キャッシュの概念を理解しようとしています。上下listviewにスクロールすると遅れます。これに関するAndroidチュートリアルを理解しようとしました。しかし、それはあまり役に立ちませんでした。
私を助けてくれた人々から言われたように、ビューをviewHolderに変更しました。
しかし、今、私は新しいエラーに遭遇しています。
戻り型は互換性がありません
ArrayAdapter<Movie>.getView(int, View, ViewGroup)
public class MovieRatingsActivity extends ListActivity
{
private ArrayList<Movie> movies = new ArrayList<Movie>();
private LayoutInflater mInflater;
private LruCache<String, Bitmap> cache;
/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
initializeUI();
}
private void initializeUI()
{
mInflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
InputStream inputStream = getResources().openRawResource( R.raw.ratings);
movies = Movie.loadFromFile(inputStream);
setListAdapter(new RowIconAdapter(this, R.layout.listrow, R.id.row_label, movies));
}
/** 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)
{
View row = mInflater.inflate(R.layout.listrow, parent, false);
Movie currMovie = movies.get(pos);
if (currMovie != null)
{
ImageView icon = (ImageView) row.findViewById(R.id.row_icon);
TextView movieText = (TextView) row.findViewById(R.id.row_label);
TextView votesText = (TextView) row.findViewById(R.id.row_subtext);
movieText.setText(currMovie.getName());
String votesStr = currMovie.getVotes()+" votes";
votesText.setText(votesStr);
Bitmap movieIcon = getMovieIcon(currMovie.getName(), currMovie.getRating());
icon.setImageBitmap(movieIcon);
Log.w("MVMVMVMVMVMV", "Creating row view at position "+pos+" movie "+currMovie.getName());
}
return row;
}
}
*/
/*NEW CODE WHERE ERROR IS THROWN*/
public ViewHolder getView(int pos, View convertView, ViewGroup parent)
{
ViewHolder holder = new ViewHolder();
Movie currMovie = movies.get(pos);
if (currMovie != null)
{
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);
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);
Log.w("MVMVMVMVMVMV", "Creating row view at position "+pos+" movie "+currMovie.getName());
}
return holder;
}
}
/** 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);
}
}