我正在构建一个简单的应用程序，它存储一些联系人并检索Android手机设备中的联系人。
我创建了自己的数据库和表格，并将值插入手机中的表格。
我的手机没有扎根。所以我无法访问文件，但我看到值存储在表中。并在模拟器上进行了测试。直到这里很好。
通过从表中获取数据来显示列表中的所有联系人。这也没关系。
但问题是当我尝试删除记录时，它显示logcat中的表名为null（不是例外），并且数据不会被删除。但在模拟器中，数据将从表中删除。我无法通过电话实现这一目标。
这是我的删除代码，
public boolean onContextItemSelected(MenuItem item) {
super.onContextItemSelected(item);
AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item
.getMenuInfo();
int menuItemIndex = item.getItemId();
String[] menuItems = getResources().getStringArray(R.array.menu);
String menuItemName = menuItems[menuItemIndex];
String listItemName = Customers[info.position];
if (item.getTitle().toString().equalsIgnoreCase("Delete")) {
Toast.makeText(
context,
"Selected List item is: " + listItemName + "MenuItem is: "
+ menuItemName, Toast.LENGTH_LONG).show();
DB = context.openOrCreateDatabase("CustomerDetails.db",
MODE_PRIVATE, null);
try {
int pos = info.position;
pos = pos + 1;
Log.d("", "customers[pos]: " + Customers[info.position]);
Cursor c = DB
.rawQuery(
"Select customer_id,first_name,last_name from CustomerInfo",
null);
int rowCount = c.getCount();
DB.delete(Table_name,
"customer_id" + "=" + String.valueOf(pos), null);
DB.close();
Log.d("", "" + String.valueOf(pos));
Toast.makeText(context, "Deleted Customer", Toast.LENGTH_LONG)
.show();
// Customers[info.position]=null;
getCustomers();
} catch (Exception e) {
Toast.makeText(context, "Delete unsuccessfull",
Toast.LENGTH_LONG).show();
}
}
这是我的logcat，
07-02 10:12:42.976: D/Cursor(1560): Database path: CustomerDetails.db
07-02 10:12:42.976: D/Cursor(1560): Table name : null
07-02 10:12:42.984: D/Cursor(1560): Database path: CustomerDetails.db
07-02 10:12:42.984: D/Cursor(1560): Table name : null
不知道数据未被删除的原因。数据存在于表中。
请更正我的代码。 任何帮助表示赞赏!!
答案 0 :(得分：1)
您的customer_id类型为整数，而您在下一行中将其作为字符串类型传递，
DB.delete(Table_name,"customer_id" + "=" + String.valueOf(pos), null);
这就是它返回false的原因，尝试将其作为整数使用，如下所示，
DB.delete(Table_name,"customer_id" + "=" + pos, null);
答案 1 :(得分：0)
如果可能，也尝试这种方法。
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
public class RegistrationAdapter {
SQLiteDatabase database_ob;
RegistrationOpenHelper openHelper_ob;
Context context;
public RegistrationAdapter(Context c) {
context = c;
}
public RegistrationAdapter opnToRead() {
openHelper_ob = new RegistrationOpenHelper(context,
openHelper_ob.DATABASE_NAME, null, openHelper_ob.VERSION);
database_ob = openHelper_ob.getReadableDatabase();
return this;
}
public RegistrationAdapter opnToWrite() {
openHelper_ob = new RegistrationOpenHelper(context,
openHelper_ob.DATABASE_NAME, null, openHelper_ob.VERSION);
database_ob = openHelper_ob.getWritableDatabase();
return this;
}
public void Close() {
database_ob.close();
}
public long insertDetails(String fname, String lname) {
ContentValues contentValues = new ContentValues();
contentValues.put(openHelper_ob.FNAME, fname);
contentValues.put(openHelper_ob.LNAME, lname);
opnToWrite();
long val = database_ob.insert(openHelper_ob.TABLE_NAME, null,
contentValues);
Close();
return val;
}
public Cursor queryName() {
String[] cols = { openHelper_ob.KEY_ID, openHelper_ob.FNAME,
openHelper_ob.LNAME };
opnToWrite();
Cursor c = database_ob.query(openHelper_ob.TABLE_NAME, cols, null,
null, null, null, null);
return c;
}
public Cursor queryAll(int nameId) {
String[] cols = { openHelper_ob.KEY_ID, openHelper_ob.FNAME,
openHelper_ob.LNAME };
opnToWrite();
Cursor c = database_ob.query(openHelper_ob.TABLE_NAME, cols,
openHelper_ob.KEY_ID + "=" + nameId, null, null, null, null);
return c;
}
public long updateldetail(int rowId, String fname, String lname) {
ContentValues contentValues = new ContentValues();
contentValues.put(openHelper_ob.FNAME, fname);
contentValues.put(openHelper_ob.LNAME, lname);
opnToWrite();
long val = database_ob.update(openHelper_ob.TABLE_NAME, contentValues,
openHelper_ob.KEY_ID + "=" + rowId, null);
Close();
return val;
}
public int deletOneRecord(int rowId) {
// TODO Auto-generated method stub
opnToWrite();
int val = database_ob.delete(openHelper_ob.TABLE_NAME,
openHelper_ob.KEY_ID + "=" + rowId, null);
Close();
return val;
}
}
openhelper.java
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class RegistrationOpenHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "REGISTRATION_DB";
public static final String TABLE_NAME = "REGISTRATION_TABLE";
public static final String TABLE_NAME_ONE = "REGISTRATION_TABLE_ONE";
public static final int VERSION = 1;
public static final String KEY_ID = "_id";
public static final String FNAME = "F_NAME";
public static final String PKEY_ID = "pid";
public static final String PROFILE = "profile";
public static final String LNAME = "L_NAME";
public static final String SCRIPT = "create table " + TABLE_NAME + " ("
+ KEY_ID + " integer primary key autoincrement, " + FNAME
+ " text not null, " + LNAME + " text not null );";
public static final String PROFILE_TABLE = "create table " + TABLE_NAME_ONE + " ("
+ PKEY_ID + " integer primary key autoincrement, " + PROFILE
+ " text not null, );";
/* public static final String PROFILE_TABLE="create table profiletable(profileid integer primary key autoincrement,profilename text null);";
public static final String VALUE_TABLE="create table valuetable(id integer primary key autoincrement,value text null,delay );";
*/
public RegistrationOpenHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, name, factory, version);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(SCRIPT);
db.execSQL(PROFILE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("drop table " + TABLE_NAME);
db.execSQL("drop table "+TABLE_NAME_ONE);
onCreate(db);
}
}