用androidx实现Viewpager中的点设计

implementation 'androidx.viewpager2:viewpager2:1.1.0-alpha01'

<androidx.viewpager2.widget.ViewPager2
    android:id="@+id/viewPager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<LinearLayout
    android:id="@+id/dotsLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom"
    android:gravity="center"
    android:orientation="horizontal" />

public class MyPagerAdapter extends RecyclerView.Adapter<MyPagerAdapter.ViewHolder> {
    private List<PageData> pageDataList;

    public MyPagerAdapter(List<PageData> pageDataList) {
        this.pageDataList = pageDataList;
    }

    // 实现必要的方法
    // ...

    class ViewHolder extends RecyclerView.ViewHolder {
        TextView textView;

        ViewHolder(View itemView) {
            super(itemView);
            textView = itemView.findViewById(R.id.textView);
        }
    }
}

ViewPager2 viewPager = findViewById(R.id.viewPager);
LinearLayout dotsLayout = findViewById(R.id.dotsLayout);

MyPagerAdapter adapter = new MyPagerAdapter(pageDataList);
viewPager.setAdapter(adapter);

// 创建点的指示器
for (int i = 0; i < pageDataList.size(); i++) {
    ImageView dot = new ImageView(this);
    dot.setImageDrawable(ContextCompat.getDrawable(this, R.drawable.ic_dot));
    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.WRAP_CONTENT,
            LinearLayout.LayoutParams.WRAP_CONTENT
    );
    params.setMargins(8, 0, 8, 0);
    dotsLayout.addView(dot, params);
}

viewPager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
    @Override
    public void onPageSelected(int position) {
        super.onPageSelected(position);
        // 更新点的状态
        for (int i = 0; i < dotsLayout.getChildCount(); i++) {
            ImageView dot = (ImageView) dotsLayout.getChildAt(i);
            dot.setImageDrawable(ContextCompat.getDrawable(MainActivity.this,
                    i == position ? R.drawable.ic_dot_selected : R.drawable.ic_dot));
        }
    }
});