带有ArrayAdapter和ViewHolder的ListView将图标添加到错误的项目中
我有一个使用ArrayAdapter的动态ListView 。 当从微调器中选择一个名称时，该名称以及显示它们是男性还是女性的图标将被添加到ListView 。
大多数情况下都很好（名称会正确添加到列表中，并附带一个图标）。 但是显示性别的图标被添加到ListView的错误项目中。 该名称被添加到列表的底部，但该图标被放置在列表顶部的名称处。 我不知道这是我使用ViewHolder的方式，但是Android网站上没有文档。
// Listview inflater
inflater = (LayoutInflater) (this).getSystemService(LAYOUT_INFLATER_SERVICE);
// List Array.
mAdapter = new ArrayAdapter<String>(this, R.layout.player_simple_list,
R.id.label, mStrings) {
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Log.i("ANDY","View getView Called");
// A ViewHolder keeps references to children views to
// avoid unneccessary calls to findViewById() on each row.
ViewHolder holder;
if (null == convertView) {
Log.i("ANDY","Position not previously used, so inflating");
convertView = inflater.inflate(R.layout.player_simple_list, null);
// Creates a ViewHolder and store references to the
// two children views we want to bind data to.
holder = new ViewHolder();
holder.text = (TextView) convertView.findViewById(R.id.label);
holder.icon = (ImageView) convertView.findViewById(R.id.icon);
if (sexmale == true) {
holder.icon.setImageBitmap(maleicon);
}
else {
holder.icon.setImageBitmap(femaleicon);
}
convertView.setTag(holder);
} else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}
// Bind the data efficiently with the holder.
holder.text.setText(getItem(position));
// Change icon depending is the sexmale variable is true or false.
Log.i("ANDY","getCount = "+mAdapter.getCount());
return convertView;
}
};
setListAdapter(mAdapter);
您必须在if-else-if之后设置图标以创建或绑定holder 。 否则，这些图标只能在列表中的前几个项目中正确显示，即直到ListView未被填充。
public View getView(int position, View convertView, ViewGroup parent) {
Log.i("ANDY","View getView Called");
// A ViewHolder keeps references to children views
// to avoid unneccessary calls to findViewById() on each row.
ViewHolder holder;
if (null == convertView) {
Log.i("ANDY","Position not previously used, so inflating");
convertView = inflater.inflate(R.layout.player_simple_list, null);
// Creates a ViewHolder and store references to
// the two children views we want to bind data to.
holder = new ViewHolder();
holder.text = (TextView) convertView.findViewById(R.id.label);
holder.icon = (ImageView) convertView.findViewById(R.id.icon);
convertView.setTag(holder);
} else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}
// Bind the data efficiently with the holder.
holder.text.setText(getItem(position));
// Change icon depending is the sexmale variable is true or false.
if (sexmale == true) {
holder.icon.setImageBitmap(maleicon);
}
else {
holder.icon.setImageBitmap(femaleicon);
}
Log.i("ANDY","getCount = "+mAdapter.getCount());
return convertView;
}
如果在评论之后有几行数据，就必须从这个数据移开，就像在这个问题中所解释的那样
// Bind the data efficiently with the holder.
所以它会看起来像这样
if (null == convertView) {
Log.i("ANDY","Position not previously used, so inflating");
convertView = inflater.inflate(R.layout.player_simple_list, null);
// Creates a ViewHolder and store references to the two children views
// we want to bind data to.
holder = new ViewHolder();
convertView.setTag(holder);
} else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}
// Bind the data efficiently with the holder.
holder.text = (TextView) convertView.findViewById(R.id.label);
holder.icon = (ImageView) convertView.findViewById(R.id.icon);
if (sexmale == true) {
holder.icon.setImageBitmap(maleicon);
}
else {
holder.icon.setImageBitmap(femaleicon);
}
holder.text.setText(getItem(position));
更新： ViewHolder仅用于保存对项目布局内部组件视图的引用。 这有助于避免调用findViewById来渲染具有多个组件的复杂项目布局中的每个组件（如本例中的TextView和ImageView ）的开销。
我通过使用例程（称为getSex ）来检索性别数据并设置所有视图数据，包括if-else块外部的图标。
工作代码现在看起来像这样：
if (null == convertView) {
Log.i("ANDY","Position not previously used, so inflating");
convertView = inflater.inflate(R.layout.player_simple_list, null);
// Creates a ViewHolder and store references to the two children views
// we want to bind data to.
holder = new ViewHolder();
holder.text = (TextView) convertView.findViewById(R.id.label);
holder.icon = (ImageView) convertView.findViewById(R.id.icon);
convertView.setTag(holder);
} else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}
// Bind the data efficiently with the holder.
holder.text.setText(getItem(position));
// Change icon depending is the sexmale variable is true or false.
if (getSex (getItem(position)) == true) {
holder.icon.setImageBitmap(maleicon);
}
else {
holder.icon.setImageBitmap(femaleicon);
}
return convertView;
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