我有一个自定义列表视图适配器类，listview正在对话框中加载。我想要做的是单击一个按钮并删除该行，但是我nullpointerexception在customlistview适配器上得到了一个，这是customlistview适配器类的代码：
@SuppressWarnings("rawtypes")
public class CustomListViewVoidAdapter extends ArrayAdapter{
String url_delete= "http://192.168.1.70:80/delete_from_orders.php";
String food_name, food_add, food_remove,tab_num;
LayoutInflater inflater;
Context context;
List<ListViewItemVoid> items;
private static final String TAG_SUCCESS = "success";
ListViewItemVoid holder = null;
CustomListViewVoidAdapter adapter;
ListViewItemVoid item;
ListViewItemVoid item_selected;
ListView lv;
JSONParser jsonParser = new JSONParser();
public CustomListViewVoidAdapter(Context context, int textViewResourceId, List<ListViewItemVoid> items) {
super(context, textViewResourceId);
Log.i("","const");
this.items = items;
this.context = context;
inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
Log.i("CLVOA","Constructor");
}
@Override
public int getCount() {
Log.i("CLVOA","getCount()");
return items.size();
}
@Override
public ListViewItemVoid getItem(int position) {
Log.i("Item","getItem");
return ((CustomListViewVoidAdapter) items).getItem(position);
}
@Override
public long getItemId(int position) {
Log.i("CLVOA","getItemId");
return ((CustomListViewVoidAdapter) items).getItemId(position);
}
@Override
public View getView(final int position, final View convertView, ViewGroup parent) {
item = items.get(position);
View vi = convertView;
Log.i("akhada","adapter"+adapter);
if(vi==null)
{
item_selected= items.get(position);
vi= inflater.inflate(R.layout.void_food, null);
holder = new ListViewItemVoid();
holder.table_number=(TextView)vi.findViewById(R.id.tablenumber);
holder.food_ordered=(TextView)vi.findViewById(R.id.ordered);
holder.food_added=(TextView)vi.findViewById(R.id.foodadded);
holder.food_removed=(TextView)vi.findViewById(R.id.foodremoved);
holder.void_button=(Button)vi.findViewById(R.id.voidbutton);
lv= (ListView) vi.findViewById(R.id.Mytemp);
holder.void_button.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
adapter = new CustomListViewVoidAdapter(context,R.layout.mytemp, items);
if (adapter!=null)
{
Log.i("","ata3 hon");
item_selected= items.get(position);
items.remove(item_selected);
Log.i("wosil ", " hon");
lv.setAdapter(adapter);
new DeleteOrder().execute();
}
Log.i("","selected item position"+item_selected);
}});
vi.setTag(holder);
}
else{
holder = (ListViewItemVoid) vi.getTag();
}
holder.food_ordered.setText(""+item.food_name);
holder.food_added.setText(""+item.add);
holder.food_removed.setText(""+item.remove);
holder.table_number.setText(""+item.table_num);
food_name= holder.food_ordered.getText().toString();
food_add= holder.food_added.getText().toString();
food_remove= holder.food_removed.getText().toString();
tab_num= holder.table_number.getText().toString();
Log.i ("food name deleting ", " deleting food name: " + food_name);
return vi;
}
class DeleteOrder extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
}
/**
* Deleting product
* */
@Override
protected String doInBackground(String... args) {
// Check for success tag
int success;
try {
// Building Parameters
//String food_name, food_add, food_remove,tab_num;
Log.i ("woslit l","wosil l food "+food_name);
Log.i ("woslit l","wosil l add "+food_add);
Log.i ("woslit l","wosil l remove "+food_remove);
Log.i ("woslit l","wosil l table number "+tab_num);
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("table_id", tab_num));
params.add(new BasicNameValuePair("add", food_add));
params.add(new BasicNameValuePair("remove", food_remove));
params.add(new BasicNameValuePair("food", food_name));
Log.i("","honee");
// getting product details by making HTTP request
JSONObject json = jsonParser.makeHttpRequest(
url_delete, "POST", params);
// check your log for json response
Log.d("Delete Product", json.toString());
// json success tag
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
Log.i("del", "deleted");
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
//}
}}
在我的主要活动中：
static class ListViewItemVoid{
public TextView table_number;
public TextView food_added;
public TextView food_removed;
public TextView food_ordered;
public String food_name;
public String add;
public String remove;
public String table_num;
public Button void_button;
}
mytemp 是 listview xml 文件， items 是列表：
List<ListViewItemVoid> items;
我知道上下文有问题，但我不知道该怎么办......
我想将主要活动的上下文传递到 customlistview 活动类中。
来自 logcat 的错误：
08-31 13:16:45.140: E/AndroidRuntime(1736): FATAL EXCEPTION: main
08-31 13:16:45.140: E/AndroidRuntime(1736): java.lang.NullPointerException
08-31 13:16:45.140: E/AndroidRuntime(1736): at
com.primeco.IOrderRes.CustomListViewVoidAdapter$1.onClick(CustomListViewVoidAdapter.java:94 )
08-31 13:16:45.140: E/AndroidRuntime(1736): at
android.view.View.performClick(View.java:4202)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
android.view.View$PerformClick.run(View.java:17340)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
android.os.Handler.handleCallback(Handler.java:725)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
android.os.Handler.dispatchMessage(Handler.java:92)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
android.os.Looper.loop(Looper.java:137)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
android.app.ActivityThread.main(ActivityThread.java:5039)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
java.lang.reflect.Method.invokeNative(Native Method)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
java.lang.reflect.Method.invoke(Method.java:511)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
08-31 13:16:45.140: E/AndroidRuntime(1736): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
08-31 13:16:45.140: E/AndroidRuntime(1736):
at dalvik.system.NativeStart.main(Native Method)