在RecyclerView.Adapter内部使用不同的TextWatcher实现

Question

当前，我使用RecyclerView表示动态配置列表表单。

每个配置项目（在RecyclerView列表中输入）都包含一个EditText项目。 为了避免错误的用户输入（某些字段仅允许整数，其他字段仅允许逗号后一位），我实现了两个不同的TextWatcher过滤器，它们可以纠正非法输入（“ DecimalFilterDigitsAfterComma”和“ DecimalFilterInteger”）。 我的RecyclerView总共有16个配置项，但一次最多只能显示8个。

我的问题是TextWatchers被分配给特定的项（整数和小数点TextEdit）。 但是，当我滚动一点时，它们会更改顺序，以便交换十进制过滤器和整数过滤器。

TextWatcher项将在ConfigurationAdapter内创建，后者是RecyclerView.Adapter。 我已经通过使用mListConfigInit为项目的布尔标志列表为每个条目创建一次TextWatcher进行了事件管理。

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注释进行了更改）：

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: http://stackoverflow.com/questions/26365808/edittext-settext-changes-the-keyboard-type-to-default-from-123-to-abc
        mLastTextValue = mEditText.getText().toString();

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

在此先感谢您的帮助！

Answer 1

RecyclerView内部两个不同TextWatcher实现的交换/切换行为的原因是，我在其afterTextChanged方法内部调用了removeTextChangedListener和addTextChangedListener以避免重新触发afterTextChanged方法。

避免重新触发的最佳方法是简单检查文本是否自上次调用以来已更改：

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: http://stackoverflow.com/questions/26365808/edittext-settext-changes-the-keyboard-type-to-default-from-123-to-abc
        mLastTextValue = mEditText.getText().toString();

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