Question

我想从MenuCard Activity中选择各种菜肴这是我的ProductAdapter

import java.util.ArrayList;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.ListView;
import android.widget.TextView;



 import com.beans.Product;
 import com.vinayak.hk.MenuCard;
 import com.vinayak.hk.R;

 public class ProductAdapter extends ArrayAdapter<Product> {

ArrayList<Product> allProducts;
LayoutInflater vi;
int Resource;
ViewHolder holder;


public ProductAdapter (Context context , int resource ,ArrayList<Product> objects)
{
    super(context, resource, objects);
    vi = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    Resource = resource;
    allProducts = objects;

}
@Override
public View getView(int position ,View convertView,ViewGroup parent)
    {
        View v = convertView;
        if(v==null)
        {
        holder = new ViewHolder();
        v = vi.inflate(Resource, null);

        holder.name = (TextView) v.findViewById(R.id.tv1);
        holder.price = (TextView) v.findViewById(R.id.price);
        holder.checkbox = (CheckBox) v.findViewById(R.id.cb1);


        v.setTag(holder);

    }

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

    }

    //holder.imageview.setImageResource(R.drawable.ic_launcher);
    holder.name.setText(allProducts.get(position).getProduct_name());



    int s = allProducts.get(position).getProduct_price();
    //Log.d("********************",Integer.toString(s));
    holder.price.setText(Integer.toString(s));

    //final ListView lv = (ListView) parent;
    //holder.checkbox.setChecked(lv.isItemChecked(position));

    //holder.checkbox.setChecked(false);


    return v;

}

static class ViewHolder {

    public TextView name;
    public TextView price;
    public CheckBox checkbox ;


}






 }

我的ListActivity是：

MenuCard.java

 public class MenuCard extends ListActivity {

ListView list;
Button btn1;
String url="";
private ArrayList <Product>  allProducts = new ArrayList<Product>();
private ProductAdapter adapter;
public static boolean[] arrBoolean = null;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.menu_card);

    btn1 = (Button) findViewById(R.id.btn);
    list = getListView();
    Bundle d = getIntent().getExtras();

    url="http://10.0.2.2:8084/Hotelkart/Product?id="+d.getInt("id");


    try{
        ConnectivityManager c =(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);                  
        NetworkInfo n =c.getActiveNetworkInfo();
        if (n!= null && n.isConnected()){





            Log.d("url*********",url);

            new Background().execute(url);
        }
       }catch(Exception e){}




    //Toast.makeText(getApplicationContext(), url, Toast.LENGTH_LONG).show();

 adapter = new  ProductAdapter(getApplicationContext(),R.layout.productrow,allProducts);

  setListAdapter(adapter);
  list.setItemsCanFocus(false);
  btn1.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
    // TODO Auto-generated method stub

    SparseBooleanArray checked = list.getCheckedItemPositions();;



    ArrayList<String> selectedItems = new ArrayList<String>();
    ArrayList<Integer> selectedItemsPrice = new ArrayList<Integer>();
    ArrayList<Integer> selectedItemsId = new ArrayList<Integer>();
    Log.d("**************",Integer.toString(checked.size()));
    for (int i = 0; i < checked.size(); i++) {
        // Item position in adapter
        int position = checked.keyAt(i);
        // Add sport if it is checked i.e.) == TRUE!
        if (checked.valueAt(i))
            {
            selectedItems.add(adapter.getItem(position).getProduct_name());
                selectedItemsPrice.add(adapter.getItem(position).getProduct_price());
            selectedItemsId.add(adapter.getItem(position).getProduct_id());
            }
    }

    int k = selectedItems.size();
    int[] outputStrArrId = new int[k];
    int[] outputStrArrPrice = new int[k];
    String[] outputStrArrItem = new String[k];



    for (int i = 0; i < k; i++) {
        outputStrArrItem[i] = selectedItems.get(i);
        outputStrArrId[i] = selectedItemsId.get(i);
        outputStrArrPrice[i] = selectedItemsPrice.get(i);
    }

    Intent intent = new Intent(getApplicationContext(), AddOrder.class);

    // Create a bundle object
    Bundle b = new Bundle();
    b.putStringArray("st3", outputStrArrItem);

    b.putIntArray("st1",outputStrArrId );
    b.putIntArray("st2",outputStrArrPrice );
    // Add the bundle to the intent.
    intent.putExtras(b);

    // start the ResultActivity
    startActivity(intent);




}
});


}

但我在

收到错误

  02-01 00:39:08.579: E/AndroidRuntime(1619): java.lang.NullPointerException
  02-01 00:39:08.579: E/AndroidRuntime(1619):   at  com.vinayak.hk.MenuCard$1.onClick(MenuCard.java:95)
  02-01 00:39:08.579: E/AndroidRuntime(1619):   at android.view.View.performClick(View.java:4438)
  02-01 00:39:08.579: E/AndroidRuntime(1619):   at android.view.View$PerformClick.run(View.java:18422)
  02-01 00:39:08.579: E/AndroidRuntime(1619):   at android.os.Handler.handleCallback(Handler.java:733)

我有问题重新检查项目当我按btn1我得到上面的消息在***************

 for (int i = 0; i < checked.size(); i++)

。请帮助我，

Answer 1

获取NullPointerException，因为getCheckedItemPositions()返回null，因为您正在使用ListView的自定义布局和自定义ArrayAdapter来创建ListView行。

从ListView获取所有选中的项目：

选项1。使用android.R.layout.simple_list_item_multiple_choice布局和默认的ArrayAdapter实现：

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
                            android.R.layout.simple_list_item_multiple_choice,
                            <price_list>);

并确保使用choiceMode

在ListView中启用android:choiceMode="multipleChoice"模式

现在使用getCheckedItemPositions()获取列表中的已检查项目集。

选项2。如果应用程序需要自定义布局和适配器，则自定义ProductAdapter以保存和检索已选中的复选框位置。

参见以下示例： Implement custom multi select ListView with custom ArrayAdapter

ListActivity中的Ckeckebale框

1 个答案: