Question

为什么我收到以下错误：

java.lang.String cannot be cast to java.util.HashMap

当我选择一个微调器值？

这是我的代码：

ArrayAdapter<String> spinner = new ArrayAdapter<String>(Games.this, layout.simple_spinner_dropdown_item, list1);
spinner1.setAdapter(spinner);
spinner1.setSelection(0);
spinner1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        Intent intent = null;
        switch (position) {
            case 1:
                intent = new Intent(getApplication(), Basketball.class);
                HashMap map =(HashMap)parent.getItemAtPosition(position);
                String s_id = map.get(Config.TAG_s_id).toString();
                String s_name = map.get(Config.TAG_s_name).toString();
                String s_gender = map.get(Config.TAG_s_gender).toString();
                intent.putExtra(Config.s_id,s_id);
                intent.putExtra(Config.s_name,s_name);
                intent.putExtra(Config.s_gender,s_gender);
                startActivity(intent);
                break;
                ...
         }
     }
});

这是我的logcat：

java.lang.ClassCastException: java.lang.String cannot be cast to java.util.HashMap                   
    at com.example.abe.ateneofiesta.Games$1.onItemSelected(Games.java:277)
    at android.widget.AdapterView.fireOnSelected(AdapterView.java:924)
    at android.widget.AdapterView.dispatchOnItemSelected(AdapterView.java:913)
    at android.widget.AdapterView.-wrap1(AdapterView.java)
    at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:883)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

检索微调器的值

try
        {
            URL url = new URL (Config.URL_SPIN);
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            is = httpURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
            StringBuilder sb = new StringBuilder();
            while((line = bufferedReader.readLine()) != null)
            {
                sb.append(line + "\n");
            }
            is.close();
            result = sb.toString();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try
        {
            JSONArray JA = new JSONArray(result);
            JSONObject json;
            s_name = new String[JA.length()];
            s_gender = new String[JA.length()];

            for(int i = 0; i<JA.length(); i++)
            {
                json        =  JA.getJSONObject(i);
                s_gender[i] =  json.getString("s_gender");
                s_name[i]   =  json.getString("s_name");
            }
            list1.add("All");
            for(int i = 0; i<s_name.length; i++)
            {
                list1.add(s_name[i] + " "+s_gender[i]);
            }



        } catch (JSONException e) {
            e.printStackTrace();
        }
        spinner_fn();

    }

Answer 1

ArrayAdapter<String> spinner

一旦你声明了，你永远不会通过adapter.getItemAtPosition（int）获得HashMap的实例，它将返回一个instanceof String

Answer 2

parent.getItemAtPosition(position)返回String，因为您的适配器的类型为String。如果您需要此功能，请更改为ArrayAdapter<Hashmap>。

Answer 3

您的微调器使用字符串arraylist填充..因此您无法接收Hashmap 在onItemSelected期间

试试这个：

//Declare hashmap globally
HashMap<Integer,String> haspMap_name = new HashMap<Integer, String>();
HashMap<Integer,String>  = new HashMap<Integer, String>();

现在填充Hashmap使用：

 for(int i = 0; i<JA.length(); i++)
{
    json        =  JA.getJSONObject(i);
    s_gender[i] =  json.getString("s_gender");
    s_name[i]   =  json.getString("s_name");
    haspMap_gender.put(i,s_gender[i]);
    haspMap_name.put(i,s_name[i]);
}

for(int i = 0; i<s_name.length; i++)
{
    list1.add(s_name[i] + " "+s_gender[i]);
}

在onItemSelected期间使用..

检索值

public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
    Intent intent = null;
    switch (position) {
        case 1:
            intent = new Intent(getApplication(), Basketball.class);

            String spinner_name = parent.getItemAtPosition(position).toString();
            String s_name = haspMap_name.get(position);
            String s_gender = haspMap_gender.get(position);

            //intent.putExtra(Config.s_id,s_id);
            intent.putExtra(Config.s_name,s_name);
            intent.putExtra(Config.s_gender,s_gender);
            startActivity(intent);
            break;
            ...
     }

字符串无法在Spinner项目选择上强制转换HashMap

3 个答案: