 <p>It's crashing because you have not initialized Sport *one; and you're attempting to call methods on a null pointer. You need to first create a Running object within the Activity constructor using the "new" operator like so:</p> <pre><code>one = new Running(n, time); </code></pre> <p>Create an overloaded constructor in your "Running" class that takes the appropriate arguments as well, so that you can initialize your variable as shown above.</p>