我正在使用我使用sqlitebrowser创建的预先填充的slqite数据库。
我已将数据库文件（它似乎没有扩展名）放入我的资源文件夹中。
我正在使用每个人似乎都在使用的标准databasehelper类。
05-09 13:04:55.746 894-894/com.myapp.myappname E/CursorWindow﹕ Failed to read row 0, column 1 from a CursorWindow which has 19 rows, 1 columns.
05-09 13:04:55.766 894-894/com.myapp.myappname D/AndroidRuntime﹕ Shutting down VM
05-09 13:04:55.766 894-894/com.myapp.myappname W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x40a71930)
05-09 13:04:55.876 894-894/com.myapp.myappname E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.myappname/com.myapp.myappname.MainActivity}: java.lang.IllegalStateException: Couldn't read row 0, col 1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalStateException: Couldn't read row 0, col 1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.database.CursorWindow.nativeGetString(Native Method)
at android.database.CursorWindow.getString(CursorWindow.java:434)
at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:51)
at com.myapp.myappname.DataBaseHelper.getAllOccasions(DataBaseHelper.java:193)
at com.myapp.myappname.MainActivity.loadOccasionSpinnerData(MainActivity.java:155)
at com.myapp.myappname.MainActivity.onCreate(MainActivity.java:72)
at android.app.Activity.performCreate(Activity.java:5104)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)
这是我的数据库助手类：
它在课堂上的这一行失败了：
Cursor cursor = db.rawQuery(selectQuery, null);
这是班级：
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import java.io.FileOutputStream;
import java.io.IOException;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
public class DataBaseHelper extends SQLiteOpenHelper {
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.myapp.myappname/databases/";
private static String DB_NAME = "WTWDatabase";
private SQLiteDatabase myDataBase;
private final Context myContext;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 1);
if(android.os.Build.VERSION.SDK_INT >= 17){
DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
}
else
{
DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
}
this.myContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}else{
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
//Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
// Add your public helper methods to access and get content from the database.
// You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
// to you to create adapters for your views.
/**
* Getting all labels
* returns list of labels
* */
public List<String> getAllOccasions(){
List<String> labels = new ArrayList<String>();
// Select All Query
String selectQuery = "SELECT Occasion FROM Occasions";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null); //FAILS HERE
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
labels.add(cursor.getString(1));
} while (cursor.moveToNext());
}
// closing connection
cursor.close();
db.close();
// returning lables
return labels;
}
public List<String> getAllSubCategories(String Occasion){
List<String> labels = new ArrayList<String>();
// Select All Query
String selectQuery = "Select subcategory from subcategory where Occasionkey = (select _id from Occasions where Occasion = '" + Occasion + "')";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
labels.add(cursor.getString(1));
} while (cursor.moveToNext());
}
// closing connection
cursor.close();
db.close();
// returning lables
return labels;
}
public List<String> getAllMessages(String Occasion, String SubCategory){
List<String> labels = new ArrayList<String>();
// Select All Query
String selectQuery = "Select Message from Messages INNER JOIN\n" +
"MessageSubCategory ON MessageSubCategory.MessageKey = Messages._id\n" +
" where Messages.OccasionKey = (select _id from Occasions where Occasion = '\" + Occasion + \"')\n" +
"AND MessageSubCategory.SubCategoryKey = (select SubCategory._id from SubCategory where SubCategory.Subcategory = '\" + SubCategory + \"')";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
labels.add(cursor.getString(1));
} while (cursor.moveToNext());
}
// closing connection
cursor.close();
db.close();
// returning lables
return labels;
}
}
答案 0 :(得分：31)
列索引从0开始。您的游标只有1列，因此将getString(1)替换为getString(0)以访问唯一的列值。
答案 1 :(得分：2)
请在编写以下代码之前添加以下一行。
if(cursor!=null && cursor.getCount() > 0)
{
if (cursor.moveToFirst())
{
do {
labels.add(cursor.getString(1));
} while (cursor.moveToNext());
}
}
因为，当游标为空并且你从游标获得值时，它会给出错误。
请尝试提供反馈。
答案 2 :(得分：1)
增加数据库版本对我有用。
答案 3 :(得分：0)
更好地尝试使用cursor.getColumnIndex()而不是整数从Sqlite数据库中获取特定值，如下所示
if(cursor!=null && cursor.getCount() > 0) {
if (cursor.moveToFirst()) {
do {
labels.add(cursor.getColumnIndex(YOUR_DB_COLUMN_NAME));
} while (cursor.moveToNext());
cursor.close();
}
}