Question

看起来有两种方法可以更改ListView行中的内容：

使用setViewBinder / setViewValue：

myCursor.setViewBinder（new SimpleCursorAdapter.ViewBinder（）{

  @Override
  public boolean setViewValue(View view, Cursor cursor, int columnIndex) {
    int viewId = view.getId();
    switch(viewId) {
    case R.id.icon:
        // change something related to the icon here

使用getView / LayoutInflater：

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

    View itemView = null;

    if (convertView == null) {
        LayoutInflater inflater = (LayoutInflater) parent.getContext()
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        itemView = inflater.inflate(R.layout.list_row, null);
    } else {
        itemView = convertView;
    }

    ImageView imgViewChecked = (ImageView) itemView
            .findViewById(R.id.icon);
    // change something related to the icon here

这两种方法有什么区别？

Answer 1

您可以同时使用它们来完成相同的任务。 ViewCinder系统由SimpleCursorAdapter添加，使您更轻松，因此您不必编写整个getView代码。实际上，SimpleCursorAdapter只是通过调用setViewValue方法（以及标准样板错误检查和膨胀）来实现getView。

我已经附加了Android源代码在SimpleCursorAdapter中用于getView的实现：

public View getView(int position, View convertView, ViewGroup parent) {
  if (!mDataValid) {
    throw new IllegalStateException(
        "this should only be called when the cursor is valid");
  }
  if (!mCursor.moveToPosition(position)) {
    throw new IllegalStateException("couldn't move cursor to position "
        + position);
  }
  View v;
  if (convertView == null) {
    v = newView(mContext, mCursor, parent);
  } else {
    v = convertView;
  }
  bindView(v, mContext, mCursor);
  return v;
}


public void bindView(View view, Context context, Cursor cursor) {
  final ViewBinder binder = mViewBinder;
  final int count = mTo.length;
  final int[] from = mFrom;
  final int[] to = mTo;

  for (int i = 0; i < count; i++) {
    final View v = view.findViewById(to[i]);
    if (v != null) {
      boolean bound = false;
      if (binder != null) {
        bound = binder.setViewValue(v, cursor, from[i]);
      }

      if (!bound) {
        String text = cursor.getString(from[i]);
        if (text == null) {
          text = "";
        }

        if (v instanceof TextView) {
          setViewText((TextView) v, text);
        } else if (v instanceof ImageView) {
          setViewImage((ImageView) v, text);
        } else {
          throw new IllegalStateException(
              v.getClass().getName()
                  + " is not a "
                  + " view that can be bounds by this SimpleCursorAdapter");
        }
      }
    }
  }
}

setViewBinder / setViewValue和getView / LayoutInflater的用法有什么区别？

1 个答案: