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废话不多说，直接上代码**************************指示器的工具类public class PageIndicator implements ViewPager.OnPageChangeListener {    private int mPageCount;//页数    private List
   
     mImgList;//保存img总个数    private int img_select;    private int img_unSelect;    public PageIndicator(Context context, LinearLayout linearLayout, int pageCount) {        this.mPageCount = pageCount;        mImgList = new ArrayList<>();        img_select = R.drawable.dot_select;        img_unSelect = R.drawable.dot_unselect;        final int imgSize = 25;        for (int i = 0; i < mPageCount; i++) {            ImageView imageView = new ImageView(context);            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(new ViewGroup.LayoutParams(                    ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));            //为小圆点左右添加间距            params.leftMargin = 10;            params.rightMargin = 10;            //给小圆点一个默认大小            params.height = imgSize;            params.width = imgSize;            if (i == 0) {                imageView.setBackgroundResource(img_select);            } else {                imageView.setBackgroundResource(img_unSelect);            }            //为LinearLayout添加ImageView            linearLayout.addView(imageView, params);            mImgList.add(imageView);        }    }    @Override    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}    @Override    public void onPageSelected(int position) {        for (int i = 0; i < mPageCount; i++) {            //选中的页面改变小圆点为选中状态，反之为未选中            if ((position % mPageCount) == i) {                (mImgList.get(i)).setBackgroundResource(img_select);            } else {                (mImgList.get(i)).setBackgroundResource(img_unSelect);            }        }    }    @Override    public void onPageScrollStateChanged(int state) {}}
   

小圆点选中 dot_select

小圆点未选中

主要实现方法：

public class MainActivity extends AppCompatActivity {    private ViewPager vp_loop_advertisement;    private LinearLayout dot_horizontal;    private ArrayList
   
     imgList;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        int[] img = new int[]{R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.c};//图片自己找        imgList = new ArrayList<>();        for (int i = 0; i < img.length; i++) {            ImageView imageView = new ImageView(this);            imageView.setImageResource(img[i]);            imgList.add(imageView);        }        dot_horizontal = (LinearLayout) findViewById(R.id.dot_horizontal);        vp_loop_advertisement = (ViewPager) findViewById(R.id.vp_loop_advertisement);        vp_loop_advertisement.setAdapter(new MyAdapter());        vp_loop_advertisement.addOnPageChangeListener(new PageIndicator(this, dot_horizontal, img.length));    }    private class MyAdapter extends PagerAdapter {        @Override        public int getCount() {            return imgList.size();        }        @Override        public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {            return view == o;        }        @NonNull        @Override        public Object instantiateItem(@NonNull ViewGroup container, int position) {            ImageView imageView = imgList.get(position % imgList.size());            container.addView(imageView);            return imageView;        }        @Override        public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {            container.removeView((View) object);        }    }}
   

对应的xml文件activity_main

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