如何维护适配器类中recyclerview项目的可见性答案

【问题标题】：how to maintain Visibllity of recyclerview item in adapter class如何维护适配器类中recyclerview项目的可见性
【发布时间】：2019-01-15 14:08:06
【问题描述】：

我的Adapter 中有一个layout，如下所示：

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:card_view="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#FFFFFF">

        <android.support.v7.widget.CardView
            android:id="@+id/cardVisibleLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/txtCategoryNameTop"
            card_view:cardElevation="2dp">

            <LinearLayout
                android:id="@+id/lnVisibleLayout"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="horizontal">

                <com.joanzapata.iconify.widget.IconTextView
                    android:id="@+id/itxtArrow"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:background="@null"
                    android:gravity="center"
                    android:text="@string/fa_chevron_down"
                    android:textColor="@color/orangePeel" />
                <TextView
                    android:id="@+id/txtConnectToTeacher"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_gravity="center"
                    android:layout_weight="1.3"
                    android:gravity="center"
                    android:text="@string/contact_teacher" />
                <RelativeLayout
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_gravity="right"
                    android:layout_marginBottom="5dp"
                    android:layout_marginLeft="10dp"
                    android:layout_marginTop="5dp"
                    android:layout_weight="3.7"
                    android:gravity="right"
                    android:orientation="vertical">

                    <TextView
                        android:id="@+id/txtCourseName"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:layout_alignParentRight="true"
                        android:layout_marginRight="10dp"
                        android:layout_marginTop="10dp" />

                    <TextView
                        android:id="@+id/txtTeacherName"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:layout_alignParentRight="true"
                        android:layout_below="@+id/txtCourseName"
                        android:layout_marginRight="10dp"
                        android:layout_marginTop="10dp" />
                </RelativeLayout>
            </LinearLayout>
        </android.support.v7.widget.CardView>

        <RelativeLayout
            android:id="@+id/rlInvisibleLayout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_below="@+id/cardVisibleLayout"
            android:animateLayoutChanges="true"
            android:background="#E0E0E0"
            android:visibility="gone">

            <RelativeLayout
                android:id="@+id/rlLessonLink"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_alignParentRight="true"
                android:layout_marginRight="15dp">

                <ImageView
                    android:id="@+id/imgLessonLink"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentRight="true"
                    android:layout_centerVertical="true"
                    android:layout_marginLeft="5dp"
                    app:srcCompat="@drawable/ic_circle" />

                <TextView
                    android:id="@+id/txtLessonLink"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_centerVertical="true"
                    android:layout_toLeftOf="@+id/imgLessonLink"
                    android:text="@string/lesson_link"
                    android:textColor="@color/black" />
            </RelativeLayout>
        </RelativeLayout>
    </RelativeLayout>

我是visible/goneRelativeLayout，这个ID是rlInvisibleLayout，但是当我滚动RecyclerView时我把它弄丢了。

如下：

@Override
public void onBindViewHolder(@NonNull final ViewHolder viewHolder, int position) {
.....
        viewHolder.cardVisibleLayout.setOnClickListener(view -> {
            if (viewHolder.rlInvisibleLayout.getVisibility() == View.VISIBLE) {
                viewHolder.rlInvisibleLayout.setVisibility(View.GONE);
                viewHolder.iconTextView.setText(R.string.fa_chevron_down);
            } else {
                viewHolder.rlInvisibleLayout.setVisibility(View.VISIBLE);
                viewHolder.iconTextView.setText(R.string.fa_chevron_up);
            }
        });
....
}

【问题讨论】：

这是因为RecyclerView被称为RecyclerView？问了很多次
记住位置状态并在onBindViewHolder中恢复（不在OnClickListener中）

标签： android android-layout android-recyclerview android-adapter android-relativelayout

【解决方案1】：

试试这个

像这样在POJO / DataModelClass 中添加boolean 标志

public class Pojo
{               
    boolean isOpen;    

    public boolean isOpen() {
        return isOpen;
    }

    public void setOpen(boolean open) {
        isOpen = open;
    }
}

当用户点击cardVisibleLayout 时，你必须维护boolean 标志

示例代码

@Override
    public void onBindViewHolder(@NonNull ViewHolder viewHolder, int position) {

        // check here the flag and maintain visibility of item based on flag
        if (arrayList.get(position).isOpen()){
            viewHolder.rlInvisibleLayout.setVisibility(View.VISIBLE);
        }else {
            viewHolder.rlInvisibleLayout.setVisibility(View.GONE);

        }

        viewHolder.cardVisibleLayout.setOnClickListener(view -> {

            if (viewHolder.rlInvisibleLayout.getVisibility() == View.VISIBLE) {
                viewHolder.rlInvisibleLayout.setVisibility(View.GONE);
                viewHolder.iconTextView.setText(R.string.fa_chevron_down);
                arrayList.get(position).setOpen(false);// set flag false when you hide the item
            } else {
                arrayList.get(position).setOpen(true);// set flag true when you show the item
                viewHolder.rlInvisibleLayout.setVisibility(View.VISIBLE);
                viewHolder.iconTextView.setText(R.string.fa_chevron_up);
            }
        });

【讨论】：