Question

我想做什么 ::我正在尝试使用Commonsware无限的适配器功能
我做了什么 ::我跟踪了here中的所有文档并提出了我的计划
正在发生的事情 ::我收到了如图所示的日志错误

MainActivity.java

public class MainActivity extends ListActivity {

    private LinkedList<LinkedHashMap<String, String>> messengerListObject;
    private LinkedHashMap<String, String> messengerMapObject;

    static int LIST_SIZE;
    private int mLastOffset = 0;

    static final int BATCH_SIZE = 5;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        addDataForCollection();
        init();

    }

    private void setLastOffset(int i) {
        mLastOffset = i;  
    }

    private int getLastOffset(){
        return mLastOffset;
    }

    private void init() {

        //Store the array size in a variable
        LIST_SIZE = messengerListObject.size();
        //Load the first 10 elements from the array
        for (int i=0; i<=BATCH_SIZE; i++){
            messengerMapObject=messengerListObject.get(i);
        }
        setLastOffset(BATCH_SIZE);
        displayList(messengerMapObject);
    }

    private void displayList(LinkedHashMap<String, String> messengerMapObject) {  
        setListAdapter(new DemoAdapter());
    }


    class DemoAdapter extends EndlessAdapter {
        private RotateAnimation rotate=null;
        LinkedList<LinkedHashMap<String, String>> tempList=new LinkedList<LinkedHashMap<String, String>>();
        DemoAdapter() {
            super(new AdapterMain(MainActivity.this, messengerMapObject));

            rotate=new RotateAnimation(0f, 360f, Animation.RELATIVE_TO_SELF,
                    0.5f, Animation.RELATIVE_TO_SELF,
                    0.5f);
            rotate.setDuration(600);
            rotate.setRepeatMode(Animation.RESTART);
            rotate.setRepeatCount(Animation.INFINITE);
        }

        @Override
        protected View getPendingView(ViewGroup parent) {
            View row=getLayoutInflater().inflate(R.layout.row, null);

            View child=row.findViewById(android.R.id.text1);
            child.setVisibility(View.GONE);
            child=row.findViewById(R.id.throbber);
            child.setVisibility(View.VISIBLE);
            child.startAnimation(rotate);

            return(row);
        }

        @Override
        protected boolean cacheInBackground() {
            tempList.clear();
            int lastOffset = getLastOffset();
            if(lastOffset < LIST_SIZE){
                int limit = lastOffset + BATCH_SIZE;
                for(int i=(lastOffset+1); (i<=limit && i<LIST_SIZE); i++){
                    tempList.add(messengerListObject.get(i));
                }    
                setLastOffset(limit);

                if(limit<LIST_SIZE){
                    return true;
                } else {
                    return false;
                }
            } else  {
                return false;
            }
        }


        @Override
        protected void appendCachedData() {

            @SuppressWarnings("unchecked")
            LinkedList<LinkedHashMap<String, String>> arrAdapterNew = (LinkedList<LinkedHashMap<String, String>>)getWrappedAdapter();

            int listLen = tempList.size();
            for(int i=0; i<listLen; i++){
                arrAdapterNew.add(tempList.get(i));
            }
        }
    }


    private void addDataForCollection() {
        messengerListObject=new LinkedList<LinkedHashMap<String, String>>();
        for(int i=1;i<100;i++){
            messengerMapObject=new LinkedHashMap<String, String>();
            messengerMapObject.put("android", "Android-"+i+"");
            messengerListObject.add(messengerMapObject);
        }
    }
}

AdapterMain.java

public class AdapterMain extends BaseAdapter {

    private Context mContext=null;
    private HashMap<String, String> messengerMapObject;

    public AdapterMain(Context context, LinkedHashMap<String, String> _messengerMapObject) {
        super();
        mContext = context;
        messengerMapObject=_messengerMapObject;
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return 0;
    }


    class ViewHolder {
        public TextView txtTitle;

        public ViewHolder(View base) {
            txtTitle = (TextView) base.findViewById(R.id.txtTitle);
        }
    }

    public View getView(int position, View convertView, ViewGroup parent) {

        View view = convertView;  
        ViewHolder vHolder;  

        if (convertView == null) {  
            LayoutInflater layout = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);  
            view = layout.inflate(R.layout.adapter, null);  
            vHolder = new ViewHolder(view);  
            view.setTag(vHolder);  
        } else {  
            vHolder = (ViewHolder) view.getTag();  
        } 

        vHolder.txtTitle.setText(messengerMapObject.get("android"));

        return view;
    }

}

日志 ::

08-05 11:31:30.976: E/AndroidRuntime(19968): FATAL EXCEPTION: main
08-05 11:31:30.976: E/AndroidRuntime(19968): java.lang.ClassCastException: com.example.endlessadapter.AdapterMain cannot be cast to java.util.LinkedList
08-05 11:31:30.976: E/AndroidRuntime(19968):    at com.example.endlessadapter.MainActivity$DemoAdapter.appendCachedData(MainActivity.java:113)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at com.commonsware.cwac.endless.EndlessAdapter$AppendTask.onPostExecute(EndlessAdapter.java:343)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at com.commonsware.cwac.endless.EndlessAdapter$AppendTask.onPostExecute(EndlessAdapter.java:1)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at android.os.AsyncTask.finish(AsyncTask.java:602)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at android.os.AsyncTask.access$600(AsyncTask.java:156)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at android.os.Looper.loop(Looper.java:137)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at android.app.ActivityThread.main(ActivityThread.java:4340)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at java.lang.reflect.Method.invokeNative(Native Method)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at java.lang.reflect.Method.invoke(Method.java:511)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
08-05 11:31:30.976: E/AndroidRuntime(19968):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

我认为你的问题在这里：

这是Commonsware无限的Adapter构造函数的定义：

public EndlessAdapter(Context ctx, List<String> itemList, int layoutId)

但你发送给它

 super(new AdapterMain(MainActivity.this, messengerMapObject));

哪个

private LinkedHashMap<String, String> messengerMapObject;

Answer 2

您还可以查看SuperListView库的代码。

SuperListView支持无限滚动。见https://github.com/dommerq/SuperListview

在Android中使用Endless Adapter for listview

2 个答案: