android:為具有不同專案佈局的ListView建立ViewHolders

ListView具有內建的型別管理系統.在適配器中，您有几種型別的專案，每種都有各自的视圖和佈局.通過重寫getItemViewType以返迴给定位置的資料型別，可以使ListView傳遞该型別資料的正確的convertview.然後，在您的getView方法中只需檢查資料型別並使用switch語句以不同方式處理每種型別。

每个Layout型別都應该有自己的viewholder，以便命名清楚和易於維護.為ViewHolders命名与每種資料型別相關的名稱，以使所有內容保持一致。

尝試將所有內容重叠到一个ViewHolder中是不值得的。

編輯 例子

@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
    int viewType = this.getItemViewType(position);
    switch(viewType)
    {
       case TYPE1:
        Type1Holder holder1; 
         View v = convertView; 
         if (v == null) { 
             LayoutInflater vi = (LayoutInflater)getContext().getSystemService     (Context.LAYOUT_INFLATER_SERVICE); 
             v = vi.inflate(R.layout.layout_mylistlist_item_type_1, parent, false); 
             holder1 = new Type1Holder (); 
             holder1.text = (TextView) v.findViewById(R.id.mylist_itemname); 
             v.setTag(holder1); 
         } 
         else { 
             holder1 = (Type1Holder)v.getTag(); 
         } 
         MyListItem myItem = m_items.get(position); 
         // set up the list item 
         if (myItem != null) { 
             // set item text 
             if (holder1.text != null) { 
                 holder1.text.setText(myItem.getItemName()); 
             } 
         } 
         // return the created view 
         return v; 

     case TYPE2:
            Type2Holder holder2; 
         View v = convertView; 
         if (v == null) { 
             LayoutInflater vi = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
             v = vi.inflate(R.layout.layout_mylistlist_item_type_2, parent, false); 
             holder2 = new Type2Holder (); 
             holder2.text = (TextView) v.findViewById(R.id.mylist_itemname); 
             holder2.icon = (ImageView) v.findViewById(R.id.mylist_itemicon); 
             v.setTag(holder1); 
         } 
         else { 
             holder2 = (Type2Holder)v.getTag(); 
         } 
         MyListItem myItem = m_items.get(position); 
         // set up the list item 
         if (myItem != null) { 
             // set item text 
             if (holder2.text != null) { 
                 holder2.text.setText(myItem.getItemName()); 
             } 
             if(holder2.icon != null)
                 holder2.icon.setDrawable(R.drawable.icon1);
         } 

         // return the created view 
         return v; 

       default:
           //Throw exception, unknown data type
    }
}

另一个例子。

公共類CardArrayAdapter擴充套件了ArrayAdapter {

public CardArrayAdapter(Context context) {
    super(context, R.layout.adapter_card);
}
@Override
public View getView(int position, View view, ViewGroup parent) {
    final Card card = getItem(position);
    ViewHolder holder;
    //if (view != null) {
        //holder = (ViewHolder) view.getTag();
    //} else {
    Log.d("card.important?", card.name + " = " + Boolean.toString(card.important));
    if(card.important) {
        view = LayoutInflater.from(getContext()).inflate(R.layout.adapter_card_important, parent, false);
    }else {
        view = LayoutInflater.from(getContext()).inflate(R.layout.adapter_card, parent, false);
    }
    holder = new ViewHolder(view);
    view.setTag(holder);
    //}
    // IMG
    Picasso.with(getContext())
            .load(card.logo)
            .placeholder(R.drawable.ic_phonebook)
            .error(R.drawable.ic_phonebook)
            .fit()
            .centerCrop()
            .transform(new CircleTransform())
            .into(holder.logo);
    holder.name.setText(card.name);
    if(card.important) {
        holder.category.setVisibility(View.VISIBLE);
        if (card.category.equals("airline")) {
            card.category = "airlines";
        }
        int id = getContext().getResources().getIdentifier(card.category, "string", getContext().getPackageName());
        holder.category.setText(getContext().getResources().getString(id));
    }else {
        holder.category.setVisibility(View.GONE);
    }
    holder.tagline.setText(card.tagline);
    holder.favorite.setChecked(card.favorite);
    holder.favorite.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            card.favorite = ((CheckBox) v).isChecked();
            card.save();
        }
    });
    return view;
}
static class ViewHolder {
    @InjectView(R.id.logo) ImageView logo;
    @InjectView(R.id.name) TextView name;
    @InjectView(R.id.category) TextView category;
    @InjectView(R.id.tagline) TextView tagline;
    @InjectView(R.id.favorite) CheckBox favorite;
    public ViewHolder(View view) {
        ButterKnife.inject(this, view);
    }
}

}