How do I make a counting app?

How do I make an app that counts button clicks? I'm not sure if I even need to set an onClick action, though. I'm also not sure what to do for Java, although I did do something similar to this before. The xml I have so far is

<Button
    android:id="@+id/countButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="count"
    android:text="Add One" />

<Button
    android:id="@+id/resetButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="reset"
    android:text="Reset" />