问：StacyM
在Android的开发过程中，我用的是Coursera类别，以下是我想要实现的静态效果图：

目前，我采用的代码是：
XML:

<Button
        android:id="@+id/startbutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/leftfoot"
        android:layout_alignRight="@+id/leftfoot"
        android:onClick="startRhythmandAnimation"
        android:text="@string/start_button" />

Java:

public class Assignment3MainActivity extends Activity {

private View mMileTimeGoal;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_assignment3_main);
    mMileTimeGoal = findViewById(R.id.miletimegoal);
}

public void startRhythmandAnimation () {
    String MileTime = mMileTimeGoal.getContext().toString();
    String[] time_array = MileTime.split(":");
    int hours = Integer.parseInt(time_array[0]);
    int minutes = Integer.parseInt(time_array[1]);
    int seconds = Integer.parseInt(time_array[2]);
    int duration = 3600 * hours + 60 * minutes + seconds;
    int steps_per_second = 3;

    int running_rate = duration * steps_per_second;

    View rightfoot = findViewById(R.id.rightfoot);
    View leftfoot = findViewById(R.id.leftfoot);

    rightfoot.setVisibility(View.VISIBLE);
    Animation anim = AnimationUtils.makeInChildBottomAnimation(this);
    rightfoot.startAnimation(anim);

    leftfoot.setVisibility(View.VISIBLE);
    leftfoot.startAnimation(anim);
}

我应该采用什么算法，来完成左、右脚的淡入淡出的“运动”呢？需要设定一种循环运动的定时器吗？

原问题：Android - How can I make an animation of an image occur at a certain interval?