></span> <span class="giallo-l"></span> <span class="giallo-l"><span style="color: light-dark(#D73A49, #F97583);">public</span><span> Status</span><span style="color: light-dark(#6F42C1, #B392F0);"> newStatusFor</span><span>(</span><span style="color: light-dark(#D73A49, #F97583);">int</span><span> neighborsCount</span><span>)</span><span> {</span></span> <span class="giallo-l"><span style="color: light-dark(#D73A49, #F97583);"> return</span><span> neighborsRules</span><span>.</span><span style="color: light-dark(#6F42C1, #B392F0);">get</span><span>(</span><span>neighborsCount</span><span>)</span><span>;</span></span> <span class="giallo-l"><span>}</span></span></code></pre> <p>In this case, I just return the value of the enum but I could have returned a <code>Function</code> and done something more complicated.</p> <h2 id="conclusion">Conclusion</h2> <ul> <li><strong>When to use</strong>: you have a small finite number of possibilities</li> <li><strong>Benefit</strong>: if you put a <code>Function</code> in the value it's easy to modify it without changing the existing code (open/closed principle)</li> </ul>