Listview is catching up

Question

I’ve been ListView

layout.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    xmlns:ads = "http://schemas.android.com/apk/res-auto"
    android:background="#ffffff"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MainActivity">

    <ListView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/praias"
        android:layout_centerHorizontal="true"
        android:layout_above="@+id/adView" />

    <com.google.android.gms.ads.AdView
        android:id="@+id/adView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        ads:adSize="SMART_BANNER"
        ads:adUnitId="@string/banner_unit_id"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"/>

</RelativeLayout>

Main.class:

adapter = new AdapterListView(MainActivity.this,this,itens,height,width,daoItem,getPackageName());
praias.setAdapter(adapter);
praias.setClickable(true);

Adapter.class:

public View getView(final int position, View v, ViewGroup parent) {
    view = mInflater.inflate(R.layout.layoutlist, null);
    final ListenerItem categoria = itens.get(position);

    TextView nomePraia = (TextView) view.findViewById(R.id.nomePraia);
    ImageView foto = (ImageView) view.findViewById(R.id.fotoPraia);
    final ImageButton btFavorito = (ImageButton) view.findViewById(R.id.btFavorito);
    TextView descricao = (TextView) view.findViewById(R.id.descricao);
    final Button bt = (Button) view.findViewById(R.id.bt);
    Button btVerMais = (Button) view.findViewById(R.id.btVerMais);
    String desc="";
    if(categoria.descricao.length()<397){
        btVerMais.setVisibility(View.INVISIBLE);
        desc=categoria.descricao;
    }else{
        for(int i=0;i<397;i++){
            desc=desc+categoria.descricao.charAt(i);
        }
        desc=desc+"...";
    }
    nomePraia.setText(categoria.nome);
    String nome_foto = categoria.nome_foto;
    int drawableId = context.getResources().getIdentifier(nome_foto, "drawable", packageName);
    Log.e(R.drawable.itanhaem3+"",drawableId+"");
    Bitmap bm = BitmapFactory.decodeResource(context.getResources(), drawableId);
    bm = bm.createScaledBitmap(bm, width, width, true);
    foto.setImageBitmap(bm);

    descricao.setText(desc);

    if (categoria.favorito) {
        btFavorito.setImageResource(R.drawable.ic_action_favorite_v);
    } else {
        btFavorito.setImageResource(R.drawable.ic_action_favorite);
    }
    btVerMais.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            ListenerItem listenerItem = new ListenerItem();

            listenerItem = itens.get(position);
            open(listenerItem);
        }
    });
    btFavorito.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            ListenerItem listenerItem = new ListenerItem();

            listenerItem = itens.get(position);

            if (listenerItem.favorito) {
                listenerItem.favorito = false;
                btFavorito.setImageResource(R.drawable.ic_action_favorite);
                chamaToast(false);
            } else {
                listenerItem.favorito = true;
                btFavorito.setImageResource(R.drawable.ic_action_favorite_v);
                chamaToast(true);
            }

            try {
                daoItem.createOrUpdate(listenerItem);

            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    });
    activity.registerForContextMenu(bt);

    bt.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            bt.setId(position);
            activity.openContextMenu(bt);

        }
    });

    return view;
}

public void open(ListenerItem listenerItem){
    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);
    alertDialogBuilder.setMessage(Html.fromHtml(listenerItem.descricao));
    alertDialogBuilder.setPositiveButton(R.string.voltar,null);
    AlertDialog alertDialog = alertDialogBuilder.create();
    alertDialog.show();
}

Whenever this going from one item to the other hangs a little , I do not know why it is so slow this ListView

Screenshots:

Answer 1

The problem is that Voce is processing your image within your Thread UI.

To solve this problem, Google itself recommends AsyncTask, that runs everything in the background and outside of your Thread UI.

public class LoadBitmapImage extends AsyncTask<Integer, Void, Bitmap> {
    private final WeakReference<ImageView> imageViewReference;

    public LoadBitmapImage(ImageView imageView) {
        // Use a WeakReference para ter certeza que sua ImageView sera reciclada
        imageViewReference = new WeakReference<ImageView>(imageView);
    }

    // Carregando a imagem em background
    @Override
    protected Bitmap doInBackground(Integer... drawableId) {
        // Aqui voce utiliza seus proprios metodos para carregar e configurar sua Bitmap
        Bitmap bm = BitmapFactory.decodeResource(context.getResources(), drawableId);
        bm = bm.createScaledBitmap(bm, width, width, true);
        return bm;
    }

    // Quando completo, coloque o Bitmap em sua ImageView
    @Override
    protected void onPostExecute(Bitmap bitmap) {
        if (imageViewReference != null && bitmap != null) {
            final ImageView imageView = imageViewReference.get();
            if (imageView != null) {
                imageView.setImageBitmap(bitmap);
            }
        }
    }
}

And to upload your image, simply:

...
ImageView foto = (ImageView) view.findViewById(R.id.fotoPraia);
LoadBitmapImage bitmapTask = new LoadBitmapImage(foto);
bitmapTask.execute(drawableId);             
...

Reference: http://developer.android.com/training/displaying-bitmaps/process-bitmap.html