在RecyclerView中保存EditText内容

Question

我有列表项目EditText,我不知道会有多少项目.当我输入一些文本时EditText,我有一个问题,然后向下滚动RecyclerView,在我再次向上滚动后,我的第一个没有文字EditText.

我想知道什么,我应该在哪里编写代码,以便在用户输入或完成输入时(我想用a做TextWatcher)在EditText文本中保存到文件中(我将它保存在一个文件中).外部存储中的txt文件)

我应该onCreate在活动方法或适配器类或其他地方这样做吗？

这是一些代码

主要活动代码

 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);
    }

我的适配器代码

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",我的代码可以正常工作,滚动时不保存编辑文本的内容.如果我添加此代码,当我滚动所有关闭屏幕的editText视图,而不是回来时搞砸了内容.

Answer 1

你的解决方案的主要问题是在onBindViewHolder中分配和分配TextWatcher,这是一个昂贵的操作,会在快速滚动期间引入滞后,它似乎也会干扰确定mAdapter中要更新的位置.

在onCreateViewHolder中进行所有操作是更可取的选择.以下是完整的测试工作解决方案:

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
        }
    }
}

Answer 2

我有同样的问题,我添加了以下行,似乎已经解决了我的问题.

mRecyclerview.setItemViewCacheSize(mDataset.size());

希望这可以帮助您解决问题.

Answer 3

我实施了@dkarmazi 解决方案，但对我没有帮助。所以，我走得更远，有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 在项目回收期间继续工作。

我试图在回收之前禁用它，但没有任何“beforeRecycle”事件方法。所以我使用了onViewDetachedFromWindow方法，并且效果很好。

Answer 4

我将创建一个界面并传递当前适配器位置来处理文本更改事件

    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);
        ViewHolder vh = new ViewHolder(v, new ViewHolder.ITextWatcher() {
            @Override
            public void beforeTextChanged(int position, CharSequence s, int start, int count, int after) {
                // do something
            }

            @Override
            public void onTextChanged(int position, CharSequence s, int start, int before, int count) {
                mDataset[position] = s.toString();
            }

            @Override
            public void afterTextChanged(int position, Editable s) {
                // do something
            }
        });

        return vh;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, final int position) {
        holder.mEditText.setText(mDataset[position]);
    }

    @Override
    public int getItemCount() {
        return mDataset.length;
    }


    public static class ViewHolder extends RecyclerView.ViewHolder {

        public EditText mEditText;
        private ITextWatcher mTextWatcher;

        public interface ITextWatcher {
            // you can add/remove methods as you please, maybe you dont need this much
            void beforeTextChanged(int position, CharSequence s, int start, int count, int after);

            void onTextChanged(int position, CharSequence s, int start, int before, int count);

            void afterTextChanged(int position, Editable s);
        }

        public ViewHolder(View v, ITextWatcher textWatcher) {
            super(v);

            this.mEditText = (EditText) v.findViewById(R.id.editText);

            this.mTextWatcher = textWatcher;

            this.mEditText.addTextChangedListener(new TextWatcher() {
                @Override
                public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                    mTextWatcher.beforeTextChanged(getAdapterPosition(), s, start, count, after);
                }

                @Override
                public void onTextChanged(CharSequence s, int start, int before, int count) {
                    mTextWatcher.onTextChanged(getAdapterPosition(), s, start, before, count);
                }

                @Override
                public void afterTextChanged(Editable s) {
                    mTextWatcher.afterTextChanged(getAdapterPosition(), s);
                }
            });
        }
    }

}