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POHow to get rid of lag/jitter in listview? Can anybody help me with my code on how to cache it?
 

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  1. POHow to get rid of lag/jitter in listview? Can anybody help me with my code on how to cache it?
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    <p>I am trying to understand the concept of cache. Can anybody help me with my code, as i my listview is having a lag whenever i scroll up or down. I tried understanding the android tutorial on this. But it didnt help me much. </p> <p>As Told by my people who helped me i changed my view to viewHolder.</p> <p>But now i am coming accross a new error. The return type is incompatible with ArrayAdapter.getView(int, View, ViewGroup)</p> <p>public class MovieRatingsActivity extends ListActivity</p> <p>{</p> <pre><code>private ArrayList&lt;Movie&gt; movies = new ArrayList&lt;Movie&gt;(); private LayoutInflater mInflater; private LruCache&lt;String, Bitmap&gt; 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&lt;Movie&gt; { private ArrayList&lt;Movie&gt; movies; public RowIconAdapter(Context c, int rowResourceId, int textViewResourceId, ArrayList&lt;Movie&gt; 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; } } </code></pre> <p>*/ /<em>NEW CODE WHERE ERROR IS THROWN</em>/</p> <p>public ViewHolder getView(int pos, View convertView, ViewGroup parent)</p> <p>{</p> <pre><code> 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() &lt; 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 &gt; 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); } } </code></pre> <p>}</p>
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    1. COtry adding android:scrollingCache="true" to your listview in xml file
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      1. POHow to get rid of lag/jitter in listview? Can anybody help me with my code on how to cache it?
      1. USAthul Harikumar
    2. COMy app continues to crash. even if i add scrollingcache="true" It only happens when i start scrolling fast.
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      1. POHow to get rid of lag/jitter in listview? Can anybody help me with my code on how to cache it?
      1. USuser2380358
    3. COenable fast scrolling too in xml properties of list view
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      1. POHow to get rid of lag/jitter in listview? Can anybody help me with my code on how to cache it?
      1. USAthul Harikumar
 

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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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