我有一个带有EditText的列表项，我不知道会有多少项。当我在EditText中输入一些文本，然后向下滚动回收站视图时，我遇到了一个问题，当我再次向上滚动后，我的第一个
我想知道我应该写什么，在哪里写代码，这样当用户在EditText中键入或完成键入（我想用一个TextWatcher>来完成）时，文本会保存到一个文件中（我将它保存在外部存储的.txt文件中）
我应该在活动的onCreate方法中，还是在适配器类或其他地方这样做？
下面是一些代码
public class MainActivity extends Activity {
RecyclerView mRecyclerView;
MyAdapter mAdapter;
String[] mDataSet= new String[20];
@Override
protected void onCreate(Bundle savedInstanceState) {
// generating text for editText Views
for (int i = 0; i<=19; i++){
mDataSet[i]= "EditText n: "+i;
}
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mAdapter = new MyAdapter(mDataSet);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setHasFixedSize(true);
}
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private String[] mDataset;
public static class ViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public EditText mEditText;
public ViewHolder(View v) {
super(v);
mEditText = (EditText) v.findViewById(R.id.list_item_edittext);
}
}
public MyAdapter(String[] myDataset) {
mDataset = myDataset;
}
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.list_item, parent, false);
ViewHolder vh = new ViewHolder(v);
return vh;
}
@Override
public void onBindViewHolder(ViewHolder holder, final int position) {
holder.mEditText.setText(mDataset[position]);
//without this addtextChangedListener my code works fine ovbiusly
// not saving the content of the edit Text when scrolled
// If i add this code then when i scroll all textView that go of screen
// and than come back in have messed up content
holder.mEditText.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start,
int before, int count) {
//setting data to array, when changed
// this is a semplified example in the actual app i save the text
// in a .txt in the external storage
mDataset[position] = s.toString();
}
@Override
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
@Override
public void afterTextChanged(Editable s) {
}
});
}
@Override
public int getItemCount() {
return mDataset.length;
}
如果没有这个“addtextChangedListener ”,我的代码工作得很好，显然不会在滚动时保存编辑文本的内容。如果我添加了这段代码，当我滚动所有的editText视图时，这些视图都离开了屏幕，然后又回来，这些视图弄乱了内容。
您的解决方案的主要问题是在onBindViewHolder中分配和分配TextWatcher，这是一项昂贵的操作，在快速滚动期间会产生延迟，并且似乎还会干扰确定mAdapter中要更新的位置。
在onCreateViewHolder中进行所有操作是更可取的选择。以下是经过测试的完整工作解决方案：
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private String[] mDataset;
public MyAdapter(String[] myDataset) {
mDataset = myDataset;
}
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_edittext, parent, false);
// pass MyCustomEditTextListener to viewholder in onCreateViewHolder
// so that we don't have to do this expensive allocation in onBindViewHolder
ViewHolder vh = new ViewHolder(v, new MyCustomEditTextListener());
return vh;
}
@Override
public void onBindViewHolder(ViewHolder holder, final int position) {
// update MyCustomEditTextListener every time we bind a new item
// so that it knows what item in mDataset to update
holder.myCustomEditTextListener.updatePosition(holder.getAdapterPosition());
holder.mEditText.setText(mDataset[holder.getAdapterPosition()]);
}
@Override
public int getItemCount() {
return mDataset.length;
}
public static class ViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public EditText mEditText;
public MyCustomEditTextListener myCustomEditTextListener;
public ViewHolder(View v, MyCustomEditTextListener myCustomEditTextListener) {
super(v);
this.mEditText = (EditText) v.findViewById(R.id.editText);
this.myCustomEditTextListener = myCustomEditTextListener;
this.mEditText.addTextChangedListener(myCustomEditTextListener);
}
}
// we make TextWatcher to be aware of the position it currently works with
// this way, once a new item is attached in onBindViewHolder, it will
// update current position MyCustomEditTextListener, reference to which is kept by ViewHolder
private class MyCustomEditTextListener implements TextWatcher {
private int position;
public void updatePosition(int position) {
this.position = position;
}
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3) {
// no op
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {
mDataset[position] = charSequence.toString();
}
@Override
public void afterTextChanged(Editable editable) {
// no op
}
}
}
我也有同样的问题，我添加了下面一行，它似乎已经修复了我这边的问题。
mRecyclerview.setItemViewCacheSize(mDataset.size());
希望这能解决你这边的问题。
我实现了@dkarmazi解决方案，但它对我没有帮助。所以，我走得更远了，有一个真正有效的解决方案。
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private String[] mDataset;
public MyAdapter(String[] myDataset) {
mDataset = myDataset;
}
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_edittext, parent, false);
// pass MyCustomEditTextListener to viewholder in onCreateViewHolder
// so that we don't have to do this expensive allocation in onBindViewHolder
ViewHolder vh = new ViewHolder(v, new MyCustomEditTextListener());
return vh;
}
@Override
public void onBindViewHolder(ViewHolder holder, final int position) {
// update MyCustomEditTextListener every time we bind a new item
// so that it knows what item in mDataset to update
holder.myCustomEditTextListener.updatePosition(holder.getAdapterPosition());
holder.mEditText.setText(mDataset[holder.getAdapterPosition()]);
}
@Override
public int getItemCount() {
return mDataset.length;
}
@Override
public void onViewAttachedToWindow(@NonNull RecyclerView.ViewHolder holder) {
((ViewHolder) holder).enableTextWatcher();
}
@Override
public void onViewDetachedFromWindow(@NonNull RecyclerView.ViewHolder holder) {
((ViewHolder) holder).disableTextWatcher();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public EditText mEditText;
public MyCustomEditTextListener myCustomEditTextListener;
public ViewHolder(View v, MyCustomEditTextListener myCustomEditTextListener) {
super(v);
this.mEditText = (EditText) v.findViewById(R.id.editText);
this.myCustomEditTextListener = myCustomEditTextListener;
}
void enableTextWatcher() {
mEditText.addTextChangedListener(myCustomEditTextListener);
}
void disableTextWatcher() {
mEditText.removeTextChangedListener(myCustomEditTextListener);
}
}
// we make TextWatcher to be aware of the position it currently works with
// this way, once a new item is attached in onBindViewHolder, it will
// update current position MyCustomEditTextListener, reference to which is kept by ViewHolder
private class MyCustomEditTextListener implements TextWatcher {
private int position;
public void updatePosition(int position) {
this.position = position;
}
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3) {
// no op
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {
mDataset[position] = charSequence.toString();
}
@Override
public void afterTextChanged(Editable editable) {
// no op
}
}
}
主要问题是应用的TextWatcher在物品回收过程中继续工作。
我试过在回收之前禁用它，但是没有任何“beforeRecycle”事件方法。所以我使用了onViewDetachedFromWindow方法，效果很好。
