Question

嘿，我有一个listview，我使用asynctask从资源加载并在加载列表之前显示进度条。

目前，进度条在开始时不会显示，也会打破列表。任何帮助将不胜感激，通过打破列表我的意思是它加载元素在这样的彼此之上而不是一次10个元素，这在包括异步任务之前工作正常。

活动代码：

public class MovieRatingsActivity extends ListActivity
{
 private ArrayList<Movie> movies = new ArrayList<Movie>();
 private LayoutInflater mInflater;


/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    initializeUI();
}

private void initializeUI()
{
    new LoadList().execute();
}

public class LoadList extends AsyncTask<Void,Void,ArrayList<Movie>>{
    ProgressDialog loading = null;
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        try {
            loading = new ProgressDialog(getApplicationContext());
            loading.setCancelable(true);
            loading.setMessage("Loading Data...");
            loading.setIndeterminate(true);
            loading.setProgressStyle(ProgressDialog.STYLE_SPINNER);
            loading.show();
        }
        catch(Exception e){
        Log.d(TAG, "Exception: >> "+e.toString());
        }
    }

    @Override
    protected ArrayList<Movie> doInBackground(Void... aVoid){
        InputStream inputStream = getResources().openRawResource(
                R.raw.ratings);
        movies = Movie.loadFromFile(inputStream);

        return movies;
    }
    @Override
    protected void onPostExecute(ArrayList<Movie> movies) {
        super.onPostExecute(movies);
        loading.hide();
        mInflater = (LayoutInflater) getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        setListAdapter(new RowIconAdapter(getApplicationContext(), R.layout.listrow, R.id.row_label, movies));
    }
}

//declare a static holder class
public static class ViewHolder{
    ImageView icon;
    TextView movieText,votesText;
}

/** Custom row adatper -- that displays an icon next to the movie name */
class RowIconAdapter extends ArrayAdapter<Movie> 
{
    private ArrayList<Movie> movies;        
    public RowIconAdapter(Context c, int rowResourceId, int textViewResourceId, 
            ArrayList<Movie> items)
    {
        super(c, rowResourceId, textViewResourceId, items);
        movies  = items;
    }

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

        //declare a holder object
        ViewHolder holder;
        Movie currMovie = movies.get(pos);

        //nly inflate view once and get all the views once
        if (convertView == null)
        {
            convertView = mInflater.inflate(R.layout.listrow, parent, false);
            holder = new ViewHolder();
            holder.icon = (ImageView) convertView.findViewById(R.id.row_icon);
            holder.movieText = (TextView) convertView.findViewById(R.id.row_label);
            holder.votesText= (TextView) convertView.findViewById(R.id.row_subtext);

            //set the holder class
            convertView.setTag(holder);
        }

        else{
            //get all the views once done
            holder = (ViewHolder) convertView.getTag();
        }

        //set all the values in the list
        holder.movieText.setText(currMovie.getName());
        String votesStr = currMovie.getVotes()+" votes";
        holder.votesText.setText(votesStr);
        Bitmap movieIcon = getMovieIcon(currMovie.getName(), currMovie.getRating());
        holder.icon.setImageBitmap(movieIcon);

        return convertView;
    }
}

    /** Creates a unique movie icon based on name and rating */
private Bitmap getMovieIcon(String movieName, String movieRating)
{
    int bgColor = getColor(movieName);
    Bitmap b = Bitmap.createBitmap(48, 48, Bitmap.Config.ARGB_8888);
    b.eraseColor(bgColor); // fill bitmap with the color
    Canvas c = new Canvas(b);
    Paint p = new Paint();
    p.setAntiAlias(true);
    p.setColor(getTextColor(bgColor));
    p.setTextSize(24.0f);
    c.drawText(movieRating, 8, 32, p);
    return b;
}

/** Construct a color from a movie name */
private int getColor(String name)
{
    String hex = toHexString(name);
    String red = "#"+hex.substring(0,2);
    String green = "#"+hex.substring(2,4);
    String blue = "#"+hex.substring(4,6);
    String alpha = "#"+hex.substring(6,8);
    int color = Color.argb(Integer.decode(alpha), Integer.decode(red), 
                            Integer.decode(green), Integer.decode(blue));
    return color;
}

/** Given a movie name -- generate a hex value from its hashcode */
private String toHexString(String name)
{
    int hc = name.hashCode();
    String hex = Integer.toHexString(hc);
    if (hex.length() < 8)
    {
        hex = hex+hex+hex;
        hex = hex.substring(0,8); // use default color value
    }
    return hex;
}

/** Crude optimization to obtain a contrasting color -- does not work well yet */
private int getTextColor(int bg)
{

    int r = Color.red(bg);
    int g = Color.green(bg);
    int b = Color.blue(bg);
    String hex = Integer.toHexString(r)+Integer.toHexString(g);
    hex += Integer.toHexString(b);

    int cDec = Integer.decode("#"+hex);
    if (cDec > 0xFFFFFF/2)  // go dark for lighter shades
        return Color.rgb(0, 0, 0);
    else
    {
        r = (r+128)%256;
        g = (g+128)%256;
        b = (b+128)%256;
        return Color.rgb(r,g,b);
    }
}


}

我的布局：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ListView
    android:id="@android:id/list" 
    android:layout_height="fill_parent"  
    android:layout_width="match_parent" />
</LinearLayout>

ListRow布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageView android:id="@+id/row_icon" android:padding="2dip"
    android:cacheColorHint="#00000000"
    android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:src="@drawable/icon" />
<LinearLayout android:id="@+id/linearLayout1"
            android:orientation="vertical" 
            android:layout_height="match_parent" 
            android:layout_width="wrap_content">
    <TextView android:id="@+id/row_label" 
 android:layout_width="wrap_content"
        android:layout_height="match_parent" 
        android:text="Terminator 2"
        android:textSize="22sp" />
    <TextView android:id="@+id/row_subtext" 
  android:layout_width="wrap_content"
        android:layout_height="match_parent" 
        android:text="Rating: 5.5, 2340 votes"
        android:textSize="14sp" />          
</LinearLayout>

</LinearLayout>

这就是它的样子：

AsyncTask打破了自定义列表视图

0 个答案: