从自定义适配器获取Hashmap项(Get Hashmap item from custom adapter)

我是否知道如何从自定义适配器获取HashMap项目

码：

ArrayList<HashMap<String, String>> feeds_List; ... ... HashMap<String, String> map = new HashMap<String, String>(); // adding each child node to HashMap key => value map.put("username", usr_name); map.put("datetime", feed_date); map.put("pts", point_txt); map.put("pic", pic); // adding HashList to ArrayList feeds_List.add(map); ListAdapter adapter = new ExtendedSimpleAdapter( getActivity(), feeds_List, R.layout.feed_item, new String[]{"username", "datetime", "pts"}, new int[]{R.id.usr_name, R.id.feed_time, R.id.no_stamp}); setListAdapter(adapter);

我的定制适配器：

public class ExtendedSimpleAdapter extends SimpleAdapter{ Context context2; public ExtendedSimpleAdapter(Context context, List<? extends Map<String, String>> data, int resource, String[] from, int[] to){ super(context, data, resource, from, to); context2=context; } public View getView(int position, View convertView, ViewGroup parent){ // here you let SimpleAdapter built the view normally. View v = super.getView(position, convertView, parent); // Then we get reference for Picasso ImageView img = (ImageView) v.getTag(); if(img == null){ img = (ImageView) v.findViewById(R.id.usr_pic); v.setTag(img); // <<< THIS LINE !!!! } // get the url from the data you passed to the `Map` String TAG_IMAGE="pic"; String url = ((Map)getItem(position)).get("pic"); // do Picasso // maybe you could do that by using many ways to start Picasso.with(context2) .load(url) //.resize(100, 100) .into(img); // return the view return v; } }

这是问题所在：

我无法在自定义适配器中获取url字符串。总是得到错误

“不兼容的类型”（需要String，但找到的是对象）

这条线

String url = ((Map)getItem(position)).get("pic");

May i know how to get HashMap item from a custom adapter

Code:

ArrayList<HashMap<String, String>> feeds_List; ... ... HashMap<String, String> map = new HashMap<String, String>(); // adding each child node to HashMap key => value map.put("username", usr_name); map.put("datetime", feed_date); map.put("pts", point_txt); map.put("pic", pic); // adding HashList to ArrayList feeds_List.add(map); ListAdapter adapter = new ExtendedSimpleAdapter( getActivity(), feeds_List, R.layout.feed_item, new String[]{"username", "datetime", "pts"}, new int[]{R.id.usr_name, R.id.feed_time, R.id.no_stamp}); setListAdapter(adapter);

My Custom Adapter:

public class ExtendedSimpleAdapter extends SimpleAdapter{ Context context2; public ExtendedSimpleAdapter(Context context, List<? extends Map<String, String>> data, int resource, String[] from, int[] to){ super(context, data, resource, from, to); context2=context; } public View getView(int position, View convertView, ViewGroup parent){ // here you let SimpleAdapter built the view normally. View v = super.getView(position, convertView, parent); // Then we get reference for Picasso ImageView img = (ImageView) v.getTag(); if(img == null){ img = (ImageView) v.findViewById(R.id.usr_pic); v.setTag(img); // <<< THIS LINE !!!! } // get the url from the data you passed to the `Map` String TAG_IMAGE="pic"; String url = ((Map)getItem(position)).get("pic"); // do Picasso // maybe you could do that by using many ways to start Picasso.with(context2) .load(url) //.resize(100, 100) .into(img); // return the view return v; } }

Here is the problem:

I cannot get the url string in the custom adapter. always getting errors of

"Incompatible types"(needed String, but found is object)

for this line

String url = ((Map)getItem(position)).get("pic");

最满意答案

您要反对的对象应该具有确切的类型。转换为通用Map不会强制执行编译时检查，这是泛型的意思。

String url = ((Map<String, String>)getItem(position)).get("pic");

The object you are casting against, should have the exact type. Casting to the generic Map doesn't enforce the compile time check, that the generics are meant for.

String url = ((Map<String, String>)getItem(position)).get("pic");

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