RecyclerView - 在特定位置获取视图 [英] RecyclerView - Get view at particular position
问题描述
我的活动包含 RecyclerView 和 ImageView 。我正在使用 RecyclerView 水平显示图像列表。当我点击 RecyclerView 中的图像时，活动中的 ImageView 应该会显示更大的图像。到目前为止一切正常。
I have an activity with a RecyclerView and an ImageView. I am using the RecyclerView to show a list of images horizontally. When I click on an image in the RecyclerView the ImageView in the activity should show a bigger picture of the image. So far everything works fine.
现在活动中还有两个 ImageButtons ： imageButton_left 和 imageButton_right 。当我点击 imageButton_left 时， ImageView 中的图像应向左转，并且<$ c中的缩略图$ c> RecyclerView 应反映此更改。类似于 imageButton_right 的情况。
Now there are two more ImageButtons in the activity: imageButton_left and imageButton_right. When I click on imageButton_left, the image in the ImageView should turn left and also, the thumbnail in the RecyclerView should reflect this change. Similar is the case with imageButton_right.
我能够旋转 ImageView 。但是，如何在 RecyclerView 中旋转缩略图？如何获得 ViewHolder 的 ImageView ？
I am able to rotate the ImageView. But, how can I rotate the thumbnail in the RecyclerView? How can I get the ViewHolder's ImageView?
代码：
活动XML：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="match_parent"
android:orientation="vertical">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:orientation="vertical">
<ImageView
android:id="@+id/original_image"
android:layout_width="200dp"
android:layout_height="200dp"
android:scaleType="fitXY"
android:src="@drawable/image_not_available_2" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:gravity="center_horizontal"
android:orientation="horizontal">
<ImageButton
android:id="@+id/imageButton_left"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="20dp"
android:background="@drawable/rotate_left_icon" />
<ImageButton
android:id="@+id/imageButton_right"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/rotate_right_icon" />
</LinearLayout>
</LinearLayout>
</LinearLayout>
我的活动代码：
public class SecondActivity extends AppCompatActivity implements IRecyclerViewClickListener {
RecyclerView mRecyclerView;
LinearLayoutManager mLayoutManager;
RecyclerViewAdapter mRecyclerViewAdapter;
List<String> urls = new ArrayList<String>();
ImageView mOriginalImageView;
ImageButton mLeftRotate, mRightRotate;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
urls.clear();
mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);
mLayoutManager = new LinearLayoutManager(this, android.support.v7.widget.LinearLayoutManager.HORIZONTAL, false);
mLayoutManager.setOrientation(android.support.v7.widget.LinearLayoutManager.HORIZONTAL);
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerViewAdapter = new RecyclerViewAdapter(this, urls);
mRecyclerView.setAdapter(mRecyclerViewAdapter);
mOriginalImageView = (ImageView) findViewById(R.id.original_image);
mLeftRotate = (ImageButton) findViewById(R.id.imageButton_left);
mLeftRotate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mOriginalImageView.setRotation(mOriginalImageView.getRotation() - 90);
}
});
mRightRotate = (ImageButton) findViewById(R.id.imageButton_right);
mRightRotate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mOriginalImageView.setRotation(mOriginalImageView.getRotation() + 90);
}
});
Intent intent = getIntent();
if (intent != null) {
String portfolio = intent.getStringExtra("portfolio");
try {
JSONArray jsonArray = new JSONArray(portfolio);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
String url = jsonObject.getString("url");
urls.add(url);
}
Log.d(Const.DEBUG, "URLs: " + urls.toString());
mRecyclerViewAdapter.notifyDataSetChanged();
} catch (Exception e) {
e.printStackTrace();
}
}
}
@Override
public void onItemClick(int position) {
Picasso.with(this).load(urls.get(position)).into(mOriginalImageView);
}
}
我的RecyclerView自定义适配器：
My Custom Adapter for RecyclerView:
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
Context context;
List<String> mUrls = new ArrayList<String>();
IRecyclerViewClickListener mIRecyclerViewClickListener;
public int position;
public int getPosition() {
return position;
}
public void setPosition(int position) {
this.position = position;
}
public RecyclerViewAdapter(Context context, List<String> urls) {
this.context = context;
this.mUrls.clear();
this.mUrls = urls;
Log.d(Const.DEBUG, "Urls Size: " + urls.size());
Log.d(Const.DEBUG, urls.toString());
if (context instanceof IRecyclerViewClickListener)
mIRecyclerViewClickListener = (IRecyclerViewClickListener) context;
else
Log.d(Const.DEBUG, "Implement IRecyclerViewClickListener in Activity");
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(context).inflate(R.layout.item_horizontal_recyclerview, parent, false);
ViewHolder holder = new ViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Picasso.with(context).load(mUrls.get(position)).into(holder.mImageView);
}
@Override
public int getItemCount() {
return mUrls.size();
}
public void rotateThumbnail() {
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public ImageView mImageView;
public View v;
public ViewHolder(View v) {
super(v);
v.setTag(getAdapterPosition());
v.setOnClickListener(this);
this.mImageView = (ImageView) v.findViewById(R.id.image);
}
@Override
public void onClick(View v) {
this.v = v;
mIRecyclerViewClickListener.onItemClick(getAdapterPosition());
}
}
}
推荐答案
我想您使用的是 LinearLayoutManager 显示列表。它有一个很好的方法叫做 findViewByPosition
I suppose you are using a LinearLayoutManager to show the list. It has a nice method called findViewByPosition that
查找代表给定适配器位置的视图。
Finds the view which represents the given adapter position.
您所需要的只是您感兴趣的项目的适配器位置。
All you need is the adapter position of the item you are interested in.
编辑：正如 Paul Woitaschek 在评论中所述， findViewByPosition 是一种<$ c $的方法c> LayoutManager 所以它适用于所有LayoutManagers（即 StaggeredGridLayoutManager 等）
edit: as noted by Paul Woitaschek in the comments, findViewByPosition is a method of LayoutManager so it would work with all LayoutManagers (i.e. StaggeredGridLayoutManager, etc.)
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