Question

我正在尝试在android上使用sqlite数据库.Below是我用来访问sqlite数据库的SQL帮助程序类。

public class SQLHelper extends SQLiteOpenHelper{
static final String TABLE_NAME = "itemDetail";
static final String ID  ="id INTEGER PRIMARY KEY AUTOINCREMENT";
static final String ITEM = "item";
static final String QUANTITY = "quantity";
static final String CREATE_TABLE = "CREATE TABLE "+SQLHelper.TABLE_NAME+"( " + ID +" , "+SQLHelper.ITEM+" TEXT "+" , "+SQLHelper.QUANTITY+" INTEGER"+" )";
static final String DB_NAME = "mydb";

public SQLHelper(Context context, int version) {
    super(context, DB_NAME, null, 1);
    // TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase arg0) {
    // TODO Auto-generated method stub
    arg0.execSQL(CREATE_TABLE);
}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    // TODO Auto-generated method stub
    arg0.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);

    // create fresh books table
    this.onCreate(arg0);
}



public long add(String item , String q){

    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(ITEM, item);
    values.put(QUANTITY , q);
    long newr = db.insert(TABLE_NAME,  "null", values);

    db.close();
    return newr;
}
public Cursor read(){
    Cursor cc;
    SQLiteDatabase db = this.getWritableDatabase();
    Log.d("report","ok");
    cc=db.rawQuery("SELECT * FROM itemDetail", null);
    Log.d("report","ok2");
    db.close();
    //cc.moveToFirst();
    Log.d("good",cc.getString(1));
    return cc;

}

}

当我使用cc（Cursor对象）访问查询命令返回的行时，我的程序停止。我认为rawQuery没有返回任何行。请帮助。谢谢

logcat的

 01-13 22:12:37.921: E/AndroidRuntime(341): Caused by:        android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 23
 01-13 22:12:37.921: E/AndroidRuntime(341):     at android.database.AbstractCursor.checkPosition(AbstractCursor.java:580)
 01-13 22:12:37.921: E/AndroidRuntime(341):     at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:214)
 01-13 22:12:37.921: E/AndroidRuntime(341):     at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:41)
  01-13 22:12:37.921: E/AndroidRuntime(341):    at it.is.appone.SQLHelper.read(SQLHelper.java:63)
 01-13 22:12:37.921: E/AndroidRuntime(341):     at it.is.appone.Report.show(Report.java:36)
  01-13 22:12:37.921: E/AndroidRuntime(341):    ... 14 more

下面是我试图访问数据库的活动类中的函数。

public void show(View view){
    //Toast.makeText(this, "in show", 5000).show();
    SQLHelper myh = new SQLHelper(this,dbversion);
    SQLiteCursor cc=(SQLiteCursor) myh.read();
    //readDB();

    Log.d("Report5"," in report");
    String text = new String();
    try{
    if(cc != null){
       cc.moveToFirst();
       text = cc.getString(1);
    }
    else
    {
        text = "bad";
    }
    }catch(Exception e){
        Toast.makeText(this, e.getMessage(), 5000);
    }

    Log.d("report data base", text );

    /*while (!cc.isAfterLast()){
        String t = cc.getString(cc.getColumnIndexOrThrow(SQLHelper.ITEM));
        text = text +  t;
    }*/
    //Toast.makeText(this, "everthing ok", 5000).show();

}

Answer 1

请检查游标总是不应为null，为此目的使用以下代码...

if (cursor != null)
        cursor.moveToFirst();

你关闭了

db.close();

在获取游标之前

。关闭游标后关闭数据库

请发送有关logcat和确切问题的更多信息

尝试访问数据库时sqlite android中的错误

1 个答案: