如图要实现点击+号时，出现popwindow：

222.png

//anchor锚点view
private void showSelectDialog(View anchor) {
        View outerView = LayoutInflater.from(this).inflate(R.layout.dialog_chat, null);
//1.这里使用WRAP_CONTENT时可以根据布局大小来灵活掌握
        PopupWindow popupWindow = new PopupWindow(outerView,ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT);
        popupWindow.setFocusable(true);
        popupWindow.setOutsideTouchable(true);
        popupWindow.setOnDismissListener(() -> {
            Utils.changeWindowAlpha(1f, this);
        });
        
        Utils.changeWindowAlpha(0.7f, this);
        popupWindow.showAsDropDown(anchor, 0, 0, Gravity.END);
    }
/**
     * 改变当前window的透明度
     * @param alpha
     * @param context
     */
    public static void changeWindowAlpha(float alpha, Context context) {
        WindowManager.LayoutParams params = ((Activity) context).getWindow().getAttributes();
        params.alpha = alpha;
        ((Activity) context).getWindow().setAttributes(params);
        // 此方法用来设置浮动层，防止部分手机变暗无效
        //((Activity) mContext).getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
    }

布局文件：R.layout.dialog_chat

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
<!--2.在最外层LinearLayout设置精确的宽高值是无效的,所以里面需要再包裹一层-->
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">
<!--3.此处的宽高才是真正在屏幕上显示的大小，具体为图中红点的2和3-->
    <LinearLayout
        android:layout_width="@dimen/dp_120"
        android:layout_height="@dimen/dp_120"
        android:paddingStart="@dimen/dp_10"
<!--4.此处的marginEnd才是真正距离屏幕右侧的大小，具体为图中红点的1-->
        android:layout_marginEnd="@dimen/dp_20"
        android:background="@drawable/bg_chat_main"
        android:orientation="vertical">
        <TextView
            android:id="@+id/tv_my_card"
            android:layout_width="wrap_content"
            android:layout_marginTop="@dimen/dp_25"
            android:textColor="@color/color_333333"
            android:textSize="@dimen/sp_16"
            android:drawablePadding="@dimen/dp_5"
            android:drawableStart="@drawable/icon_my_card"
            android:layout_height="wrap_content"
            android:text="@string/wo_de_ming_pian"/>
        <TextView
            android:id="@+id/tv_scan"
            android:layout_width="wrap_content"
            android:layout_marginTop="@dimen/dp_25"
            android:textColor="@color/color_333333"
            android:textSize="@dimen/sp_16"
            android:drawablePadding="@dimen/dp_5"
            android:drawableStart="@drawable/icon_scan"
            android:layout_height="wrap_content"
            android:text="@string/sao_yi_sao"/>
    </LinearLayout>
</LinearLayout>

注意代码中1,2,3,4的注释，助你灵活掌握popwindow的大小和间距。

如果需要改成自定义PopupWindow形式如下：

public class CardFilterPop extends PopupWindow {
    private Context mContext;
    private View outerView;
    private TextView tv_my_card,tv_scan;
    private View anchor;//描点view
    private PopWindowOnClickListener mOnClickListener;

    public interface PopWindowOnClickListener {
        void onResetClick();
        void onSureClick();
    }
    public CardFilterPop(Context context,View anchor, List<String> data,PopWindowOnClickListener listener){
        mContext=context;
        this.anchor=anchor;
        mOnClickListener=listener;
        setWidth(ViewGroup.LayoutParams.WRAP_CONTENT);
        setHeight(ViewGroup.LayoutParams.WRAP_CONTENT);
        setFocusable(true);
        setOutsideTouchable(true);
        setOnDismissListener(() -> changeWindowAlpha(1f, mContext));
        outerView = LayoutInflater.from(context).inflate(R.layout.dialog_chat, null);
        initViews(data);
        setContentView(outerView);
    }
    private void initViews(List<String> data){
        tv_my_card=outerView.findViewById(tv_my_card);
        tv_scan=outerView.findViewById(R.id.tv_scan);
        //省略一些业务代码
        tv_my_card.setOnClickListener(view -> {
            if(mOnClickListener!=null){
                mOnClickListener.onResetClick();
            }
        });
        tv_scan.setOnClickListener(view -> {
            if(mOnClickListener!=null){
                mOnClickListener.onSureClick();
            }
        });
    }
    public void showPop(){
        //changeWindowAlpha(0.7f, mContext);
        showAsDropDown(anchor, 0, 0, Gravity.END);
    }
    /**
     * 改变当前window的透明度
     * @param alpha
     * @param context
     */
    private void changeWindowAlpha(float alpha, Context context) {
        WindowManager.LayoutParams params = ((Activity) context).getWindow().getAttributes();
        params.alpha = alpha;
        ((Activity) context).getWindow().setAttributes(params);
    }
}

调用时

private CardFilterPop cardFilterPop;
if (cardFilterPop == null) {
                cardFilterPop=new CardFilterPop(getContext(), ll_filter, data, new CardFilterPop.PopWindowOnClickListener() {
                    @Override
                    public void onResetClick() {

                    }

                    @Override
                    public void onSureClick() {

                    }
                });
            }
            cardFilterPop.showPop();