Question

所以我的问题是：当我向Recycler View添加许多项目时，下面的按钮必须添加更多项目，因为他被回收者从屏幕上扯下来而消失。 before add和after。没有按钮：/

这是xml代码：

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:fab="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".AddActivityFormEvent">


    <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:inputType="date"
    android:ems="14"
    android:id="@+id/dateField"
    android:singleLine="true"
    android:hint="@string/data"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:drawableLeft="@drawable/ic_today"
    android:onClick="showDatePickerDialog"

    />

    <Button

    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="time"
    android:singleLine="true"
    android:hint="@string/czas"
    android:id="@+id/timeField"
    android:layout_alignTop="@+id/dateField"
    android:layout_toRightOf="@+id/dateField"
    android:layout_toEndOf="@+id/dateField"
    android:drawableLeft="@drawable/ic_time"
    android:onClick="showTimePickerDialog"/>

    <RelativeLayout
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:id="@+id/relativeLayout"
    android:layout_below="@+id/dateField">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/linearLayout"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        >


        <android.support.v7.widget.RecyclerView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/activityRecyclerView"
            android:elevation="15dp"
            android:layout_below="@+id/relativeLayout"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true">

        </android.support.v7.widget.RecyclerView>

    </LinearLayout>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/addActivityEvent"
        android:text="Dodaj aktywność"

        android:layout_gravity="bottom"
        android:layout_below="@+id/linearLayout"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />
    </RelativeLayout>

    <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="New Button"
    android:id="@+id/testButton"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true" />

    </RelativeLayout>

顺便问一下，如何获得视图持有者的实际位置？我问，因为当我第一次删除项目时，它返回正确的索引，但每次下一次它都是一次，例如当我删除第一项（索引0）时它返回1 这是一个带有视图持有者的适配器：

public class ActivityFormEventAdapter extends RecyclerView.Adapter<ActivityFormEventAdapter.ActivityFormEventViewHolder>{
ArrayList<ActivityFormEvent> adapter_list = new ArrayList<>();
AddActivityFormEvent addActivityFormEvent;

private static Button button;

Context ctx;
public ActivityFormEventAdapter(ArrayList<ActivityFormEvent> adapter_list,Context ctx){
    this.adapter_list=adapter_list;
    this.ctx=ctx;
    addActivityFormEvent= (AddActivityFormEvent) ctx;
    button= (Button) addActivityFormEvent.findViewById(R.id.testButton);
}

public ActivityFormEventViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_form_event_card,parent,false);
    ActivityFormEventViewHolder activityFormEventViewHolder = new ActivityFormEventViewHolder(view,addActivityFormEvent);
    return activityFormEventViewHolder;
}

@Override
public void onBindViewHolder(ActivityFormEventViewHolder holder, final int position) {
    holder.activityName.setText(adapter_list.get(position).getActivityForm().getName());
    holder.duration.setText(adapter_list.get(position).getTime());
    holder.burnedKcalPerHour.setText(adapter_list.get(position).getActivityForm().getBurnedKcalPerHour());
    holder.burnedKcal.setText(adapter_list.get(position).getBuriedKcal());

    holder.deleteButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            adapter_list.remove(position);
            notifyItemRemoved(position);
        }
    });
}

@Override
public int getItemCount() {
    return adapter_list.size();
}

public static class ActivityFormEventViewHolder extends RecyclerView.ViewHolder{
    AddActivityFormEvent addActivityFormEvent;
    EditText activityName;
    EditText duration;
    EditText burnedKcalPerHour;
    EditText burnedKcal;
    ImageButton deleteButton;

    public ActivityFormEventViewHolder(View itemView,AddActivityFormEvent addActivityFormEvent) {
        super(itemView);
        activityName = (EditText) itemView.findViewById(R.id.activityName);
        duration = (EditText) itemView.findViewById(R.id.duration);
        burnedKcalPerHour = (EditText) itemView.findViewById(R.id.burnedKcalPerHour);
        burnedKcal = (EditText) itemView.findViewById(R.id.kcalExercise);
        deleteButton = (ImageButton) itemView.findViewById(R.id.deleteButton);
        this.addActivityFormEvent = addActivityFormEvent;
    }
}
}

Answer 1

好的尝试这个，这里底视图必须有最小高度=连接的Buttom的高度，并且它的高度必须以编程方式设置为所有视图的高度 - recyclerview内容高度。尝试更改底部视图的高度以查看预览中的差异。

<RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/relativeLayout"
        android:layout_below="@+id/dateField">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="100dp"
            android:id="@+id/linearLayout"
            android:layout_above="@+id/bottom_space_holder"
            android:layout_alignParentTop="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true">
            <android.support.v7.widget.RecyclerView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:id="@+id/activityRecyclerView"
                android:elevation="15dp"
                android:layout_alignParentLeft="true"
                android:layout_alignParentStart="true">
            </android.support.v7.widget.RecyclerView>

        </LinearLayout>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/addActivityEvent"
            android:text="Dodaj aktywność"
            android:layout_alignParentLeft="true"
            android:layout_below="@+id/linearLayout"
            android:layout_alignParentStart="true" />

        <View
            android:layout_width="match_parent"
            android:layout_height="48dp"
            android:id="@+id/bottom_space_holder"
            android:text="Dodaj aktywność"
            android:layout_alignParentBottom="true"/>
    </RelativeLayout>

Answer 2

这是因为您使用Button将RecyclerView置于layout_below下方，RecyclerView的高度设置为wrap_content。这意味着，当RecyclerView的内容超出屏幕高度后，Button将从屏幕上掉落，因为它位于RecyclerView下方。

要解决此问题，您应该将Button与父母的底部对齐（使用layout_alignParentBottom）并在按钮上方布置RecyclerView（使用layout_above和{{ 1}}），这样layout_alignParentTop将始终放置在屏幕底部并显示。

被回收者视图按钮和notifyItemRemoved

2 个答案: