如何使用RecyclerView构建Horizo​​ntal ListView？

Question

我需要在我的Android应用程序中实现水平列表视图.我做了一些研究并遇到了如何在Android中制作水平ListView？和Android中的水平ListView？然而,这些问题是在Recyclerview发布之前提出的.现在使用Recyclerview有更好的方法来实现吗？

Answer 1

现在使用Recyclerview有更好的方法来实现吗？

是.

使用a时RecyclerView,需要指定LayoutManager负责在视图中布置每个项目的a.在LinearLayoutManager允许您指定的方向,就像一个正常的LinearLayout会.

要创建水平列表RecyclerView,您可以执行以下操作:

LinearLayoutManager layoutManager
    = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);

RecyclerView myList = (RecyclerView) findViewById(R.id.my_recycler_view);
myList.setLayoutManager(layoutManager);

Answer 2

 <android.support.v7.widget.RecyclerView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layoutManager="android.support.v7.widget.LinearLayoutManager" />

Answer 3

完整的例子

垂直RecyclerView和水平之间唯一真正的区别在于你如何设置LinearLayoutManager.这是代码片段.完整的例子如下.

LinearLayoutManager horizontalLayoutManagaer = new LinearLayoutManager(MainActivity.this, LinearLayoutManager.HORIZONTAL, false);
recyclerView.setLayoutManager(horizontalLayoutManagaer);

这个更完整的例子是在我的垂直RecyclerView答案之后建模的.

更新Gradle依赖项

确保您的app gradle.build文件中包含以下依赖项:

implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support:recyclerview-v7:27.1.1'

您可以更新的版本号无论是最新的.

创建活动布局

添加RecyclerView到您的xml布局.

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rvAnimals"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</RelativeLayout>

创建项目布局

我们的每个项目RecyclerView都将有一个彩色View的a TextView.创建一个新的布局资源文件.

recyclerview_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="10dp">

    <View
        android:id="@+id/colorView"
        android:layout_width="100dp"
        android:layout_height="100dp"/>

    <TextView
        android:id="@+id/tvAnimalName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="20sp"/>

</LinearLayout>

创建适配器

将RecyclerView需要一个适配器来填充你的数据在每一行(水平项目)的意见.创建一个新的java文件.

MyRecyclerViewAdapter.java

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

    private List<Integer> mViewColors;
    private List<String> mAnimals;
    private LayoutInflater mInflater;
    private ItemClickListener mClickListener;

    // data is passed into the constructor
    MyRecyclerViewAdapter(Context context, List<Integer> colors, List<String> animals) {
        this.mInflater = LayoutInflater.from(context);
        this.mViewColors = colors;
        this.mAnimals = animals;
    }

    // inflates the row layout from xml when needed
    @Override
    @NonNull
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = mInflater.inflate(R.layout.recyclerview_item, parent, false);
        return new ViewHolder(view);
    }

    // binds the data to the view and textview in each row
    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        int color = mViewColors.get(position);
        String animal = mAnimals.get(position);
        holder.myView.setBackgroundColor(color);
        holder.myTextView.setText(animal);
    }

    // total number of rows
    @Override
    public int getItemCount() {
        return mAnimals.size();
    }

    // stores and recycles views as they are scrolled off screen
    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        View myView;
        TextView myTextView;

        ViewHolder(View itemView) {
            super(itemView);
            myView = itemView.findViewById(R.id.colorView);
            myTextView = itemView.findViewById(R.id.tvAnimalName);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View view) {
            if (mClickListener != null) mClickListener.onItemClick(view, getAdapterPosition());
        }
    }

    // convenience method for getting data at click position
    public String getItem(int id) {
        return mAnimals.get(id);
    }

    // allows clicks events to be caught
    public void setClickListener(ItemClickListener itemClickListener) {
        this.mClickListener = itemClickListener;
    }

    // parent activity will implement this method to respond to click events
    public interface ItemClickListener {
        void onItemClick(View view, int position);
    }
}

笔记

• 虽然不是绝对必要,但我包含了监听项目点击事件的功能.这在旧版本中是可用的ListViews并且是常见的需求.如果您不需要,可以删除此代码.

在Activity中初始化RecyclerView

将以下代码添加到主活动中.

MainActivity.java

public class MainActivity extends AppCompatActivity implements MyRecyclerViewAdapter.ItemClickListener {

    private MyRecyclerViewAdapter adapter;

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

        // data to populate the RecyclerView with
        ArrayList<Integer> viewColors = new ArrayList<>();
        viewColors.add(Color.BLUE);
        viewColors.add(Color.YELLOW);
        viewColors.add(Color.MAGENTA);
        viewColors.add(Color.RED);
        viewColors.add(Color.BLACK);

        ArrayList<String> animalNames = new ArrayList<>();
        animalNames.add("Horse");
        animalNames.add("Cow");
        animalNames.add("Camel");
        animalNames.add("Sheep");
        animalNames.add("Goat");

        // set up the RecyclerView
        RecyclerView recyclerView = findViewById(R.id.rvAnimals);
        LinearLayoutManager horizontalLayoutManager
                = new LinearLayoutManager(MainActivity.this, LinearLayoutManager.HORIZONTAL, false);
        recyclerView.setLayoutManager(horizontalLayoutManager);
        adapter = new MyRecyclerViewAdapter(this, viewColors, animalNames);
        adapter.setClickListener(this);
        recyclerView.setAdapter(adapter);
    }

    @Override
    public void onItemClick(View view, int position) {
        Toast.makeText(this, "You clicked " + adapter.getItem(position) + " on item position " + position, Toast.LENGTH_SHORT).show();
    }
}

笔记

• 请注意,该活动实现了ItemClickListener我们在适配器中定义的活动.这允许我们处理项目点击事件onItemClick.

成品

而已.您应该能够立即运行项目并获得与顶部图像类似的内容.

笔记

• 我的示例中的彩色视图当然可以替换为真实项目中的图像.
• Vertical RecyclerView例子

Answer 4

如果你想使用RecyclerView同GridLayoutManager,这是实现横向滚动的方式.

recyclerView.setLayoutManager(
new GridLayoutManager(recyclerView.getContext(), rows, GridLayoutManager.HORIZONTAL, false));

Answer 5

您可以从布局文件或 java/kotlin 文件中定义方向和布局管理器

使用XML

<androidx.recyclerview.widget.RecyclerView
        android:id="@+id/my_recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />

爪哇语

LinearLayoutManager layoutManager
= new LinearLayoutManager(requireContext(), LinearLayoutManager.HORIZONTAL, false);

RecyclerView rv= (RecyclerView) findViewById(R.id.my_recyclerView);
rv.setLayoutManager(layoutManager);

在科特林中

val layoutManager
= LinearLayoutManager(requireContext(), LinearLayoutManager.HORIZONTAL, false)
my_recyclerView.layoutManager = layoutManager

Answer 6

尝试构建水平ListView需要花费太多时间.我已经用两种方式解决了这个问题.

1.使用ViewPager,其适配器从PagerAdapter扩展.

2.如上所述使用RecyclerView.需要应用LayoutManager,如下面的代码所示:

LinearLayoutManager layoutManager
    = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);

RecyclerView myList = (RecyclerView) findViewById(R.id.my_recycler_view);
myList.setLayoutManager(layoutManager);

Answer 7

如果您希望使用Horizo​​ntal Recycler View作为ViewPager,那么现在可以LinearSnapHelper在支持库版本24.2.0中添加帮助.

首先将RecyclerView添加到您的Activity/Fragment中

<android.support.v7.widget.RecyclerView
        android:layout_below="@+id/sign_in_button"
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:id="@+id/blog_list"
        android:layout_height="match_parent">
    </android.support.v7.widget.RecyclerView>

在我的情况下,我使用了CardView内部RecyclerView

blog_row.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView 

    xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_margin="15dp"
        android:orientation="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            android:orientation="vertical">

            <com.android.volley.toolbox.NetworkImageView
                android:id="@+id/imageBlogPost"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:adjustViewBounds="true"
                android:paddingBottom="15dp"
                android:src="@drawable/common_google_signin_btn_text_light_normal" />

            <TextView
                android:id="@+id/TitleTextView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
               android:layout_marginBottom="20dp"

                android:text="Post Title Here"
                android:textSize="16sp" />

            <TextView
                android:id="@+id/descriptionTextView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Post Description Here"
                android:paddingBottom="15dp"
                android:textSize="14sp" />
        </LinearLayout>

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

在你的活动/片段中

    private RecyclerView mBlogList;




 LinearLayoutManager layoutManager
                    = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
            mBlogList = (RecyclerView) findViewById(R.id.blog_list);

            mBlogList.setHasFixedSize(true);
            mBlogList.setLayoutManager(layoutManager);

LinearSnapHelper snapHelper = new LinearSnapHelper() {
            @Override
            public int findTargetSnapPosition(RecyclerView.LayoutManager lm, int velocityX, int velocityY) {
                View centerView = findSnapView(lm);
                if (centerView == null)
                    return RecyclerView.NO_POSITION;

                int position = lm.getPosition(centerView);
                int targetPosition = -1;
                if (lm.canScrollHorizontally()) {
                    if (velocityX < 0) {
                        targetPosition = position - 1;
                    } else {
                        targetPosition = position + 1;
                    }
                }

                if (lm.canScrollVertically()) {
                    if (velocityY < 0) {
                        targetPosition = position - 1;
                    } else {
                        targetPosition = position + 1;
                    }
                }

                final int firstItem = 0;
                final int lastItem = lm.getItemCount() - 1;
                targetPosition = Math.min(lastItem, Math.max(targetPosition, firstItem));
                return targetPosition;
            }
        };
        snapHelper.attachToRecyclerView(mBlogList);

最后一步是将适配器设置为RecyclerView

mBlogList.setAdapter(firebaseRecyclerAdapter);

Answer 8

随着 RecyclerView 库的发布，现在您可以轻松对齐与文本绑定的图像列表。您可以使用 LinearLayoutManager 指定您希望将列表定向的方向，垂直或水平，如下所示。

您可以从这篇文章下载完整的工作演示。