如何解决Android RecyclerView 和自定义 Adapter 位置元素变化
我有一个填充了自定义适配器 recylerView.setAdapter(myAdapter) 的 RecylcerView，并且适配器通过 ArrayList 填充了不同的元素。在 ViewHolder 中，我覆盖了
public void onBindViewHolder(@NonNull ViewHolder viewHolder,int position) 方法。在自定义 ViewHolder 中，我放了一个按钮。该按钮上有一个单击侦听器。当我点击按钮时，我读取了变量 position 并且每次我点击同一个按钮时我都会面临变量的变化。
为什么会发生这种情况？
我的适配器是这样的：
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.amplifyframework.core.Amplify;
import com.amplifyframework.core.model.query.Where;
import com.amplifyframework.datastore.generated.model.Comments;
import com.amplifyframework.datastore.generated.model.Likes;
import com.amplifyframework.datastore.generated.model.Posts;
import com.bumptech.glide.Glide;
import com.bumptech.glide.load.engine.diskCacheStrategy;
import com.bumptech.glide.request.RequestOptions;
import com.google.firebase.auth.FirebaseAuth;
import java.net.URL;
import java.util.LinkedList;
import de.hdodenhof.circleimageview.CircleImageView;
import static com.amazonaws.mobile.auth.core.internal.util.ThreadUtils.runOnUiThread;
public class PostsAdapter extends RecyclerView.Adapter<PostsAdapter.PostViewHolder>
{
private LinkedList<Posts> usersPostsList;
private FirebaseAuth mAuth;
private Context context;
//private Boolean likeChecker;
private String currentUserId;
private MainActivity mainActivity;
private int currentPosition;
public PostsAdapter(Context context,String currentUserId,MainActivity mainActivity)
{
this.context = context;
this.currentUserId = currentUserId;
this.mainActivity = mainActivity;
}
public PostsAdapter(LinkedList<Posts> usersPostsList,Context context)
{
this.usersPostsList = usersPostsList;
this.context = context;
}
public void setMessages(LinkedList<Posts> usersPostsList) {
this.usersPostsList = usersPostsList;
}
public static class PostViewHolder extends RecyclerView.ViewHolder
{
View mView;
public static ImageButton LikePostButton,CommentPostButton;
public TextView displayNoOfLikes,modifyPost;
private TextView displayNoOfComments;
String currentUserID;
ExpandableTextView PostDescription;
private Context context;
public PostViewHolder(@NonNull View itemView,Context context)
{
super(itemView);
mView = itemView;
this.context = context;
LikePostButton = (ImageButton) mView.findViewById(R.id.like_button);
CommentPostButton = (ImageButton) mView.findViewById(R.id.comment_button);
displayNoOfLikes = (TextView) mView.findViewById(R.id.display_no_of_likes);
displayNoOfComments = (TextView) mView.findViewById(R.id.display_no_of_comments);
currentUserID = FirebaseAuth.getInstance().getCurrentUser().getUid();
modifyPost = mView.findViewById(R.id.modify_post);
}
public void setLikeButtonStatus(final String PostKey) {
Amplify.DataStore.query(
Likes.class,Where.matches(Likes.POST_ID.eq(PostKey.trim()).and(Likes.SENDER.eq(currentUserID.trim()))),items -> {
int countLikes = 0;
if (!items.hasNext()) {
LikePostButton.setimageResource(R.drawable.ic_star_border);
}
while (items.hasNext()) {
Likes item = items.next();
countLikes++;
LikePostButton.setimageResource(R.drawable.ic_star_fill);
Log.i("Amplify","Id " + item.getId());
}
int finalCountLikes = countLikes;
displayNoOfLikes.setText(finalCountLikes + (" Likes"));
},failure -> Log.e("Amplify","Could not query DataStore",failure)
);
}
public void setFullname(String fullname)
{
TextView username = (TextView) mView.findViewById(R.id.post_user_name);
username.setText(fullname);
}
public void setProfileimage(Context ctx,String profileimage)
{
CircleImageView image = (CircleImageView) mView.findViewById(R.id.post_profile_image);
Amplify.Storage.getUrl(profileimage,result -> {
URL url = result.getUrl();
runOnUiThread(() -> Glide.with(ctx)
.load(url)
.apply(new RequestOptions()
.diskCacheStrategy(diskCacheStrategy.NONE)
.skipMemoryCache(true))
.into(image));
},error -> Log.i("Amplify","error while retrieving url"));
}
public void setTime(String time)
{
TextView PostTime = (TextView) mView.findViewById(R.id.post_time);
PostTime.setText(" " + time);
}
public void setDate(String date)
{
TextView PostDate = (TextView) mView.findViewById(R.id.post_date);
PostDate.setText(" " + date);
}
public void setDescription(String description)
{
PostDescription = mView.findViewById(R.id.post_description);
PostDescription.setText(description);
}
public void setPostimage(Context ctx,String postimage,String id)
{
ImageView postimageInner = mView.findViewById(R.id.post_image);
Amplify.Storage.getUrl(postimage,result -> {
URL url = result.getUrl();
runOnUiThread(() -> Glide.with(ctx)
.load(url)
.apply(new RequestOptions()
.diskCacheStrategy(diskCacheStrategy.NONE)
.skipMemoryCache(true))
.into(postimageInner));
Log.i("Amplify---------","url ok----");
},error -> Log.e("Amplify---------","error while retrieving url: " + error.getCause().toString()));
postimageInner.setonClickListener(v -> {
Intent clickPostIntent = new Intent(context,ClickPostActivity.class);
clickPostIntent.putExtra("PostKey",id);
clickPostIntent.putExtra("postimagePath",postimage);
context.startActivity (clickPostIntent);
});
}
public void setCountry(String country)
{
TextView CountryName = (TextView) mView.findViewById(R.id.post_country_name);
CountryName.setText(country);
}
public void setCity(String city)
{
TextView City = (TextView) mView.findViewById(R.id.post_city_name);
City.setText("- " + city);
}
public void setCommentStatus(final String PostKey) {
Amplify.DataStore.query(
Comments.class,Where.matches(Comments.POST_ID.eq(PostKey.trim())),items -> {
int i = 0;
while (items.hasNext()) {
Comments comments = items.next();
i++;
int finalI = i;
runOnUiThread(() -> displayNoOfComments.setText(finalI + " comments"));
Log.i("amplify?","comment id: " + comments.getId());
}
},failure)
);
}
}
@NonNull
@Override
public PostViewHolder onCreateViewHolder(@NonNull ViewGroup parent,int viewType)
{
View V = LayoutInflater.from(parent.getContext())
.inflate(R.layout.all_posts_layout,parent,false);
mAuth = FirebaseAuth.getInstance();
return new PostViewHolder(V,context);
}
@Override
public int getItemViewType(int position) {
currentPosition = position;
return position;
}
@Override
public void onBindViewHolder(@NonNull PostViewHolder viewHolder,int position) {
viewHolder.setFullname(usersPostsList.get(position).getFullname());
viewHolder.setTime(usersPostsList.get(position).getTime());
viewHolder.setDate(usersPostsList.get(position).getDate());
viewHolder.setDescription(usersPostsList.get(position).getDescription());
viewHolder.setProfileimage(context,usersPostsList.get(position).getProfileimage());
viewHolder.setPostimage(context,usersPostsList.get(position).getPostimage(),usersPostsList.get(position).getId());
viewHolder.setCountry(usersPostsList.get(position).getCountry());
viewHolder.setCity(usersPostsList.get(position).getCity());
if( viewHolder.PostDescription.originalText.length() > 100 ) {
viewHolder.PostDescription.setonClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!((ExpandableTextView)v).read) {
((ExpandableTextView)v).expandText();
((ExpandableTextView)v).read = true;
} else {
((ExpandableTextView)v).truncateText();
((ExpandableTextView)v).read = false;
}
}
});
}
viewHolder.CommentPostButton.setonClickListener(v -> {
Intent commentsIntent = new Intent(context,CommentActivity.class);
commentsIntent.putExtra("PostKey",usersPostsList.get(currentPosition).getId());
context.startActivity(commentsIntent);
});
viewHolder.LikePostButton.setonClickListener(v -> {
Amplify.DataStore.query(
Likes.class,Where.matches(Likes.POST_ID.eq(usersPostsList.get(currentPosition).getId().trim())
.and(Likes.SENDER.eq(currentUserId.trim()))
.and((Likes.RECEIVER.eq(usersPostsList.get(currentPosition).getUid())))
),items -> {
if (items.hasNext()) {
Likes item = items.next();
Amplify.DataStore.delete(item,deleted -> Log.i("Amplify","Deleted item."),"Delete Failed.",failure)
);
Log.i("Amplify","Id " + item.getId());
} else {
Likes likes = Likes.builder()
.receiver(usersPostsList.get(currentPosition).getUid().trim())
.sender(currentUserId.trim())
.postId(usersPostsList.get(currentPosition).getId().trim())
.value("true")
.build();
Amplify.DataStore.save(
likes,success -> Log.i("Amplify","Item updated: " + success.item().getId()),error -> Log.e("Amplify","Could not save item to DataStore",error)
);
}
},failure -> {
Log.e("Amplify",failure);
}
);
notifyDataSetChanged();
});
viewHolder.modifyPost.setonClickListener(v -> {
Intent intent = new Intent(context,ClickPostActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
intent.putExtra("PostKey",usersPostsList.get(currentPosition).getId());
intent.putExtra("postimagePath",usersPostsList.get(currentPosition).getPostimage());
context.startActivity(intent);
});
}
@Override
public int getItemCount() {
return usersPostsList.size() ;
}
}
似乎在单击 LikePostButton 后调用了 getItemViewType 方法，以便：viewHolder.LikePostButton.setonClickListener(v -> { 获取旧的 currentPosition 变量值
感谢所有帮助我理解的人
解决方法
您可以覆盖 getItemViewType(position:Int) 方法并替换 super 行以在 Kotlin 中仅使用这样的位置返回它：
override fun getItemViewType(position: Int): Int {
return position
}
在 Java 中：
@Override
public int getItemViewType(int position) {
return position;
}
谢谢，我解决了它在 ViewHolder 中的按钮上设置侦听器，然后只需调用 getAbsoluteAdapterPosition() 以获得正确位置
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