为什么不工作notifyItemChanged(Why does not work notifyItemChanged)
我知道这可能是一个愚蠢的问题，但我找不到答案。 我问你的帮助。
我有一个使用LinearLayoutManager的RecyclerView和一个自定义的RecyclerView.Adapter。
我的数据类：
public class Img extends ArrayList<Img> { int id = 0; String filepath = ""; boolean checked = false; int progress = 0; ... getters and setters... }活动代码：
File folder = new File("My path"); File[] files = folder.listFiles(); int id = 0; for (File file : files) { if (!file.isDirectory()) { Img img = new Img(); img.setId(id); img.setFilepath(file.toString()); imgs.add(img); ++id; } } mAdapter = new GalleryAdapter(getApplicationContext(), imgs); RecyclerView.LayoutManager mLayoutManager = new GridLayoutManager(getApplicationContext(), 2); recyclerView.setLayoutManager(mLayoutManager); recyclerView.setItemAnimator(new DefaultItemAnimator()); recyclerView.setAdapter(mAdapter);和适配器：
@Override public void onBindViewHolder(final MyViewHolder holder, final int position) { Img item = imgs.get(position); holder.txt.setText(String.valueOf(item.getProgress())); holder.thumbnail.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { File source = new File(imgs.get(position).getFilepath()); String strFileName = source.getName(); File destination = new File("My path" + "/" + strFileName); try { InputStream input = null; OutputStream output = null; long lenghtOfFile = source.length(); int count; try { input = new FileInputStream(source); output = new FileOutputStream(destination); byte[] data = new byte[1024]; long total = 0; int xc2 = 0; while ((count = input.read(data)) != -1) { total += count; int xc = (int) ((total * 100) / lenghtOfFile); output.write(data, 0, count); imgs.get(position).setProgress(xc); notifyItemChanged(position); try { Thread.sleep(20); } catch (InterruptedException e) { e.printStackTrace(); } } } finally { output.flush(); output.close(); input.close(); } } catch (IOException e) { e.printStackTrace(); } } });为什么notifyItemChanged（position）只在操作完成后才被触发并提交给TextView（txt）只有100的值？
UPD：此代码不起作用
@Override public MyViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) { final View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.gallery_thumbnail, parent, false); final MyViewHolder holder = new MyViewHolder(itemView); itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { final int position = holder.getAdapterPosition(); if (position != RecyclerView.NO_POSITION) { File source = new File(imgs.get(position).getFilepath()); String strFileName = source.getName(); File destination = new File("My path" + "/" + strFileName); try { InputStream input = null; OutputStream output = null; long lenghtOfFile = source.length(); int count; try { input = new FileInputStream(source); output = new FileOutputStream(destination); byte[] data = new byte[1024]; long total = 0; int xc2 = 0; while ((count = input.read(data)) != -1) { total += count; int xc = (int) ((total * 100) / lenghtOfFile); output.write(data, 0, count); if (xc2!=xc){ //holder.progress_bar.setProgress(xc); imgs.get(position).setProgress(xc); notifyItemChanged(position); try { Thread.sleep(40); } catch (InterruptedException e) { e.printStackTrace(); } } xc2 = xc; } } finally { output.flush(); output.close(); input.close(); } } catch (IOException e) { e.printStackTrace(); } } } }); return holder; }UPD2：此代码不起作用
@Override public MyViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) { View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.gallery_thumbnail, parent, false); final MyViewHolder holder = new MyViewHolder(itemView); itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { final int position = holder.getAdapterPosition(); if (position != RecyclerView.NO_POSITION) { for (int i=1; i<=100; ++i) { imgs.get(position).setProgress(i); notifyItemChanged(position); try { Thread.sleep(50); } catch (InterruptedException e) { e.printStackTrace(); } } } } }); //return new MyViewHolder(itemView); return holder; }I understand that it is possible a silly question but I can not find the answer to it. I ask your help.
I have a RecyclerView using a LinearLayoutManager, and a custom RecyclerView.Adapter.
My data class:
public class Img extends ArrayList<Img> { int id = 0; String filepath = ""; boolean checked = false; int progress = 0; ... getters and setters... }Code in activity:
File folder = new File("My path"); File[] files = folder.listFiles(); int id = 0; for (File file : files) { if (!file.isDirectory()) { Img img = new Img(); img.setId(id); img.setFilepath(file.toString()); imgs.add(img); ++id; } } mAdapter = new GalleryAdapter(getApplicationContext(), imgs); RecyclerView.LayoutManager mLayoutManager = new GridLayoutManager(getApplicationContext(), 2); recyclerView.setLayoutManager(mLayoutManager); recyclerView.setItemAnimator(new DefaultItemAnimator()); recyclerView.setAdapter(mAdapter);and adapter:
@Override public void onBindViewHolder(final MyViewHolder holder, final int position) { Img item = imgs.get(position); holder.txt.setText(String.valueOf(item.getProgress())); holder.thumbnail.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { File source = new File(imgs.get(position).getFilepath()); String strFileName = source.getName(); File destination = new File("My path" + "/" + strFileName); try { InputStream input = null; OutputStream output = null; long lenghtOfFile = source.length(); int count; try { input = new FileInputStream(source); output = new FileOutputStream(destination); byte[] data = new byte[1024]; long total = 0; int xc2 = 0; while ((count = input.read(data)) != -1) { total += count; int xc = (int) ((total * 100) / lenghtOfFile); output.write(data, 0, count); imgs.get(position).setProgress(xc); notifyItemChanged(position); try { Thread.sleep(20); } catch (InterruptedException e) { e.printStackTrace(); } } } finally { output.flush(); output.close(); input.close(); } } catch (IOException e) { e.printStackTrace(); } } });Why notifyItemChanged (position) is triggered only after the operation is completed and submitted to the TextView (txt) only the value of 100?
UPD: This code does not work
@Override public MyViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) { final View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.gallery_thumbnail, parent, false); final MyViewHolder holder = new MyViewHolder(itemView); itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { final int position = holder.getAdapterPosition(); if (position != RecyclerView.NO_POSITION) { File source = new File(imgs.get(position).getFilepath()); String strFileName = source.getName(); File destination = new File("My path" + "/" + strFileName); try { InputStream input = null; OutputStream output = null; long lenghtOfFile = source.length(); int count; try { input = new FileInputStream(source); output = new FileOutputStream(destination); byte[] data = new byte[1024]; long total = 0; int xc2 = 0; while ((count = input.read(data)) != -1) { total += count; int xc = (int) ((total * 100) / lenghtOfFile); output.write(data, 0, count); if (xc2!=xc){ //holder.progress_bar.setProgress(xc); imgs.get(position).setProgress(xc); notifyItemChanged(position); try { Thread.sleep(40); } catch (InterruptedException e) { e.printStackTrace(); } } xc2 = xc; } } finally { output.flush(); output.close(); input.close(); } } catch (IOException e) { e.printStackTrace(); } } } }); return holder; }UPD2: This code does not work
@Override public MyViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) { View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.gallery_thumbnail, parent, false); final MyViewHolder holder = new MyViewHolder(itemView); itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { final int position = holder.getAdapterPosition(); if (position != RecyclerView.NO_POSITION) { for (int i=1; i<=100; ++i) { imgs.get(position).setProgress(i); notifyItemChanged(position); try { Thread.sleep(50); } catch (InterruptedException e) { e.printStackTrace(); } } } } }); //return new MyViewHolder(itemView); return holder; }最满意答案
基本上你在UI线程上加载你的文件，所以你每次调用notifyItemChanged（）都会向Looper添加一个任务，但只有当你完成加载时，Looper才能完成任务，你只能看到100。
我会在不同的线程上运行负载，如下所示：
new View.OnClickListener() { @Override public void onClick(View view) { File source = new File(imgs.get(position).getFilepath()); String strFileName = source.getName(); File destination = new File("My path" + "/" + strFileName); **> Thread t1 = new Thread(new Runnable(){ public void run(){ <** try { InputStream input = null; OutputStream output = null; long lenghtOfFile = source.length(); int count; try { input = new FileInputStream(source); output = new FileOutputStream(destination); byte[] data = new byte[1024]; long total = 0; int xc2 = 0; while ((count = input.read(data)) != -1) { total += count; int xc = (int) ((total * 100) / lenghtOfFile); output.write(data, 0, count); imgs.get(position).setProgress(xc); notifyItemChanged(position); try { Thread.sleep(20); } catch (InterruptedException e) { e.printStackTrace(); } } } finally { output.flush(); output.close(); input.close(); } } catch (IOException e) { e.printStackTrace(); } } t1.start(); } }多数民众赞成我的猜测，祝你好运！
Basically your'e doing your'e file loading on the UI thread, so everytime you call to notifyItemChanged() you add a task to the Looper but the Looper gets to that task only when you finish the loading therefor you only see the 100.
I would run the load on a different thread like so:
new View.OnClickListener() { @Override public void onClick(View view) { File source = new File(imgs.get(position).getFilepath()); String strFileName = source.getName(); File destination = new File("My path" + "/" + strFileName); **> Thread t1 = new Thread(new Runnable(){ public void run(){ <** try { InputStream input = null; OutputStream output = null; long lenghtOfFile = source.length(); int count; try { input = new FileInputStream(source); output = new FileOutputStream(destination); byte[] data = new byte[1024]; long total = 0; int xc2 = 0; while ((count = input.read(data)) != -1) { total += count; int xc = (int) ((total * 100) / lenghtOfFile); output.write(data, 0, count); imgs.get(position).setProgress(xc); notifyItemChanged(position); try { Thread.sleep(20); } catch (InterruptedException e) { e.printStackTrace(); } } } finally { output.flush(); output.close(); input.close(); } } catch (IOException e) { e.printStackTrace(); } } t1.start(); } }Thats my guess, good luck!
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