getView位置不準確

Question

我想顯示數據庫中的信息到我的列表視圖。我可以顯示它，但是當我想要使用它時，我在getView方法中獲得了不準確的位置。你們可以給我一些我應該怎麼做的提示嗎？

public class ViewAdapter extends BaseAdapter { 
    LayoutInflater minflater; 


    @Override 
    public int getCount() { 
     return productsList.size(); 
    } 

    @Override 
    public Object getItem(int position) { 
     return null; 
    } 

    @Override 
    public long getItemId(int position) { 
     return position; 
    } 

    public ViewAdapter() { 
     minflater = LayoutInflater.from(getBaseContext()); 

    } 

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

     if (convertView == null) { 
      convertView = minflater.inflate(R.layout.you, null); 

     } 

     final TextView text11 = (TextView) convertView.findViewById(R.id.text11); 
     text11.setText(productsList.get(position).get_productname()); 
     final TextView text22 = (TextView) convertView.findViewById(R.id.text22); 
     text22.setText(productsList.get(position).get_versionname()); 
     final TextView text33 = (TextView) convertView.findViewById(R.id.text33); 
     text33.setText(productsList.get(position).get_date()); 
     final Button update = (Button) convertView.findViewById(R.id.update); 

     update.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

      //  int a = dbhandler.checkDatabase(productsList.get(position).get_date()); 

       final Calendar cal = Calendar.getInstance(); 
       int day = cal.get(Calendar.DAY_OF_MONTH); 
       int month = cal.get(Calendar.MONTH); 
       int year = cal.get(Calendar.YEAR); 
       StringBuffer buffer = new StringBuffer(); 
       buffer.append(day + "-" + (month + 1) + "-" + year); 
       String date = DateFormat.getTimeInstance().format(new Date()); 
       String b = "Date: " + buffer + "\n" + "Time: " + "" + date + "\n"; 
       dbhandler = new mydbhandler(getBaseContext(), null,null,1); 
       dbhandler.updateProduct(position,b); 


       productsList = dbhandler.getFavList(); 
       listview.setAdapter(new ViewAdapter()); 


      } 


     }); 


     return convertView; 
    } 
} 

Answer 1

改變了你可以試試這個代碼，它很適合我

import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.Button; 
import android.widget.ImageView; 
import android.widget.TextView; 


public class ViewAdapter extends BaseAdapter 
{ 
    LayoutInflater minflater; 


    @Override 
    public int getCount() { 
     return productsList.size(); 
    } 
    @Override 
    public Object getItem(int position) { 
     return position; 
    } 


    @Override 
    public long getItemId(int position) { 
     return position; 
    } 

    public ViewAdapter() { 
     minflater = LayoutInflater.from(getBaseContext()); 

    } 

    public class Holder 
    { 
     TextView text11 , text22 ,text33; 
     Button update; 
    } 

@Override 
public View getView(final int position, View convertView, ViewGroup parent) 
{ 
    final Holder holder; 
    if (convertView == null) 
    { 
     convertView = minflater.inflate(R.layout.you, null); 
     holder=new Holder(); 
    holder.text11 = (TextView) convertView.findViewById(R.id.text11); 
    holder.text22 = (TextView) convertView.findViewById(R.id.text22); 
    holder.text33 = (TextView) convertView.findViewById(R.id.text33); 
    holder.update = (Button) convertView.findViewById(R.id.update); 


     convertView.setTag(holder); 
    } 
    else 
    { 
     holder = (Holder) convertView.getTag(); 
    } 
    holder.text11.setText(productsList.get(position).get_productname()); 
    holder.text22.setText(productsList.get(position).get_versionname()); 
    holder.text33.setText(productsList.get(position).get_date()); 

    return convertView; 
} 


} 

Answer 2

在BaseAdapter有一些方法需要被重寫。其中有getCount()。

在創建和諸如此類的東西ListView控件，它調用getCount()。如果這返回一個不等於0的值（我返回了之前在構造函數中初始化的ArrayList的大小），那麼它會調用getView()足夠多次來填充屏幕上的項目。例如，我用20個項目初始化ArrayList。因爲只有8個項目開始適應屏幕上，getView()被稱爲8次，每次要求它要求我回（更精確的位置也想知道行會是什麼樣子在名單上的具體位置，是什麼它需要包含的數據）。如果我向下滾動列表，getView（）會被一遍又一遍地調用，直到我打到列表的末尾，在我的例子中是20個項目/行。

notifyDataSetChanged()所做的是...當被調用時，它會查看屏幕上顯示的內容（更確切地說是哪些行索引），並調用getView()與這些位置。

也就是說，如果你在列表中顯示第8項（所以這些是那些在屏幕上可見），你在列表中添加了第二和第三項之間的另一個項目，你叫notifyDataSetChanged()然後getView()被稱爲8次，位置從0開始到7結束，並且因爲在getView（）方法中你從ArrayList獲取數據，它會自動返回列表中插入的新項目以及前8（7而不是8，因爲最後一個項目向下一個位置，所以它不再可見），ListView將重繪或任何與這些項目。 從複製here

您可以嘗試編輯的代碼。

public class ViewAdapter extends BaseAdapter { 
    LayoutInflater minflater; 


    @Override 
    public int getCount() { 
     return productsList.size(); 
    } 

    @Override 
    public Object getItem(int position) { 
     return productsList.get(position); 
    } 

    @Override 
    public long getItemId(int position) { 
     return position; 
    } 

    public ViewAdapter() { 
     minflater = LayoutInflater.from(getBaseContext()); 

    } 

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

     if (convertView == null) { 
      convertView = minflater.inflate(R.layout.you, null); 

     } 

     final TextView text11 = (TextView) convertView.findViewById(R.id.text11); 
     text11.setText(productsList.get(position).get_productname()); 
     final TextView text22 = (TextView) convertView.findViewById(R.id.text22); 
     text22.setText(productsList.get(position).get_versionname()); 
     final TextView text33 = (TextView) convertView.findViewById(R.id.text33); 
     text33.setText(productsList.get(position).get_date()); 
     final Button update = (Button) convertView.findViewById(R.id.update); 

     update.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

      //  int a = dbhandler.checkDatabase(productsList.get(position).get_date()); 

       final Calendar cal = Calendar.getInstance(); 
       int day = cal.get(Calendar.DAY_OF_MONTH); 
       int month = cal.get(Calendar.MONTH); 
       int year = cal.get(Calendar.YEAR); 
       StringBuffer buffer = new StringBuffer(); 
       buffer.append(day + "-" + (month + 1) + "-" + year); 
       String date = DateFormat.getTimeInstance().format(new Date()); 
       String b = "Date: " + buffer + "\n" + "Time: " + "" + date + "\n"; 
       dbhandler = new mydbhandler(getBaseContext(), null,null,1); 
       dbhandler.updateProduct(position,b); 

       productsList.clear(); 
       productsList.addAll(dbhandler.getFavList()); 
       ((ViewAdapter)listview.getAdapter()).notifyDataSetChanged(); 


      } 


     }); 


     return convertView; 
    } 
}