无法读取0行，列-1

2023-09-07 14:24:01 作者：绾青丝

我试图复制我的SQLite的经理做了一个数据库，其中我所做的：

  CREATE TABLEandroid_metadata（区域设置TEXT DEFAULT'EN_US'）

和

  INSERT INTOandroid_metadataVALUES（'EN_US'）

和我命名我的所有主键 _id 。我的数据库被复制（在第一次运行中有各种logcat中红色消息）;此后，它只是提供了一个错误，当我查询。

MainActivity

 公共类MainActivity延伸活动{字符串CNAME =疑问句，TABLE_NAME =JAVAQ;@覆盖公共无效的onCreate（捆绑savedInstanceState）{    super.onCreate（savedInstanceState）;    的setContentView（R.layout.activity_main）;    Setupdb dbobj =新Setupdb（本）;    尝试{        //dbobj.close（）;        dbobj.createDataBase（）;    }赶上（IOException异常五）{        // TODO自动生成catch块        e.printStackTrace（）;    }    dbobj.openDataBase（）;    dbobj.close（）;   尝试{         SQLiteDatabase sqdb = dbobj.getReadableDatabase（）;         光标C = sqdb.query（TABLE_NAME，                 新的String [] {} CNAME，                 NULL，NULL，NULL，NULL，NULL）;         而（c.moveToNext（））{            字符串名称=            c.getString（c.getColumnIndex（CNAME））;            Log.i（LOG_TAG，HAS名+姓名）;         }}            赶上（例外五）{                Log.e（犯错，e.toString（））;            }}}

Setupdb

 公共类Setupdb扩展SQLiteOpenHelper {  私人静态字符串DB_PATH =;    私有静态最后弦乐DB_NAME =凸轮prep.sqlite    私人SQLiteDatabase MYDATABASE;    私人最终上下文myContext;    私有静态Setupdb mDBConnection;公共Setupdb（上下文的背景下）{    超级（上下文，DB_NAME，空，3）;    this.myContext =背景;    DB_PATH =/数据/数据/            + context.getApplicationContext（）。getPackageName（）            +/数据库/;    Log.e（DB_NAME，DB_PATH）;}同步Setupdb getDBAdapterInstance（上下文的背景下）公共静态{    如果（mDBConnection == NULL）{        mDBConnection =新Setupdb（背景）;    }    返回mDBConnection;}    公共无效的CreateDatabase（）抛出IOException        布尔dbExist = checkDataBase（）;        如果（dbExist）{            Log.e（DB，存在）;            //什么也不做 - 已存在于数据库        }其他{            //通过调用下面的方法            // 1）一个空数据库将被创建到应用程序的默认系统路径            // 2）比我们覆盖我们的数据库，该数据库。            this.getReadableDatabase（）;            尝试{                Log.e（调用，复制）;                copyDataBase（）;            }赶上（IOException异常五）{                抛出新的错误（错误复制数据库）;            }        }}    私人布尔checkDataBase（）{        SQLiteDatabase CHECKDB = NULL;        尝试{            字符串mypath中= DB_PATH + DB_NAME;            CHECKDB = SQLiteDatabase.openDatabase（mypath中，空，                    SQLiteDatabase.OPEN_READONLY）;        }赶上（SQLiteException E）{            //数据库开不存在。        }        如果（CHECKDB！= NULL）{            checkDB.close（）;        }        返回CHECKDB！= NULL？真假;    }    私人无效copyDataBase（）抛出IOException        //打开本地数据库的输入流    InputStream的myInput = myContext.getAssets（）开（DB_NAME）。        //路径刚刚创建的空分贝    字符串outFileName = DB_PATH + DB_NAME;        //打开空分贝的输出流    的OutputStream myOutput =新的FileOutputStream（outFileName）;        //传递从inputfile中字节到OUTPUTFILE    字节[]缓冲区=新的字节[1024];    INT长;    而（（长度= myInput.read（缓冲液））大于0）{        myOutput.write（缓冲液，0，长度）;    }        //关闭流    myOutput.flush（）;    myOutput.close（）;    myInput.close（）;}    公共无效的openDatabase（）抛出的SQLException {        字符串mypath中= DB_PATH + DB_NAME;        MYDATABASE = SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READWRITE）;    }    公共同步无效的close（）{        如果（MYDATABASE！= NULL）            myDataBase.close（）;        super.close（）;    }@覆盖公共无效的onCreate（SQLiteDatabase DB）{    // TODO自动生成方法存根}@覆盖公共无效onUpgrade（SQLiteDatabase分贝，INT oldVersion，诠释静态网页）{}}

堆栈跟踪

  20 08-31：17：05.320：I / dalvikvm（9457）：主题ID = 3：反应信号308-31 20：17：05.370：I / dalvikvm（9457）：写的堆栈跟踪到/data/anr/traces.txt08-31 20：17：05.451：E /凸轮prep.sqlite（9457）：/data/data/com.example.mydataexplosion/databases/08-31 20：17：05.490：E / DB（9457）：存在08-31 20：17：05.521：E / CursorWindow（9457）：无法读取0行，列-1由具有11行，1列的CursorWindow。08-31 20：17：05.521：E / ERR（9457）：java.lang.IllegalStateException：无法读取0行，列-1从CursorWindow。确保光标从它访问数据之前正确初始化。08-31 20：17：05.650：D / gralloc_goldfish（9457）：无仿真模拟GPU检测。08-31 20：17：05.650的：I / dalvikvm（9457）：主题ID = 3：反应以信号308-31 20：17：05.670：I / dalvikvm（9457）：写的堆栈跟踪到/data/anr/traces.txt

解决方案

如果你看到

 无法读取0行，列-1

这意味着你正试图从一个不存在的列来读取。

如果它不能找到您指定的列名， Cursor.getColumnIndex（）收益 1 ，因此，是无效的。

有两个原因：

列不存在。列的名称不正确。（所以不存在）。

注：列名的区分大小写当使用 getColumnIndex（）

在您的方案：

  c.getString（c.getColumnIndex（CNAME））;

检查CNAME变量的拼写是否正确，而该名称的列存在。

 字符串CNAME =疑问句

如果额外的前导空格在那里例如..

I am trying to copy a database that I made with SQLite manager, in which I did:

CREATE TABLE "android_metadata" ("locale" TEXT DEFAULT 'en_US')

and

INSERT INTO "android_metadata" VALUES ('en_US')

And I named all my primary keys _id. My database gets copied(in the first run there are various red messages in the logcat); thereafter, it only gives an error when I query it.

MainActivity

public class MainActivity extends Activity {
String CNAME=" ques",TABLE_NAME=" JAVAQ";




@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Setupdb dbobj=new Setupdb(this); 

    try {    

        //dbobj.close();
        dbobj.createDataBase();

    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } 



    dbobj.openDataBase();
    dbobj.close();



   try{
         SQLiteDatabase sqdb=dbobj.getReadableDatabase();



         Cursor c = sqdb.query(TABLE_NAME,
                 new String[] { CNAME },
                 null, null, null, null, null); 
         while (c.moveToNext()) {

            String name =
            c.getString(c.getColumnIndex(CNAME));
            Log.i("LOG_TAG", " HAS NAME " + name);
         }}



            catch(Exception e){

                Log.e("err", e.toString());
            } 




}}

Setupdb

public class Setupdb extends SQLiteOpenHelper {

  private static String DB_PATH = "";
    private static final String DB_NAME = "camprep.sqlite";
    private SQLiteDatabase myDataBase;
    private final Context myContext;

    private static Setupdb mDBConnection;


public Setupdb(Context context) {
    super(context, DB_NAME, null, 3);
    this.myContext=context;
    DB_PATH="/data/data/"
            + context.getApplicationContext().getPackageName()
            + "/databases/";
    Log.e(DB_NAME, DB_PATH);
}
public static synchronized Setupdb getDBAdapterInstance(Context context) {
    if (mDBConnection == null) {
        mDBConnection = new Setupdb(context);
    }
    return mDBConnection;
} 

    public void createDataBase() throws IOException {

        boolean dbExist = checkDataBase();
        if (dbExist) {
            Log.e("db","exist");
            // do nothing - database already exist
        } else {
            // By calling following method
            // 1) an empty database will be created into the default system path of your application
            // 2) than we overwrite that database with our database.
            this.getReadableDatabase();
            try {
                Log.e("calling", "copy");
                copyDataBase(); 
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }





}
    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; 
    }

    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 {
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
    }
    public synchronized void close() {
        if (myDataBase != null)
            myDataBase.close();
        super.close();
    } 

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {


}

}

Stacktrace

 08-31 20:17:05.320: I/dalvikvm(9457): threadid=3: reacting to signal 3
08-31 20:17:05.370: I/dalvikvm(9457): Wrote stack traces to '/data/anr/traces.txt'
08-31 20:17:05.451: E/camprep.sqlite(9457): /data/data/com.example.mydataexplosion/databases/
08-31 20:17:05.490: E/db(9457): exist
08-31 20:17:05.521: E/CursorWindow(9457): Failed to read row 0, column -1 from a CursorWindow which has 11 rows, 1 columns.
08-31 20:17:05.521: E/err(9457): java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
08-31 20:17:05.650: D/gralloc_goldfish(9457): Emulator without GPU emulation detected.
08-31 20:17:05.650: I/dalvikvm(9457): threadid=3: reacting to signal 3
08-31 20:17:05.670: I/dalvikvm(9457): Wrote stack traces to '/data/anr/traces.txt'

解决方案

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