What is the best way to declare on UI component in android with Kotlin? : <p>I'm trying to build android application using Kotlin for the first time.</p>

<p>I want to declare on some buttons outside the OnCreate method and i can initialize them only Inside this function with findViewById.</p>

<p>Can i declare in simple and clean code like in java?</p>

<pre><code>private Button btnProceed;
</code></pre>

<p>Because when converting it to Kotlin it look like:</p>

<pre><code>private var btnProceed: Button? = null
</code></pre>

<p>And then when initialize OnClick function need to add ! sign:</p>

<pre><code>btnProceed!!.setOnClickListener
</code></pre>

<p>What is the right and cleanest way? </p>
