保存在RecyclerView的EditText内容 [英] Saving EditText content in RecyclerView

问题描述

我有一个的EditText 列表项的话，我不知道有多少项目会出现。 我有一个问题，当我进入的EditText 一些文本，然后向下滚动 RecyclerView ，之后我一直滚动再次出现在没有文字我的第一个的EditText 。

I have list item with EditText in it, I don't know how many items there will be. I have a problem when I enter some text in EditText, and then scroll down a RecyclerView, after I've scroll up again there is no text in my first EditText.

我想知道什么，在哪里我应该写code，这样当用户键入或完成输入（我在想这样做有一个 TextWatcher ）在的EditText 文本被保存到到一个文件中（我将它保存在一个.txt文件中的外部存储）

I am wondering what, and where should I write code so that while the user is typing or finished typing (I was thinking to do that with a TextWatcher) in the EditText the text gets saved into into a file (I'll save it in a .txt file in the external storage)

我应该这样做活动的的onCreate 法或适配器类或其他地方？

Am I supposed to do so in the onCreate method of the activity or in the adapter class or elsewhere?

下面是一些code

 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);
    }

我的适配器code

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code工作正常滚动的时候obviusly不保存编辑文本的内容。如果我添加此code，当我滚动的熄灭屏幕，比回来搞砸内容的所有EDITTEXT意见。

without this "addtextChangedListener" my code works fine obviusly not saving the content of the edit Text when scrolled. If i add this code, when i scroll all editText views that go off screen and than come back in have messed up content.

推荐答案

与您的解决方案分配和分配TextWatcher在onBindViewHolder这是一个昂贵的操作，将在快速滚动引进滞后，这也似乎干扰确定的主要问题什么位置更新mAdapter。

The major problem with your solution is allocating and assigning TextWatcher in onBindViewHolder which is an expensive operation that will introduce lags during fast scrolls and it also seems to interfere with determining what position to update in mAdapter.

使所有业务onCreateViewHolder是一个比较preferable选项。下面是完整的测试工作液：

Making all operations in onCreateViewHolder is a more preferable option. Here is the complete tested working solution:

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(position);
        holder.mEditText.setText(mDataset[position]);
    }

    @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
        }
    }
}

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