我如何在活动

Question

我如何实施视图持有者？

    private class ViewHolder {
        TextView code, txtv;
        CheckBox name;
        Button btnnn;
    }

    @Override
    public View getView(final int position, View convertView,
            ViewGroup parent) {

        ViewHolder holder = null;
        Log.v("ConvertView", String.valueOf(position));

        if (convertView == null) {
            LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = vi.inflate(R.layout.abb_list, null);

            holder = new ViewHolder();
            holder.code = (TextView) convertView.findViewById(R.id.code);
            holder.name = (CheckBox) convertView
                    .findViewById(R.id.checkBox1);
            holder.btnnn = (Button) convertView.findViewById(R.id.btn);
            holder.txtv = (TextView) convertView.findViewById(R.id.txt);
            convertView.setTag(holder);

            holder.name.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    CheckBox cb = (CheckBox) v;
                    checkTable country = (checkTable) cb.getTag();
                    country.setSelected(cb.isChecked());
                }
            });
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        holder.btnnn.setOnClickListener(new OnClickListener() {

             int counter = 0;

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                counter++;

                holder.txtv.setText(String.valueOf(counter));
            }
        });

        checkTable checkTable = itemsList.get(position);
        holder.code.setText(" (" + checkTable.getitemprice() + ")");
        holder.name.setText(checkTable.getitemname());
        holder.name.setChecked(checkTable.isSelected());
        holder.name.setTag(checkTable);


        return convertView;

    }

}

当我正在holder.txtv.setText(String.valueOf(counter));时，它会向我显示错误Cannot refer to the non-final local variable holder defined in an enclosing scope建议我如何解决此问题。

Answer 1

您可以使用final TextView作为监听器：

final TextView counterTxt = holder.txtv;
holder.btnnn.setOnClickListener(new OnClickListener() {

    int counter = 0;

    @Override
    public void onClick(View v) {
        counter++;
        counterTxt.setText(String.valueOf(counter));
    }
});

Answer 2

在方法之外声明一些变量，作为私有变量：

private TextView counterTx;
private int counter;
private ViewHolder holder;

编辑：我认为这是一个更好的实现，将这些变量声明为final，因为之后您无法更改其值。

Answer 3

我建议您将 findViewById 和 View.OnClickListener 移至ViewHolder。还要在其中保留一个checkTable引用。这将使代码更清晰。

这种风格是从学到的。 RecylerView.ViewHolder旨在取代ListView，并应在未来的项目中使用。

@Override
public View getView(final int position, View convertView,
        ViewGroup parent) {

    ViewHolder holder = null;
    Log.v("ConvertView", String.valueOf(position));

    if (convertView == null) {
        LayoutInflater vi = LayoutInflater.from(parent.getContext());
        convertView = vi.inflate(R.layout.abb_list, parent, false);
        holder = new ViewHolder(convertView);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    checkTable checkTable = itemsList.get(position);
    holder.country = checkTable;
    holder.code.setText(" (" + checkTable.getitemprice() + ")");
    holder.name.setText(checkTable.getitemname());
    holder.name.setChecked(checkTable.isSelected());

    return convertView;
}

// Try to use static inner class as possible as you can, this will eliminate
// many strange issues.
private static class ViewHolder implments View.OnClickListener {
    checkTable country;
    TextView code, txtv;
    CheckBox name;
    Button btnnn;

    public ViewHolder(View view) {
        view.setTag(this);
        code = (TextView) convertView.findViewById(R.id.code);
        name = (CheckBox) convertView.findViewById(R.id.checkBox1);
        btnnn = (Button) convertView.findViewById(R.id.btn);
        txtv = (TextView) convertView.findViewById(R.id.txt);
        name.setOnClickListener(this);
        btnnn.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        if (v == btnnn) {
            // ViewHolder will be reused, you better move counter to checkTable
            checkTable.counter++;
            txtv.setText(String.valueOf(checkTable.counter));
        } else if (v == name) {
            country.setSelected(name.isChecked());
        }
    }
}