我用Android的RecyclerView做过几次物品列表,但这是一个相当复杂的过程。浏览众多在线教程中的一个作品(这个,这个,这个都很好),但我正在寻找一个简单的示例,我可以复制和粘贴来快速启动和运行。只需要以下特性:

垂直布局 每行都有一个单一的TextView 响应点击事件

因为这个愿望我已经许过好几次了,所以我最终决定把答案写在下面,供我和你们将来参考。


当前回答

我很高兴我不是唯一一个认为这些“最小”示例都涉及创建至少4个不同文件来创建一个简单工具的人。

下面是Kotlin中的一个独立活动(基于Saifur Rahman Mohsin的回答),它实现了一个基本的回收器视图:

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.constraintlayout.widget.ConstraintLayout
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView

class ModelDownloaderActivity : AppCompatActivity() {

    val items = (1..50).toList().map { "Item #$it" }
    inner class ItemHolder(view: View, var textField: TextView = view.findViewById(android.R.id.text1)) : RecyclerView.ViewHolder(view)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Create recycler view, or find it in Activity's XML file if you prefer
        val myLayoutResource: Int? = null // Replace with R.layout.activity_model_downloader if you want to use an XML layout with a recycler view in it
        val recyclerView = myLayoutResource?.let {
            setContentView(it)
            findViewById(R.id.modelRecyclerView) // Replace with ID of your recycler view in layout
        } ?: RecyclerView(this).also { setContentView(ConstraintLayout(this).apply { addView(it) }) }

        // Bind controls to it.
        recyclerView.layoutManager = LinearLayoutManager(this)
        recyclerView.adapter = object : RecyclerView.Adapter<ItemHolder>() {
            override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
                ItemHolder(LayoutInflater.from(parent.context).inflate(android.R.layout.simple_list_item_1, parent, false))
            override fun getItemCount() = items.size
            override fun onBindViewHolder(holder: ItemHolder, position: Int) {
                holder.textField.text = items[position]
                holder.textField.setOnClickListener {
                    Toast.makeText(this@ModelDownloaderActivity, "Clicked $position", Toast.LENGTH_SHORT).show()
                }
            }
        }
    }
}

其他回答

您可以使用带有diff utils和过滤器的抽象适配器

SimpleAbstractAdapter.kt

abstract class SimpleAbstractAdapter<T>(private var items: ArrayList<T> = arrayListOf()) : RecyclerView.Adapter<SimpleAbstractAdapter.VH>() {
   protected var listener: OnViewHolderListener<T>? = null
   private val filter = ArrayFilter()
   private val lock = Any()
   protected abstract fun getLayout(): Int
   protected abstract fun bindView(item: T, viewHolder: VH)
   protected abstract fun getDiffCallback(): DiffCallback<T>?
   private var onFilterObjectCallback: OnFilterObjectCallback? = null
   private var constraint: CharSequence? = ""

override fun onBindViewHolder(vh: VH, position: Int) {
    getItem(position)?.let { bindView(it, vh) }
}

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): VH {
    return VH(parent, getLayout())
}

override fun getItemCount(): Int = items.size

protected abstract class DiffCallback<T> : DiffUtil.Callback() {
    private val mOldItems = ArrayList<T>()
    private val mNewItems = ArrayList<T>()

    fun setItems(oldItems: List<T>, newItems: List<T>) {
        mOldItems.clear()
        mOldItems.addAll(oldItems)
        mNewItems.clear()
        mNewItems.addAll(newItems)
    }

    override fun getOldListSize(): Int {
        return mOldItems.size
    }

    override fun getNewListSize(): Int {
        return mNewItems.size
    }

    override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
        return areItemsTheSame(
                mOldItems[oldItemPosition],
                mNewItems[newItemPosition]
        )
    }

    abstract fun areItemsTheSame(oldItem: T, newItem: T): Boolean

    override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
        return areContentsTheSame(
                mOldItems[oldItemPosition],
                mNewItems[newItemPosition]
        )
    }

    abstract fun areContentsTheSame(oldItem: T, newItem: T): Boolean
}

class VH(parent: ViewGroup, @LayoutRes layout: Int) : RecyclerView.ViewHolder(LayoutInflater.from(parent.context).inflate(layout, parent, false))

interface OnViewHolderListener<T> {
    fun onItemClick(position: Int, item: T)
}

fun getItem(position: Int): T? {
    return items.getOrNull(position)
}

fun getItems(): ArrayList<T> {
    return items
}

fun setViewHolderListener(listener: OnViewHolderListener<T>) {
    this.listener = listener
}

fun addAll(list: List<T>) {
    val diffCallback = getDiffCallback()
    when {
        diffCallback != null && !items.isEmpty() -> {
            diffCallback.setItems(items, list)
            val diffResult = DiffUtil.calculateDiff(diffCallback)
            items.clear()
            items.addAll(list)
            diffResult.dispatchUpdatesTo(this)
        }
        diffCallback == null && !items.isEmpty() -> {
            items.clear()
            items.addAll(list)
            notifyDataSetChanged()
        }
        else -> {
            items.addAll(list)
            notifyDataSetChanged()
        }
    }
}

fun add(item: T) {
    items.add(item)
    notifyDataSetChanged()
}

fun add(position:Int, item: T) {
    items.add(position,item)
    notifyItemInserted(position)
}

fun remove(position: Int) {
    items.removeAt(position)
    notifyItemRemoved(position)
}

fun remove(item: T) {
    items.remove(item)
    notifyDataSetChanged()
}

fun clear(notify: Boolean=false) {
    items.clear()
    if (notify) {
        notifyDataSetChanged()
    }
}

fun setFilter(filter: SimpleAdapterFilter<T>): ArrayFilter {
    return this.filter.setFilter(filter)
}

interface SimpleAdapterFilter<T> {
    fun onFilterItem(contains: CharSequence, item: T): Boolean
}

fun convertResultToString(resultValue: Any): CharSequence {
    return filter.convertResultToString(resultValue)
}

fun filter(constraint: CharSequence) {
    this.constraint = constraint
    filter.filter(constraint)
}

fun filter(constraint: CharSequence, listener: Filter.FilterListener) {
    this.constraint = constraint
    filter.filter(constraint, listener)
}

fun getFilter(): Filter {
    return filter
}

interface OnFilterObjectCallback {
    fun handle(countFilterObject: Int)
}

fun setOnFilterObjectCallback(objectCallback: OnFilterObjectCallback) {
    onFilterObjectCallback = objectCallback
}

inner class ArrayFilter : Filter() {
    private var original: ArrayList<T> = arrayListOf()
    private var filter: SimpleAdapterFilter<T> = DefaultFilter()
    private var list: ArrayList<T> = arrayListOf()
    private var values: ArrayList<T> = arrayListOf()


    fun setFilter(filter: SimpleAdapterFilter<T>): ArrayFilter {
        original = items
        this.filter = filter
        return this
    }

    override fun performFiltering(constraint: CharSequence?): Filter.FilterResults {
        val results = Filter.FilterResults()
        if (constraint == null || constraint.isBlank()) {
            synchronized(lock) {
                list = original
            }
            results.values = list
            results.count = list.size
        } else {
            synchronized(lock) {
                values = original
            }
            val result = ArrayList<T>()
            for (value in values) {
                if (constraint!=null && constraint.trim().isNotEmpty() && value != null) {
                    if (filter.onFilterItem(constraint, value)) {
                        result.add(value)
                    }
                } else {
                    value?.let { result.add(it) }
                }
            }
            results.values = result
            results.count = result.size
        }
        return results
    }

    override fun publishResults(constraint: CharSequence, results: Filter.FilterResults) {
        items = results.values as? ArrayList<T> ?: arrayListOf()
        notifyDataSetChanged()
        onFilterObjectCallback?.handle(results.count)
    }

}

class DefaultFilter<T> : SimpleAdapterFilter<T> {
    override fun onFilterItem(contains: CharSequence, item: T): Boolean {
        val valueText = item.toString().toLowerCase()
        if (valueText.startsWith(contains.toString())) {
            return true
        } else {
            val words = valueText.split(" ".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
            for (word in words) {
                if (word.contains(contains)) {
                    return true
                }
            }
        }
        return false
    }
  }
}

并利用实现方法对抽象适配器进行扩展

TasksAdapter.kt

import android.annotation.SuppressLint
  import kotlinx.android.synthetic.main.task_item_layout.view.*

class TasksAdapter(private val listener:TasksListener? = null) : SimpleAbstractAdapter<Task>() {
override fun getLayout(): Int {
    return R.layout.task_item_layout
}

override fun getDiffCallback(): DiffCallback<Task>? {
    return object : DiffCallback<Task>() {
        override fun areItemsTheSame(oldItem: Task, newItem: Task): Boolean {
            return oldItem.id == newItem.id
        }

        override fun areContentsTheSame(oldItem: Task, newItem: Task): Boolean {
            return oldItem.items == newItem.items
        }
    }
}

@SuppressLint("SetTextI18n")
override fun bindView(item: Task, viewHolder: VH) {
    viewHolder.itemView.apply {
        val position = viewHolder.adapterPosition
        val customer = item.customer
        val customerName = if (customer != null) customer.name else ""
        tvTaskCommentTitle.text = customerName + ", #" + item.id
        tvCommentContent.text = item.taskAddress
        ivCall.setOnClickListener {
            listener?.onCallClick(position, item)
        }
        setOnClickListener {
            listener?.onItemClick(position, item)
        }
    }
}

 interface TasksListener : SimpleAbstractAdapter.OnViewHolderListener<Task> {
    fun onCallClick(position: Int, item: Task)
 }
}

初始化适配器

mAdapter = TasksAdapter(object : TasksAdapter.TasksListener {
            override fun onCallClick(position: Int, item:Task) {
            }

            override fun onItemClick(position: Int, item:Task) {

            }
        })
rvTasks.adapter = mAdapter

并填写

mAdapter?.addAll(tasks)

添加自定义过滤器

mAdapter?.setFilter(object : SimpleAbstractAdapter.SimpleAdapterFilter<MoveTask> {
            override fun onFilterItem(contains: CharSequence, item:Task): Boolean {
                return contains.toString().toLowerCase().contains(item.id?.toLowerCase().toString())
            }
    })

过滤数据

mAdapter?.filter("test")

基于不同的资源,我使用简单库创建了RecyclerView的简单实现。

在build.gradle中添加这一行

implementation 'com.hereshem.lib:awesomelib:2.0.1'

通过在activity_main.xml中添加MyRecyclerView来创建一个RecyclerView

<com.hereshem.lib.recycler.MyRecyclerView
        android:id="@+id/recycler"
        app:layoutManager="LinearLayoutManager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

现在在MainActivity中,通过传递需要绑定的类的名称来创建一个ViewHolder

public static class EVHolder extends MyViewHolder<Events> {
    TextView date, title, summary;
    public EVHolder(View v) {
        super(v);
        date = v.findViewById(R.id.date);
        title = v.findViewById(R.id.title);
        summary = v.findViewById(R.id.summary);
    }
    @Override
    public void bindView(Events c) {
        date.setText(c.date);
        title.setText(c.title);
        summary.setText(c.summary);
    }
}

通过在适配器中传递项目、类和布局来创建Items列表变量和适配器,行数很少

List<Events> items = new ArrayList<>();
MyRecyclerView recycler = findViewById(R.id.recycler);
RecyclerViewAdapter adapter = new RecyclerViewAdapter(this, items, EVHolder.class, R.layout.row_event);
recycler.setAdapter(adapter);

ClickListener可以用以下几行添加

recycler.setOnItemClickListener(new MyRecyclerView.OnItemClickListener() {
    @Override
    public void onItemClick(int position) {
        Toast.makeText(MainActivity.this, "Recycler Item Clicked " + position, Toast.LENGTH_SHORT).show();
    }
});

都搞定了。

更多示例和实现可以在这里找到。 希望这能有所帮助!!

现在,您需要一个适配器来支持所有的RecyclerView

一个适配器可以用于所有的RecyclerView。NO onBindViewHolder, NO onCreateViewHolder处理。 没有从Java/Kotlin类设置适配器的代码。检查样本类。 您可以使用Binding Adapters为每个列表设置事件和自定义数据。

我在这里展示了通过1适配器设置两个不同的RecyclerView

activity_home.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

        <variable
            name="listOne"
            type="java.util.List"/>

        <variable
            name="listTwo"
            type="java.util.List"/>

        <variable
            name="onItemClickListenerOne"
            type="com.ks.nestedrecyclerbindingexample.callbacks.OnItemClickListener"/>

        <variable
            name="onItemClickListenerTwo"
            type="com.ks.nestedrecyclerbindingexample.callbacks.OnItemClickListener"/>

    </data>

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

        <android.support.v7.widget.RecyclerView
            rvItemLayout="@{@layout/row_one}"
            rvList="@{listOne}"
            rvOnItemClick="@{onItemClickListenerOne}"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layoutManager="android.support.v7.widget.LinearLayoutManager"
            />

        <android.support.v7.widget.RecyclerView
            rvItemLayout="@{@layout/row_two}"
            rvList="@{listTwo}"
            rvOnItemClick="@{onItemClickListenerTwo}"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layoutManager="android.support.v7.widget.LinearLayoutManager"
            />

    </LinearLayout>

</layout>

你可以看到我传递列表,项目布局id和点击listener从布局。

rvItemLayout="@{@layout/row_one}"
rvList="@{listOne}"
rvOnItemClick="@{onItemClickListenerOne}"

该自定义属性由BindingAdapter创建。

public class BindingAdapters {
    @BindingAdapter(value = {"rvItemLayout", "rvList", "rvOnItemClick"}, requireAll = false)
    public static void setRvAdapter(RecyclerView recyclerView, int rvItemLayout, List rvList, @Nullable OnItemClickListener onItemClickListener) {
        if (rvItemLayout != 0 && rvList != null && rvList.size() > 0)
            recyclerView.setAdapter(new GeneralAdapter(rvItemLayout, rvList, onItemClickListener));
    }
}

从Activity中,你传递list,点击listener like

HomeActivity.java

public class HomeActivity extends AppCompatActivity {
    ActivityHomeBinding binding;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_home);
        binding.setListOne(new ArrayList()); // pass your list or set list from response of API
        binding.setListTwo(new ArrayList());
        binding.setOnItemClickListenerOne(new OnItemClickListener() {
            @Override
            public void onItemClick(View view, Object object) {
                if (object instanceof ModelParent) {
                    // TODO: your action here
                }
            }
        });
        binding.setOnItemClickListenerTwo(new OnItemClickListener() {
            @Override
            public void onItemClick(View view, Object object) {
                if (object instanceof ModelChild) {
                    // TODO: your action here  
                }
            }
        });
    }
}

你不想读太多,直接克隆/下载完整的例子从我的github回购。你自己试试。

你可以在上面的repo中看到GeneralAdapter.java。

如果您在设置数据绑定时遇到问题,请参阅此回答。

我很高兴我不是唯一一个认为这些“最小”示例都涉及创建至少4个不同文件来创建一个简单工具的人。

下面是Kotlin中的一个独立活动(基于Saifur Rahman Mohsin的回答),它实现了一个基本的回收器视图:

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.constraintlayout.widget.ConstraintLayout
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView

class ModelDownloaderActivity : AppCompatActivity() {

    val items = (1..50).toList().map { "Item #$it" }
    inner class ItemHolder(view: View, var textField: TextView = view.findViewById(android.R.id.text1)) : RecyclerView.ViewHolder(view)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Create recycler view, or find it in Activity's XML file if you prefer
        val myLayoutResource: Int? = null // Replace with R.layout.activity_model_downloader if you want to use an XML layout with a recycler view in it
        val recyclerView = myLayoutResource?.let {
            setContentView(it)
            findViewById(R.id.modelRecyclerView) // Replace with ID of your recycler view in layout
        } ?: RecyclerView(this).also { setContentView(ConstraintLayout(this).apply { addView(it) }) }

        // Bind controls to it.
        recyclerView.layoutManager = LinearLayoutManager(this)
        recyclerView.adapter = object : RecyclerView.Adapter<ItemHolder>() {
            override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
                ItemHolder(LayoutInflater.from(parent.context).inflate(android.R.layout.simple_list_item_1, parent, false))
            override fun getItemCount() = items.size
            override fun onBindViewHolder(holder: ItemHolder, position: Int) {
                holder.textField.text = items[position]
                holder.textField.setOnClickListener {
                    Toast.makeText(this@ModelDownloaderActivity, "Clicked $position", Toast.LENGTH_SHORT).show()
                }
            }
        }
    }
}

实现androidx.recyclerview: recyclerview:… 建议更新到下面的androidx库:

https://developer.android.com/jetpack/androidx/releases/recyclerview

布局文件Widget XML标签必须更新为: androidx.recyclerview.widget.RecyclerView