我正在开发一个应用程序，但在自定义适配器中出现空指针异常。我的自定义适配器代码如下 -
public class CustomCursorAdapter extends CursorAdapter {
SQLiteDatabase dh = DatabaseHelpereKOT.getInstance().getDb();
private LayoutInflater mInflater;
private Context mContext;
Cursor cursor, c;
boolean isMain;
View convertView;
ViewHolder holder;
private String item;
private String description;
private String name_NO;
private String description_NO;
private int category;
private double price;
private LayoutInflater inflater;
private View detailsLayout;
private AlertDialog detailsDialog;
private final String TAG = "RestaurantHome";
private Integer id;
MainScreen main_screen_obj;
public Handler addMenuItemHandler = new Handler() {
@Override
public void handleMessage(android.os.Message msg) {
if (msg.what == 1) {
System.out.println("inside handler");
Toast.makeText(mContext, (String) msg.obj, Toast.LENGTH_SHORT)
.show();
}
};
};
public CustomCursorAdapter(Context context, Cursor c, Boolean isMain) {
super(context, c);
mInflater = LayoutInflater.from(context);
mContext = context;
cursor = c;
this.isMain = isMain;
// restaurantHome = (RestaurantHome) context;
}
public CustomCursorAdapter(Context context, Cursor c) {
super(context, c);
mInflater = LayoutInflater.from(context);
mContext = context;
cursor = c;
}
@Override
public void bindView(View view, Context context, final Cursor cursor) {
holder = (ViewHolder) view.getTag();
holder.setTvTitle((TextView) view
.findViewById(R.id.main_body_item_title));
holder.setTvPrice((TextView) view
.findViewById(R.id.main_body_item_title_price));
holder.getTvPrice().setText(
cursor.getString(cursor.getColumnIndex("Item_cost")) + ".00");
holder.getTvTitle().setText(
cursor.getString(cursor.getColumnIndex("name_NO")));
holder.getTvDescription().setText(
cursor.getString(cursor.getColumnIndex("description_NO")));
int _id = cursor.getInt(cursor.getColumnIndex("_id"));
view.setTag(R.id.main_body_item_title, _id);
// System.out.println("_id :"+_id);
int type = cursor.getInt(cursor.getColumnIndex("item_type"));
if (type == 1) {
//holder.getImType().setPadding(6, 0, 0, 0);
holder.getImType().setBackgroundResource(R.drawable.non_veg);
} else {
holder.getImType().setBackgroundResource(R.drawable.veg);
}
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
final ViewHolder holder;
// System.out.println("parent.getTag(R.id.main_body_item_title) :"+parent.getTag(R.id.main_body_item_title));
c = cursor;
convertView = mInflater.inflate(R.layout.list_row, parent, false);
holder = new ViewHolder();
holder.setId(cursor.getInt(0));
((ImageView) (convertView
.findViewById(R.id.main_body_item_title_second_pics)))
.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
// System.out.println(view.getTag());
addToDB(holder.getId());
//Toast.makeText(getApplicationContext(), "insertDataOrder method", 2000).show();
System.out.println("i m in ryt [palce");
}
});
convertView.setTag(holder);
return convertView;
}
void addToDB(Integer objId) {
if (objId != null) {
int _id = objId;
Cursor cursor = dh.query(DatabaseHelpereKOT.RESTAURANT_menu_temp,
new String[] { "_id", "name", "description", "name_NO",
"description_NO", "availablequantity", "itemprice",
"imagename", "smallImageName", "item_type",
"category" }, "_id=?", new String[] { String
.valueOf(_id) }, null, null, null);
if ((cursor != null) && (cursor.getCount() > 0)
&& cursor.moveToFirst()) {
item = cursor.getString(cursor.getColumnIndex("name"));
description = cursor.getString(cursor
.getColumnIndex("description"));
name_NO = cursor.getString(cursor.getColumnIndex("name_NO"));
description_NO = cursor.getString(cursor
.getColumnIndex("description_NO"));
category = cursor.getInt(cursor.getColumnIndex("category"));
price = cursor.getDouble(cursor.getColumnIndex("itemprice"));
// _id INTEGER PRIMARY KEY,type INTEGER,title TEXT,description
//
// TEXT, price DOUBLE,category INTEGER
ContentValues orderValues = new ContentValues();
Log.d(TAG, "Values Insert Order : " + category + ", " + item
+ ", " + description + ", " + price);
orderValues.put("category", category);
orderValues.put("title", name_NO);
orderValues.put("description", description);
orderValues.put("price", price);
/*if (RestaurantHome.Applocale.equals("no")) {
orderValues.put("title", name_NO);
orderValues.put("description", description_NO);
}*/
dh.insert(DatabaseHelpereKOT.RESTAURANT_menu_order, null, orderValues);
String msg = "Menu Item Added Successfully";
Message msgObject = new Message();
msgObject.what = 1;
msgObject.obj = msg;
addMenuItemHandler.sendMessage(msgObject);
System.out.println("Click my Order");
/*System.out.println("OrderListAdapter.totalCount ="
+ OrderListAdapter.totalCount);*/
// select COUNT(*) from CDs;
/*
* restaurantHome.intiliazeOrderListDialog();
* restaurantHome.createOrderListDialog();
* restaurantHome.showOrderListDialog();
*/
}
cursor.close();
}
}
}
这是我的股份跟踪。
09-25 10:08:01.192: E/AndroidRuntime(11097): FATAL EXCEPTION: main
09-25 10:08:01.192: E/AndroidRuntime(11097): java.lang.NullPointerException
09-25 10:08:01.192: E/AndroidRuntime(11097): at com.dm.ekot.MainScreen$1.onClick(MainScreen.java:149)
09-25 10:08:01.192: E/AndroidRuntime(11097): at android.view.View.performClick(View.java:3110)
09-25 10:08:01.192: E/AndroidRuntime(11097): at android.view.View$PerformClick.run(View.java:11928)
09-25 10:08:01.192: E/AndroidRuntime(11097): at android.os.Handler.handleCallback(Handler.java:587)
09-25 10:08:01.192: E/AndroidRuntime(11097): at android.os.Handler.dispatchMessage(Handler.java:92)
09-25 10:08:01.192: E/AndroidRuntime(11097): at android.os.Looper.loop(Looper.java:132)
09-25 10:08:01.192: E/AndroidRuntime(11097): at android.app.ActivityThread.main(ActivityThread.java:4025)
09-25 10:08:01.192: E/AndroidRuntime(11097): at java.lang.reflect.Method.invokeNative(Native Method)
我在这段代码中遇到错误-
Cursor starterCursor = null;
startManagingCursor(starterCursor);
starterCursor = dh.query(DatabaseHelpereKOT.RESTAURANT_menu_temp, null,
"item_id=?", new String[] { String.valueOf("1") },
null, null, null);
System.out.println("before defore cahnge cursor"+starterCursor);
adapter.changeCursor(starterCursor);
System.out.println("before menulist setadapter");
menuList.setAdapter(adapter);
在这一行
adapter.changeCursor(starterCursor);
我的数据库的这种结构
"create table "
+ RESTAURANT_menu_temp
+ " (_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,item_id TEXT , item_type TEXT , item_name TEXT , Item_cost DOUBLE)",
，我必须在数据库中保存一些数据，这些数据正在成功进行，通过单击一个按钮，我必须通过自定义适配器显示所有这些数据，但是我得到空指针异常，问题出在哪里，请一些人帮助我。我我真的很感谢所有人。我是安卓新手。