How to keep listview item loaded

Question

How to keep listview item loaded

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#1 by (1 votes)

1

I have this listview

main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
tools:context="${relativePackage}.${activityClass}"
xmlns:ads = "http://schemas.android.com/apk/res-auto"
android:background="#ffffff"
>

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="0dp"
    android:layout_above="@+id/ad">

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

<com.google.android.gms.ads.AdView
    android:id="@+id/ad"
    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">
</com.google.android.gms.ads.AdView>

layoutlist.xml

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

<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:text="Bertioga"
    android:textSize="25dp"
    android:textColor="#000000"
    android:gravity="center"
    android:background="@drawable/backrepeat"
    android:id="@+id/nomePraia"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true" />

<ImageView
    android:layout_marginTop="10dp"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:id="@+id/fotoPraia"
    android:layout_below="@+id/nomePraia"
    android:layout_centerHorizontal="true"
    android:layout_above="@+id/bt" />

<TextView
    android:layout_marginLeft="5dp"
    android:layout_marginRight="5dp"
    android:layout_marginTop="10dp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceSmall"
    android:text="Coemçar a descrição ...."
    android:id="@+id/descricao"
    android:maxLength="400"
    android:textColor="#000000"
    android:layout_alignTop="@+id/btFavorito"
    android:layout_toEndOf="@+id/btFavorito"
    android:gravity="left"
    android:layout_toStartOf="@+id/bt"
    android:layout_toRightOf="@+id/btFavorito"
    android:layout_toLeftOf="@+id/bt" />

<RelativeLayout
    android:layout_marginTop="10dp"
    android:layout_marginLeft="5dp"
    android:layout_marginRight="3dp"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        style="?android:attr/buttonStyleSmall"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/btVerMais"
        android:id="@+id/btVerMais"
        android:background="#fff"
        android:textColor="@color/wallet_link_text_light"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <ImageButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btFavorito"

        android:background="@drawable/ic_action_favorite"
        android:layout_alignTop="@+id/bt"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/bt"
        android:background="@drawable/ic_popup_menu"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />
</RelativeLayout>

adapter.java

    public View getView(final int position, View v, ViewGroup parent) {
    view = mInflater.inflate(R.layout.layoutlist, null);
    final ListenerItem categoria = itens.get(position);
    ImageView foto = (ImageView) view.findViewById(R.id.fotoPraia);
    int drawableId = context.getResources().getIdentifier(categoria.nome_foto, "drawable", packageName);
    LoadBitmapImage bitmapTask = new LoadBitmapImage(foto,width,context);
    bitmapTask.execute(drawableId);
    TextView nomePraia = (TextView) view.findViewById(R.id.nomePraia);

    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;


    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;
}

In this my ListView loads an item ai when it goes down ScrollView of ListView is loading the other items one at a time I wanted to keep these items loaded, after loading once do not need to load again

New Adapter

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

    View view;
    final ViewHolder holder;
    if(convertView == null) {
        view = mInflater.inflate(R.layout.layoutlist, parent, false);
        holder = new ViewHolder();


        holder.foto = (ImageView) view.findViewById(R.id.fotoPraia);
        holder.btFavorito = (ImageButton) view.findViewById(R.id.btFavorito);
        holder.nomePraia = (TextView) view.findViewById(R.id.nomePraia);
        holder.descricao = (TextView) view.findViewById(R.id.descricao);
        holder.bt = (ImageButton) view.findViewById(R.id.bt);
        holder.btVerMais = (Button) view.findViewById(R.id.btVerMais);
        view.setTag(holder);
    }else {
        view = convertView;
        holder = (ViewHolder)view.getTag();
    }

    final ListenerItem categoria = itens.get(position);
    int drawableId = context.getResources().getIdentifier(categoria.nome_foto, "drawable", packageName);

    LoadBitmapImage bitmapTask = new LoadBitmapImage(holder.foto,width,context);
    bitmapTask.execute(drawableId);

    String desc="";
    if(categoria.descricao.length()<397){
        holder.btVerMais.setVisibility(View.INVISIBLE);
        desc=categoria.descricao;
    }else{
        for(int i=0;i<397;i++){
            desc=desc+categoria.descricao.charAt(i);
        }
        desc=desc+"...";
    }
    holder.nomePraia.setText(categoria.nome);
    holder.descricao.setText(desc);

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

            listenerItem = itens.get(position);
            open(listenerItem);
        }
    });
    holder.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;
                holder.btFavorito.setImageResource(R.drawable.ic_action_favorite);

            } else {
                listenerItem.favorito = true;
                holder.btFavorito.setImageResource(R.drawable.ic_action_favorite_v);

            }

            try {
                daoItem.createOrUpdate(listenerItem);

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

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

        }
    });

    return view;
}

ViewHolder class

private class ViewHolder {
public ImageView foto;
public TextView nomePraia;
public ImageButton btFavorito;
public TextView descricao;
public ImageButton bt;
public Button btVerMais;

}

Mode I load the images Class I'm using to load LoadBitmapImage

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

public LoadBitmapImage(ImageView imageView,int width,Context context) {
    this.width = width;
    this.context = context;
    // 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[0]);
    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);
        }
    }
}

}

android listview

asked by anonymous 08.04.2015 / 02:45

1 answer

Remove part without fixed size from an xml Editing exif from an image

score 1 · Accepted Answer

There is a better way to implement the getView method, using the ViewHolders concept, where your Views are in another class (Holder). For example:

@Override
public View getView(int position, View convertView, ViewGroup viewGroup) {
    View v = convertView;
    ViewHolder holder;

    if (convertView == null) {
        holder = new ViewHolder();
        v = ((Activity) mContext).getLayoutInflater().inflate(R.layout.layout, null);
        holder.imageView1 = v.findViewById(R.id.seuImageView);
        holder.textView1 = v.findViewById(R.id.seuTextView);

        v.setTag(holder);
    } else {
        holder = (ViewHolder) v.getTag();
    }

    Object item = getItem(position);

    return v;
}

private class ViewHolder {
    ImageView imageView1;
    TextView textView1;
}

The ListView recycles the list items so that they do not get created again, basically it keeps in memory only the ones on the screen and the next item to be displayed. Doing your getView like this, using a holder to manipulate your Views, prevents ListView from reusing your Views already created by modifying your data.