studio - android viewlist



ListView與ArrayAdapter和ViewHolder添加圖標到錯誤的項目 (2)

我有一個使用ArrayAdapter的動態ListView 。 當從微調器中選擇一個名稱時,名稱連同一個顯示是男性還是女性的圖標被添加到ListView

大多數情況下都是好的(名字被正確添加到列表中,連同一個圖標)。 但顯示性別的圖標被添加到ListView的錯誤的項目。 該名稱被添加到列表的底部,但圖標被放置在列表頂部的名稱上。 我不知道這是我使用ViewHolder的方式,但在Android網站上沒有文檔。

// 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);

Answer #1

更新: ViewHolder僅用於保存對項目佈局內部組件視圖的引用。 這有助於避免調用findViewById來渲染具有多個組件的複雜項目佈局中的每個組件(如本例中的TextViewImageView )的開銷。

我通過使用例程(稱為getSex )來檢索性別數據並設置所有包含if-else塊外的圖標的視圖數據。

工作代碼現在看起來像這樣:

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;

Answer #2

您必須在if-else-if之後設置圖標以創建或綁定holder 。 否則,只能在列表中的前幾個項目中正確顯示圖標,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;
}




android-arrayadapter