我知道RecyclerView
已经取代了以前ListView
和GridView
的功能。我正在寻找一个非常基本的例子,展示使用RecyclerView
的最小网格设置。我不是在寻找长篇大论式的解释,只是一个最小的例子。我想模仿旧的GridView的最简单的网格应该包括以下功能。
对于那些已经熟悉设置`RecyclerView'来制作列表的人来说,好消息是制作网格的方法大致相同。你只是在设置RecyclerView'的时候使用
GridLayoutManager'而不是`LinearLayoutManager'。
recyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));
如果你需要更多的帮助,那么请看下面的例子。
下面是一个最小的例子,看起来会像下面的图片。
从一个空的活动开始。你将执行以下任务来添加RecyclerView
网格。你所需要做的就是复制和粘贴每个部分的代码。以后你可以根据自己的需要进行定制。
确保在你的应用程序gradle.build
文件中包含以下依赖项。
compile 'com.android.support:appcompat-v7:27.1.1'
compile 'com.android.support:recyclerview-v7:27.1.1'
你可以将版本号更新为任何最新的。
在你的xml布局中加入RecyclerView
。
activity_main.xml。
<?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/rvNumbers"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</RelativeLayout>
在我们的RecyclerView'网格中,每个单元格都将只有一个
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:orientation="horizontal"
android:padding="5dp"
android:layout_width="50dp"
android:layout_height="50dp">
<TextView
android:id="@+id/info_text"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:background="@color/colorAccent"/>
</LinearLayout>
RecyclerView "需要一个适配器来将你的数据填充到每个单元格的视图中。创建一个新的java文件。
MyRecyclerViewAdapter.java。
public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ViewHolder> {
private String[] mData;
private LayoutInflater mInflater;
private ItemClickListener mClickListener;
// data is passed into the constructor
MyRecyclerViewAdapter(Context context, String[] data) {
this.mInflater = LayoutInflater.from(context);
this.mData = data;
}
// inflates the cell 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 TextView in each cell
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
holder.myTextView.setText(mData[position]);
}
// total number of cells
@Override
public int getItemCount() {
return mData.length;
}
// stores and recycles views as they are scrolled off screen
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView myTextView;
ViewHolder(View itemView) {
super(itemView);
myTextView = itemView.findViewById(R.id.info_text);
itemView.setOnClickListener(this);
}
@Override
public void onClick(View view) {
if (mClickListener != null) mClickListener.onItemClick(view, getAdapterPosition());
}
}
// convenience method for getting data at click position
String getItem(int id) {
return mData[id];
}
// allows clicks events to be caught
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);
}
}
注意事项
GridView
中是可用的,而且是一个常见的需求。如果你不需要,你可以删除这段代码。在你的主活动中添加以下代码。
MainActivity.java
public class MainActivity extends AppCompatActivity implements MyRecyclerViewAdapter.ItemClickListener {
MyRecyclerViewAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// data to populate the RecyclerView with
String[] data = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48"};
// set up the RecyclerView
RecyclerView recyclerView = findViewById(R.id.rvNumbers);
int numberOfColumns = 6;
recyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));
adapter = new MyRecyclerViewAdapter(this, data);
adapter.setClickListener(this);
recyclerView.setAdapter(adapter);
}
@Override
public void onItemClick(View view, int position) {
Log.i("TAG", "You clicked number " + adapter.getItem(position) + ", which is at cell position " + position);
}
}
注意事项
就这样了。你现在应该可以运行你的项目并得到类似于顶部图片的东西。
圆角
自动拟合列
虽然我很喜欢和欣赏Suragch'的回答,但我想留个言,因为我发现为Adapter(MyRecyclerViewAdapter
)编码来定义和暴露Listener方法onItemClick
并不是最好的方法,因为没有正确使用类封装。所以我的建议是让Adapter只处理监听操作(这是他的目的!),并将其与使用Adapter的活动(MainActivity
)分开。因此,我将这样设置适配器类。
MyRecyclerViewAdapter.java。
public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ViewHolder> {
private String[] mData = new String[0];
private LayoutInflater mInflater;
// Data is passed into the constructor
public MyRecyclerViewAdapter(Context context, String[] data) {
this.mInflater = LayoutInflater.from(context);
this.mData = data;
}
// Inflates the cell layout from xml when needed
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.recyclerview_item, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
// Binds the data to the textview in each cell
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
String animal = mData[position];
holder.myTextView.setText(animal);
}
// Total number of cells
@Override
public int getItemCount() {
return mData.length;
}
// Stores and recycles views as they are scrolled off screen
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView myTextView;
public ViewHolder(View itemView) {
super(itemView);
myTextView = (TextView) itemView.findViewById(R.id.info_text);
itemView.setOnClickListener(this);
}
@Override
public void onClick(View view) {
onItemClick(view, getAdapterPosition());
}
}
// Convenience method for getting data at click position
public String getItem(int id) {
return mData[id];
}
// Method that executes your code for the action received
public void onItemClick(View view, int position) {
Log.i("TAG", "You clicked number " + getItem(position).toString() + ", which is at cell position " + position);
}
}
请注意onItemClick
方法现在定义在MyRecyclerViewAdapter
中,这是你想为收到的事件/动作编写任务的地方。
为了完成这一转变,只需要做一个小小的改变:Activity不需要再实现MyRecyclerViewAdapter.ItemClickListener
,因为现在这完全由Adapter完成。这将是最后的修改。
MainActivity.java
public class MainActivity extends AppCompatActivity {
MyRecyclerViewAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// data to populate the RecyclerView with
String[] data = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48"};
// set up the RecyclerView
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.rvNumbers);
int numberOfColumns = 6;
recyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));
adapter = new MyRecyclerViewAdapter(this, data);
adapter.setClickListener(this);
recyclerView.setAdapter(adapter);
}
}