在 RecyclerView.Adapter 中使用不同的 TextWatcher 实现

Question

目前我使用RecyclerView来表示动态配置列表表单

每个配置项（RecyclerView 列表中的条目）都包含一个 EditText 项。为了避免错误的用户输入（一些字段只允许整数，其他字段只允许逗号后的一位数字），我实现了两个不同的 TextWatcher-filters 来纠正非法输入（"DecimalFilterDigitsAfterComma" 和 "DecimalFilterInteger"）。我的RecyclerView一共有16个配置项，但是一次最多只能显示8个。

我的问题是 TextWatcher 被分配给了特定的项目（整数和小数点 TextEdit）。但是当我稍微滚动一下时，它们会改变它们的顺序，这样十进制和整数过滤器就会交换。

TextWatcher 项目将在 RecyclerView.Adapter 的 ConfigurationAdapter 中创建。我已经设法通过使用 mListConfigInit 为每个条目创建一次 TextWatcher，它是项目的布尔标志列表。

ConfigurationAdapter.java:

public class ConfigurationAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    /*
    ...
    */

    private List<ConfigItem> mConfiguration = new ArrayList<>();

    // make sure that DecimalFilter is only created once for each item
    private List<Boolean> mListConfigInit = new ArrayList<>();
    public ConfigurationAdapter() {
    }


    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.listitem_configuration,
                parent,
                false);

        final ConfigurationViewHolder vh = new ConfigurationViewHolder(v);


        /*
        ...
        */

        return vh;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        final ConfigurationViewHolder vh = (ConfigurationViewHolder) holder;
        ConfigItem config = mConfiguration.get(position);

    if(config.ShowValueAsFloat()) {
        vh.SetTextWatcherType(ConfigurationViewHolder.TextWatcherType.type_FloatActive);
    } else {
        vh.SetTextWatcherType(ConfigurationViewHolder.TextWatcherType.type_IntActive);
    }


        // set name and unit
        vh.mName.setText(config.mName);
        vh.mUnit.setText(config.mUnit);

        /*
        ...
        */
    }

    @Override
    public int getItemCount() {
        return mConfiguration.size();
    }

    public void addConfigItem(ConfigItem item) {
        mConfiguration.add(item);
        mListConfigInit.add(new Boolean(false));
        notifyItemInserted(mConfiguration.size() - 1);
        //notifyDataSetChanged();
    }

    /*
    ...
    */


}

ConfigurationViewHolder.java（根据 pskink-comments 更改）：

public final class ConfigurationViewHolder extends RecyclerView.ViewHolder implements TextWatcher {
    public TextView mName;
    public CheckBox mCheckbox;
    public SeekBar mSeekbar;
    public EditText mValueEditText;
    public TextView mUnit;


    private List<TextWatcher> mListTextWatchers = new ArrayList<>();

    public enum TextWatcherType {
        type_FloatActive(0),
        type_IntActive(1);

        private int mValue;

        TextWatcherType(int value) {
            mValue = value;
        }

        int val() { return mValue; }
    }

    private TextWatcherType mTextWatcherType = TextWatcherType.type_FloatActive;

    public ConfigurationViewHolder(View itemView) {
        super(itemView);

        mName = (TextView) itemView.findViewById(R.id.textView_configuration_name);
        mValueEditText = (EditText) itemView.findViewById(R.id.editText_configuration_value);
        mUnit = (TextView) itemView.findViewById(R.id.textView_configuration_unit);
        mCheckbox = (CheckBox) itemView.findViewById(R.id.checkbox_configuration);
        mSeekbar = (SeekBar) itemView.findViewById(R.id.seekBar_configuration);

        mListTextWatchers.add(0, new DecimalFilterDigitsAfterComma(mValueEditText, 1));
        mListTextWatchers.add(1, new DecimalFilterInteger(mValueEditText));
        mValueEditText.addTextChangedListener(this);
    }

    public void SetTextWatcherType(TextWatcherType textWatcherType) {
        mTextWatcherType = textWatcherType;
    }

    @Override
    public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {}

    @Override
    public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {}

    @Override
    public void afterTextChanged(Editable editable) {
        mListTextWatchers.get(mTextWatcherType.val()).afterTextChanged(editable);
    }
}

DecimalFilterInteger.java

public class DecimalFilterInteger implements TextWatcher {
    private final static String TAG = ConfigurationAdapter.class.getSimpleName();
    private final EditText mEditText;
    private String mLastTextValue = new String("");

    public DecimalFilterInteger(EditText editText) {
        this.mEditText = editText;
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }

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

    @Override
    public synchronized void afterTextChanged(final Editable text) {
        String strInput = text.toString().trim();
        if(strInput.isEmpty()) {
            return;
        }

        if(strInput.equals(mLastTextValue)) {   // return when same value as last time to avoid endless loop
            return;
        }

        if ((strInput.charAt(0) == '.')) {  // handle dot at beginning
            strInput = "";
        }

        if(strInput.contains(".")){         // cut trailing comma
            String numberBeforeDecimal = strInput.split("\.")[0];
            strInput = numberBeforeDecimal;
        }
        mEditText.removeTextChangedListener(this);

        mEditText.getText().clear();    // do not use setText here to avoid changing the keyboard
        mEditText.append(strInput);     // back to default (e. g. from 123-mode to abc-mode),
                                        // see: 
        mLastTextValue = mEditText.getText().toString();

        mEditText.setSelection(mEditText.getText().toString().trim().length());
        mEditText.addTextChangedListener(this);
    }
}

非常感谢您的帮助！

Answer 1

RecyclerView 中两个不同的 TextWatcher 实现的 swap/switching 行为的原因是我在它们的 afterTextChanged 方法中调用了 removeTextChangedListener 和 addTextChangedListener 来避免重新触发 afterTextChanged 方法。

避免重新触发的最佳方法是简单地检查文本自上次调用后是否更改：

public class DecimalFilterInteger implements TextWatcher {
    private final static String TAG = ConfigurationAdapter.class.getSimpleName();
    private final EditText mEditText;
    private String mLastTextValue = new String("");

    // ...

    @Override
    public synchronized void afterTextChanged(final Editable text) {
        String strInput = text.toString().trim();
        if(strInput.isEmpty()) {
            return;
        }

        if(strInput.equals(mLastTextValue)) {   // return when same value as last time to avoid endless loop
            return;
        }

        if ((strInput.charAt(0) == '.')) {  // handle dot at beginning
            strInput = "";
        }

        if(strInput.contains(".")){         // cut trailing comma
            String numberBeforeDecimal = strInput.split("\.")[0];
            strInput = numberBeforeDecimal;
        }
        //mEditText.removeTextChangedListener(this);    // CAUSE OF SWAP-ERROR !!!

        mEditText.getText().clear();    // do not use setText here to avoid changing the keyboard
        mEditText.append(strInput);     // back to default (e. g. from 123-mode to abc-mode),
                                        // see: 
        mLastTextValue = mEditText.getText().toString();

        mEditText.setSelection(mEditText.getText().toString().trim().length());
        //mEditText.addTextChangedListener(this);       // CAUSE OF SWAP-ERROR !!!
    }
}

在 RecyclerView.Adapter 中使用不同的 TextWatcher 实现

Use of different TextWatcher-implementations inside RecyclerView.Adapter

android

adapter

textwatcher

android-recyclerview