问题描述

lazyadapter 列表视图

我想把 ListView 中 selected item 的值传递到另一个 activity 中。
我用下面的代码获取 hashmap 的相关细节，但是却获得 java.lang.Integer cannot be cast to java.util.HashMap 错误。

public void onItemClick(AdapterView<?> parent View view                    int position long id) {                HashMap<String String> o = (HashMap<String String>) list.getItemAtPosition(position);                Toast.makeText(CustomizedListView.thisID '"" + o.get(""KEY_TITLE"") + ""' was clicked."" Toast.LENGTH_SHORT).show();             }     

如何修改呢？

public class CustomizedListView extends Activity {    // All static variables    static final String URL = ""https://itunes.apple.com/us/rss/topalbums/limit=20/json"";    // XML node keys    static final String KEY_SONG = ""song""; // parent node    static final String KEY_ID = ""id"";    static final String KEY_TITLE = ""title"";    static final String KEY_ARTIST = ""artist"";    static final String KEY_DURATION = ""duration"";    static final String KEY_THUMB_URL = ""thumb_url"";    ListView list;    LazyAdapter adapter;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        ArrayList<HashMap<String String>> songsList = new ArrayList<HashMap<String String>>();        JSONObject json = JSONfunctions.getJSONfromURL(URL);        try {            JSONObject arr2 = json.getJSONObject(""feed"");            JSONArray arr = arr2.getJSONArray(""entry"");            for (int i = 0; i < arr.length(); i++) {                JSONObject e1 = arr.getJSONObject(i);                JSONArray arr3 = e1.getJSONArray(""im:image"");                JSONObject arr8 = e1.getJSONObject(""im:name"");                JSONObject arr10 = e1.getJSONObject(""im:artist"");                    JSONObject e12 = arr3.getJSONObject(0);            // creating new HashMap            HashMap<String String> map = new HashMap<String String>();            map.put(KEY_THUMB_URL  e12.getString(""label""));            map.put(KEY_ARTIST arr8.getString(""label""));            map.put(KEY_TITLE arr10.getString(""label""));            // adding HashList to ArrayList            songsList.add(map);            }        } catch (JSONException e) {            // Log.e(""log_tag""Error parsing data ""+e.toString());            Toast.makeText(getBaseContext()Network communication error!"" 5).show();        }        list=(ListView)findViewById(R.id.list);        // Getting adapter by passing xml data ArrayList        adapter=new LazyAdapter(this songsList);                list.setAdapter(adapter);        // Click event for single list row        list.setOnItemClickListener(new OnItemClickListener() {            @SuppressWarnings(""unchecked"")            @Override            public void onItemClick(AdapterView<?> parent View view                    int position long id) {                HashMap<String String> o = (HashMap<String String>) list.getItemAtPosition(position);                Toast.makeText(CustomizedListView.thisID '"" + o.get(""KEY_TITLE"") + ""' was clicked."" Toast.LENGTH_SHORT).show();             }        });         }   }

但是下面的同样的代码可以运行，这是为什么呢？
这个例子中是 SimpleAdapter

public class Main extends ListActivity {    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.listplaceholder);        ArrayList<HashMap<String String>> mylist = new ArrayList<HashMap<String String>>();        JSONObject json = JSONfunctions.getJSONfromURL(""http://api.geonames.org/earthquakesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&username=demo"");        try{            JSONArray  earthquakes = json.getJSONArray(""earthquakes"");            for(int i=0;i<earthquakes.length();i++){                                        HashMap<String String> map = new HashMap<String String>();                    JSONObject e = earthquakes.getJSONObject(i);                map.put(""id""  String.valueOf(i));                map.put(""name""Earthquake name:"" + e.getString(""eqid""));                map.put(""magnitude""Magnitude: "" +  e.getString(""magnitude""));                mylist.add(map);                        }               }catch(JSONException e)        {             Log.e(""log_tag""Error parsing data ""+e.toString());        }        ListAdapter adapter = new SimpleAdapter(this mylist  R.layout.main                         new String[] { ""name""magnitude"" }                         new int[] { R.id.item_title R.id.item_subtitle });        setListAdapter(adapter);        final ListView lv = getListView();        lv.setTextFilterEnabled(true);          lv.setOnItemClickListener(new OnItemClickListener() {            public void onItemClick(AdapterView<?> parent View view int position long id) {                              @SuppressWarnings(""unchecked"")                HashMap<String String> o = (HashMap<String String>) lv.getItemAtPosition(position);                                   Toast.makeText(Main.thisID '"" + o.get(""id"") + ""' was clicked."" Toast.LENGTH_SHORT).show();             }        });    }}

解决方案

LazyAdapter 里面的getItem()方法的具体内容贴出， 看了你的代码觉得是Adapter里面有问题 而且有可能是getItem(int position)方法有问题