我是android的新手,我花了最近2天尝试前面的例子和在线解决方案,但我似乎无法理解它:(
我能够显示列表视图,从在线解析一些json并存储书名,书籍描述和书籍ID,并在列表视图中显示这些数据.我希望能够在ListView的每一行中放置一个“下载”按钮,每个按钮将对应于Click()上的书籍ID,动作监听器将通过将该ID附加到URL来下载该书.
例如www.books.com/download_book1或/ download_book2 ….
public class Catalogue extends ListActivity {
private JSONObject json;
private ListView lv;
private ArrayList<Integer> alKey = new ArrayList<Integer>();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); //icicle
setContentView(R.layout.shelflist);
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
....
try{
JSONArray entries = json.getJSONArray("entries");
for(int i=0;i<entries.length();i++){
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = entries.getJSONObject(i);
alKey.add(e.getInt("key"));
map.put("id", String.valueOf(i));
map.put("title", "Title:" + e.getString("title"));
map.put("description", "Description: " + e.getString("description"));
mylist.add(map);
}
}catch(JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
listadapter adapter = new SimpleAdapter(this, mylist , R.layout.shelfrow,
new String[] { "title", "description" },
new int[] { R.id.item_title, R.id.item_subtitle });
setlistadapter(adapter);
lv = getListView();
lv.setTextFilterEnabled(true);
…..
这是我得到的.我不知道如何在List中每行添加1个按钮,并为每个按钮分配一个动作监听器.
我还有一个shelfrow.xml文件(textView,textView for item_title和item_subtitle)和一个shelflist.xml文件(ListView).
我有一个shelf.xml文件
解决方法:
基本上你需要学习ListAdapter的概念.
这是一个短篇小说:图片中包含要在列表中显示的数据的对象,以及单独显示每一行的方式.这是你的listadapter.现在拿出每一行:它是一本带有标题和OnClickListener的书.它在带有TextView(用于标题)和Button(用于OnClickListener)的View中呈现.您需要做的就是将一个View提供给将用于每一行的适配器,以及一个要列在列表中的书籍列表.
private class MyItemmodel{ //that's our book
String title; // the book's title
String description;
long id;
OnClickListener listener = new OnClickListener(){ // the book's action
@Override
public void onClick(View v) {
// the default action for all lines
doSomethingWithTheBookTitleOrUniqueId(this);
}
};
}
private class Mylistadapter extends BaseAdapter{
View renderer;
List<MyItemmodel> items;
// call this one and pass it layoutInflater.inflate(R.layout.my_list_item)
public Mylistadapter(View renderer) {
this.renderer = renderer;
}
// whenever you need to set the list of items just use this method.
// call it when you have the data ready and want to display it
public void setModel(List<MyItemmodel> items){
this.items = items;
notifyDataSetChanged();
}
@Override
public int getCount() {
return items!=null?items.size():0;
}
@Override
public Object getItem(int position) {
return items!=null?items.get(position):null;
}
@Override
public long getItemId(int position) {
return items!=null?items.get(position).id:-1;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView==null){
convertView = renderer;
}
MyItemmodel item = items.get(position);
// replace those R.ids by the ones inside your custom list_item layout.
TextView label = (TextView)convertView.findViewById(R.id.item_title);
label.setText(item.label);
Button button = (Button)convertView.findViewById(R.id.item_button);
button.setonClickListener(item.listener);
return convertView;
}
}
为了传递List,而不是将数据放在你的hashmaps列表中,你可以这样做(小心,我也根据你的需要更新了MyItemmodel和Mylistadapter,添加了id和description属性):
List<MyItemmodel> myListModel = new ArrayList<MyItemmodel>();
try{
JSONArray entries = json.getJSONArray("entries");
for(int i=0;i<entries.length();i++){
MyItemmodel item = new MyItemmodel();
JSONObject e = entries.getJSONObject(i);
alKey.add(e.getInt("key"));
item.id = i;
item.title = e.getString("title");
item.description = e.getString("description");
// you can change the button action at this point:
// item.onClickListener = new OnClickListener(){...};
myListModel.add(item);
}
}catch(JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
listadapter adapter = new Mylistadapter(getLayoutInflater().inflate(R.layout.shelfrow, this));
adapter.setModel(myListModel);
setlistadapter(adapter);
lv = getListView();
lv.setTextFilterEnabled(true);
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