android - sqlite中cursor的问题
天蓬老师
天蓬老师 2017-04-17 16:02:11
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我建立了一个表public static final String CREATE_BOOK = "create table Book(" + "id integer primary key autoincrement," + "author text," + "price real," + "pages integer," + "name text," + "category_id integer)";
之后建立了一个Button传入数据

add_data.setOnClickListener(new View.OnClickListener() {
     @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbhelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("author", "jose");
                values.put("name", "Thank you!");
                values.put("pages", 999);
                values.put("price", 99.9);
                db.insert("Book", null, values);    }
        });           

之后建立另一个按钮用来索引表

query_data.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbhelper.getWritableDatabase();
                Cursor cursor = db.query("Book", null, null, null, null, null, null);
                if(cursor.moveToFirst()){
                    do {
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        String author = cursor.getString(cursor.getColumnIndex("author"));
                        int pages = cursor.getInt(cursor.getColumnIndex("pages"));
                        double price = cursor.getDouble(cursor.getColumnIndex("price"));
                        Log.d("MainActivity", "book name is" + name);
                        Log.d("MainActivity", "book author is" + author);
                        Log.d("MainActivity", "book pages is" + pages);
                        Log.d("MainActivity", "book prices is" + price);
                    }while (cursor.moveToNext());
                }
                cursor.close();
            }
        });

但是调试时报错Failed to read row 0, column -1 from a CursorWindow which has 1 rows, 5 columns. Make sure the Cursor is initialized correctly before accessing data from it.
我将传入数据时的name和author的顺序交换之后发现就可以运行了,请教一下各位大神这是什么原因?

天蓬老师
天蓬老师

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