android - 一旦顶部的回收 View 变大，如何制作固定在布局滚动底部的按钮

Question

我有一个非常基本但困难的问题，我有一个按钮固定在 View 底部，但在 recyclerview 容器下方。一旦容器大小增加，我希望按钮位于 recyclerview(可滚动)下方，而不是固定在 View 底部。有没有办法实现这一点？

我在网上查找了一些想法，但还没有找到任何类似的想法。

我基本上都在用

 <?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white"
    android:clickable="false">

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/cl_root_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clipChildren="false">

        <LinearLayout
            android:id="@+id/activity_g"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <android.support.design.widget.AppBarLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:elevation="0dp">


                <android.support.v7.widget.Toolbar
                    android:id="@+id/toolbar"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@color/white"
                    app:subtitleTextColor="@color/white"
                    app:titleTextAppearance="@style/Toolbar.TitleText"
                    app:titleTextColor="@color/white">


                    <TextView
                        android:id="@+id/nav_back_btn"
                        style="@style/Body1RegLeftBlack"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginTop="20dp"
                        android:layout_marginStart="@dimen/activity_horizontal_margin"
                        android:gravity="center_horizontal"
                        android:background="@drawable/ic_backarrow" />

                    <TextView
                        android:id="@+id/g_main_title"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginStart="18dp"
                        android:layout_marginTop="15dp"
                        android:letterSpacing="0.01"
                        android:gravity="center_horizontal"
                        android:text="@string/g"
                        android:textAppearance="@style/TextAppearance.Text.Roboto.Medium"
                        android:textColor="#de000000"
                        android:textSize="20sp"
                        android:textStyle="normal"

                        />

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


            </android.support.design.widget.AppBarLayout>

            <android.support.v4.widget.NestedScrollView
                android:id="@+id/info_scrollview"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <LinearLayout
                    android:id="@+id/infoContainer"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@color/white"
                    android:clickable="false"
                    android:orientation="vertical">

                    <RelativeLayout
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginTop="30dp">

                        <TextView
                            android:id="@+id/info_location"
                            style="@style/Headline2LeftBlack"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_marginStart="@dimen/activity_horizontal_margin"
                            android:textAppearance="@style/TextAppearance.Text.Chronicle"
                            android:textSize="28sp"
                            tools:text="@string/five_thirty_fifth_ave" />

                        <TextView
                            style="@style/Body1RegRightRed"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_alignBaseline="@+id/info_location"
                            android:layout_alignParentEnd="true"
                            android:layout_marginEnd="@dimen/activity_horizontal_margin"
                            android:layout_toEndOf="@+id/info_location"
                            android:text="@string/location_change"
                            android:textAppearance="@style/TextAppearance.Text.Roboto.Regular"
                            android:visibility="gone" />
                    </RelativeLayout>

                    <LinearLayout
                        android:layout_width="match_parent"
                        android:layout_height="48dp"
                        android:layout_marginTop="44dp"
                        android:gravity="center_vertical"
                        android:weightSum="2">

                        <TextView
                            style="@style/Body1RegLeftBlack"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_marginStart="16dp"
                            android:layout_weight="1"
                            android:id="@+id/g_start_date"
                            android:textAppearance="@style/TextAppearance.Text.Roboto.Regular"
                            android:text="@string/g_start_date" />

                        <TextView
                            style="@style/Body1RegRightBlack"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_marginEnd="16dp"
                            android:layout_weight="1"
                            android:id="@+id/g_start_time"
                            android:textAppearance="@style/TextAppearance.Text.Roboto.Regular"
                            android:text="@string/g_start_time" />
                    </LinearLayout>

                    <View
                        android:layout_width="match_parent"
                        android:layout_height="1dp"
                        android:background="@color/registerUserSeparatorColor" />

                    <LinearLayout
                        android:layout_width="match_parent"
                        android:layout_height="48dp"
                        android:gravity="center_vertical"
                        android:weightSum="2">

                        <TextView
                            style="@style/Body1RegLeftBlack"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_marginStart="16dp"
                            android:layout_weight="1"
                            android:id="@+id/g_end_date"
                            android:textAppearance="@style/TextAppearance.Text.Roboto.Regular"
                            android:visibility="invisible"
                            android:text="@string/g_end_date" />

                        <TextView
                            style="@style/Body1RegRightBlack"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_marginEnd="16dp"
                            android:layout_weight="1"
                            android:id="@+id/g_end_time"
                            android:textAppearance="@style/TextAppearance.Text.Roboto.Regular"
                            android:text="@string/g_end_time" />
                    </LinearLayout>

                    <View
                        android:layout_width="match_parent"
                        android:layout_height="1dp"
                        android:background="@color/registerUserSeparatorColor" />


                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginStart="16dp"
                        android:layout_marginTop="28dp"
                        android:letterSpacing="0.01"
                        android:lineSpacingExtra="4sp"
                        android:paddingTop="30dp"
                        android:textAppearance="@style/TextAppearance.Text.Roboto.Medium"
                        android:textColor="@color/black"
                        android:textSize="20sp"
                        android:textStyle="normal"
                        android:text="@string/g" />


                    <android.support.v7.widget.RecyclerView
                        android:id="@+id/g_item_list"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:overScrollMode="never"
                        android:divider="@null"
                        tools:listitem="@layout/item_g"/>

                    <TextView
                        style="@style/Body1RegLeftRed"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginStart="16sp"
                        android:layout_marginTop="20dp"
                        android:id="@+id/add_g"
                        android:lineHeight="22sp"
                        android:text="@string/add_g"
                        android:textSize="16sp" />

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginStart="16dp"
                        android:layout_marginTop="58dp"
                        android:letterSpacing="0.01"
                        android:lineSpacingExtra="4sp"
                        android:visibility="invisible"
                        android:textAppearance="@style/TextAppearance.Text.Roboto.Medium"
                        android:textColor="@color/black"
                        android:textSize="20sp"
                        android:textStyle="normal"
                        android:text="@string/arrival_notifications" />

                    <RelativeLayout
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:visibility="gone"
                        android:id="@+id/text_message_container"
                        android:layout_marginStart="16dp">

                        <TextView
                            android:id="@+id/text_message"
                            style="@style/Body1RegLeftBlack"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_marginTop="11dp"
                            android:textAppearance="@style/TextAppearance.Text.Roboto.Regular"
                            android:text="@string/text_message" />

                        <TextView
                            style="@style/Body2RegLeftGrey"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_below="@+id/text_message"
                            android:layout_marginTop="2dp"
                            android:id="@+id/tap_phone_number_text"
                            android:textAppearance="@style/TextAppearance.Text.Roboto.Regular"
                            android:text="@string/tap_to_add_a_phone_number" />

                        <android.support.v7.widget.SwitchCompat
                            android:id="@+id/text_message_switch"
                            style="@style/Color1SwitchStyle"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_alignParentEnd="true"
                            android:layout_centerVertical="true"
                            android:layout_marginEnd="16dp" />
                    </RelativeLayout>
                    <View
                        android:layout_width="match_parent"
                        android:layout_height="1dp"
                        android:layout_marginStart="16dp"
                        android:visibility="gone"
                        android:layout_marginTop="11dp"
                        android:background="@color/settingsSeparatorLineColor" />


                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:textSize="16sp"
                        android:layout_marginTop="100dp"
                        android:textAppearance="@style/TextAppearance.Text.Roboto.Medium"
                        android:textStyle="normal"

                        android:letterSpacing="0.07"
                        android:lineSpacingExtra="0sp"
                        android:layout_gravity="center"
                        android:layout_marginBottom="30dp"
                        android:id="@+id/submit_btn"
                        android:text="@string/submit_list"
                        />

                </LinearLayout>
            </android.support.v4.widget.NestedScrollView>
        </LinearLayout>
    </android.support.design.widget.CoordinatorLayout>
</android.support.design.widget.CoordinatorLayout>

上面的问题是，submit_list btn 不会保持固定，如果 recyclerview 增长但 View 中仍有足够的空间可用。

我想让按钮保持固定并且不滚动直到 recyclerview 的大小超出底部的某个限制(在屏幕上不再可见)，之后按钮相对于最后一个项目滚动recyclerview 的，不再与底部对齐。有什么想法吗？

举个形象的例子:

如您所见，初始屏幕的提交按钮与底部对齐，其余内容就位。当我添加更多用户时:

它仍然停留在底部，因为 recyclerview 项目仍在屏幕内 现在，只要我再添加一项，列表就会向上滚动:

正如我所看到的，我希望它位于 recyclerview 下方，而不是固定在屏幕底部(上面的屏幕截图来自它工作的 ios)，想知道我们是否可以为 android 做同样的事情？

Answer 1

您可以使用 ConstraintLayout

实现此目的

示例代码

layout file

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">


    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/myRecyclerView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        app:layout_constraintBottom_toTopOf="@+id/btnBottom"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHeight_default="wrap"
        app:layout_constraintHorizontal_chainStyle="packed"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintStart_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/btnBottom"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="12dp"
        android:layout_marginRight="20dp"
        android:padding="12dp"
        android:text="Continue"
        android:textAllCaps="false"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        android:textColor="@android:color/white"
        app:backgroundTint="@color/colorPrimary" />

</androidx.constraintlayout.widget.ConstraintLayout>

Activity code

public class MainActivity extends AppCompatActivity {

    RecyclerView myRecyclerView;
    ArrayList<String> arrayList = new ArrayList<>();
    DataAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        myRecyclerView = findViewById(R.id.myRecyclerView);
        myRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        myRecyclerView.setHasFixedSize(true);

        addDataToList();

        adapter = new DataAdapter(this, arrayList);
        myRecyclerView.setAdapter(adapter);

    }

    private void addDataToList() {
        for (int i = 0; i < 5; i++) {
            arrayList.add("NILU_PILU :-> " + i);
        }
    }

}

DataAdapter class

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.ArrayList;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

public class DataAdapter extends RecyclerView.Adapter<DataAdapter.ViewHolder> {

    ArrayList<String> arrayList = new ArrayList<>();
    private Context mContext;

    public DataAdapter(Context mContext, ArrayList<String> arrayList) {
        this.mContext = mContext;
        this.arrayList = arrayList;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(mContext).inflate(R.layout.aaa, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        holder.tvText.setText(arrayList.get(position));
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {
        TextView tvText;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            tvText = itemView.findViewById(R.id.tvText);
        }
    }
}

OUTPUTS