<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <RelativeLayout        android:layout_width="match_parent"        android:layout_height="200dp">        <android.support.v4.view.ViewPager            android:id="@+id/viewPager"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:layout_alignParentLeft="true"            android:layout_alignParentTop="true" />        <LinearLayout            android:id="@+id/dotLayout"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:layout_alignParentBottom="true"            android:layout_centerHorizontal="true"            android:layout_marginBottom="20dp"            android:gravity="center"            android:orientation="horizontal" />    </RelativeLayout></RelativeLayout>

<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_enabled="true">        <shape android:shape="oval">            <size android:height="10dp" android:width="10dp"></size>            <solid android:color="#aa000000"></solid>        </shape>    </item>    <item android:state_enabled="false">        <shape android:shape="oval">            <size android:height="10dp" android:width="10dp"></size>            <solid android:color="#aaffffff"></solid>        </shape>    </item></selector>

public class MainActivity extends AppCompatActivity {    private List<ImageView> list;    private LinearLayout dotLayout;    private int prePosition;    private ViewPager viewPager;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initData();        initView();        //开启一个新线程，实现ViewPager的自动滚动        new Thread(new Runnable() {            @Override            public void run() {                while (true) {                    try {                        Thread.sleep(3000);                    } catch (InterruptedException e) {                        e.printStackTrace();                    }                    //runOnUiThread中的代码运行在主线程中                    runOnUiThread(new Runnable() {                        @Override                        public void run() {                            viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);                        }                    });                }            }        }).start();    }    private void initView() {        viewPager = (ViewPager) findViewById(R.id.viewPager);        //构造适配器        MyAdapter adapter = new MyAdapter(list);        //设置Adapter        viewPager.setAdapter(adapter);        //设置ViewPager预加载的页数//        viewPager.setOffscreenPageLimit(2);        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {            //ViewPager滑动过程中调用            @Override            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {            }            //ViewPager新页面确定后调用            @Override            public void onPageSelected(int position) {                //设置前一个View为白色                dotLayout.getChildAt(prePosition).setEnabled(false);                //设置当前View为红色                dotLayout.getChildAt(position % list.size()).setEnabled(true);                //将当前位置赋给prePosition                prePosition = position % list.size();            }            //ViewPager滑动状态改变后调用            //0--静止状态            //1--手在拖动            //2--手松开后自动滑动            @Override            public void onPageScrollStateChanged(int state) {            }        });        //设置ViewPager的初始item        viewPager.setCurrentItem(Integer.MAX_VALUE / 2 - 3);    }    /**     * 构造数据源     */    private void initData() {        dotLayout = (LinearLayout) findViewById(R.id.dotLayout);        list = new ArrayList<>();        int[] imgs = new int[]{R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d, R.drawable.e};        for (int img : imgs) {            //使用Java代码创建一个ImageView            ImageView imageView = new ImageView(this);            //设置图片以及ScaleType属性            imageView.setImageResource(img);            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);            list.add(imageView);            //创建一个View对象            View view = new View(this);            //设置View的宽和高            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams((int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 8, getResources().getDisplayMetrics()), (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 8, getResources().getDisplayMetrics()));            //设置View左边距，避免View连在一起            params.leftMargin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 12, getResources().getDisplayMetrics());            view.setLayoutParams(params);            //设置背景颜色，背景使用selector，可使View在不同状态显示不同颜色            view.setBackgroundResource(R.drawable.dot_radiobutton_style);            //默认状态下View的Enable属性为false（View全为白色）            view.setEnabled(false);            //将View添加进LinearLayout中            dotLayout.addView(view);        }        //第一个View默认为红色        dotLayout.getChildAt(0).setEnabled(true);    }}