系列文章之一，本系列文章将为读者分享国外最优质的精彩问与答，供读者学习和了解国外最新技术，本文为大家讲解在Android中，如何以特定的时间间隔为图片添加动画效果。

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:

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<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:

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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？

我觉得，你可以采用如下代码:

Activity

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private Handler mHandler;    private long mInterval = 1000; private View mLeftfoot; private Animation mFootAnim;   public void onCreate(Bundle bundle) {     ...     mHandler = new Handler(); //.os package class when importing     mLeftfoot = findViewById(R.id.leftfoot);     mFootAnim = AnimationUtils.loadAnimation( this , R.anim.foot);     stepRecursive(); }   private void stepRecursive() {      mHandler.postDelayed( new Runnable() {          @Override          public void run() {              mLeftFoot.startAnimation(mFootAnim );              stepRecursive();          }      }, mInterval); }

/res/anim/foot.xml

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<?xml version= "1.0" encoding= "utf-8" ?> <set xmlns:android= "" >      <translate android:fromYDelta= "0" android:toYDelta= "-15" android:duration= "400" />      <alpha android:fromAlpha= "1.0" android:toAlpha= "0" android:duration= "400" /> </set>

这是我认为最直接的解决办法，当然，你可以针对特定的需要，再完善以上的代码。