我该如何解决：java.util.UnknownFormatConversionException：Conversion ='''？

Question

我是Android工作室的新手，我最近一直在开发一个应用程序，允许您下订单，并为了订购您添加的东西到购物车，然后可以从您的帐户页面查看详细信息。单击购物车或尝试将项目添加到购物车时，应用程序崩溃并显示：

E/AndroidRuntime: FATAL EXCEPTION: main
  Process: com.sakaaz.sakaaz, PID: 30731
  java.util.UnknownFormatConversionException: Conversion = '''
      at java.util.Formatter$FormatSpecifier.conversion(Formatter.java:2730)
      at java.util.Formatter$FormatSpecifier.<init>(Formatter.java:2759)
      at java.util.Formatter$FormatSpecifierParser.<init>(Formatter.java:2591)
      at java.util.Formatter.parse(Formatter.java:2524)
      at java.util.Formatter.format(Formatter.java:2472)
      at java.util.Formatter.format(Formatter.java:2426)
      at java.lang.String.format(String.java:2626)
      at edmt.dev.androidsakaaz.Database.Database.addToCart(Database.java:55)
      at edmt.dev.androidsakaaz.MakeupDetail$1.onClick(MakeupDetail.java:59)
      at android.view.View.performClick(View.java:6257)
      at android.view.View$PerformClick.run(View.java:23705)
      at android.os.Handler.handleCallback(Handler.java:751)
      at android.os.Handler.dispatchMessage(Handler.java:95)
      at android.os.Looper.loop(Looper.java:154)
      at android.app.ActivityThread.main(ActivityThread.java:6836)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)

我不知道出了什么问题。这是我的数据库类：

public class Database extends SQLiteAssetHelper {

    private static final String DATABASE_NAME = "sakaazDB.db";
    private static final int DB_VER=1;


    public Database(Context context) {
        super( context, DATABASE_NAME, null , DB_VER );
    }

    public List<Order> getCarts()
    {
        SQLiteDatabase db=getReadableDatabase();
        SQLiteQueryBuilder qb= new SQLiteQueryBuilder();

        String[] sqlSelect={"ProductName", "ProductId", "Quantity", "Price", "Discount"};
        String sqlTable="OrderDetail";

        qb.setTables( sqlTable );
        Cursor c = qb.query(db,sqlSelect,null,null,null,null,null);

        final List<Order> result = new ArrayList<>();
        if (c.moveToFirst())
        {
            do{
                result.add( new Order( c.getString(c.getColumnIndex("ProductId")),
                        c.getString(c.getColumnIndex("ProductName")),
                        c.getString(c.getColumnIndex("Quantity")),
                        c.getString(c.getColumnIndex("Price")),
                        c.getString(c.getColumnIndex("Discount"))
                        ));
            }while (c.moveToNext());
        }
        return result;
    }

    public void addToCart (Order order)
    {
        SQLiteDatabase db = getReadableDatabase();
        String query = String.format("INSERT INTO OrderDetail(ProductId, ProductName, Quantity, Price, Discount) VALUES ('s%','s%','s%','s%','s%');",
                order.getProductId(),
                order.getProductName(),
                order.getQuantity(),
                order.getPrice(),
                order.getDiscount());

        db.execSQL(query);
    }

    public void cleanCart()
    {
        SQLiteDatabase db = getReadableDatabase();
        String query = String.format("DELETE FROM OrderDetail");
        db.execSQL(query);
    }
}

请帮忙！！

Answer 1

如果未设置任何变量参数，则无需使用String.format（）。在cleanCart（）方法中，将第2行替换为：String query =“DELETE FROM OrderDetail”;

另外，您应该使用getWritableDatabase（）来获取数据库对象，因为您实际上正在写入它。

编辑：用这个替换你的addToCart（）方法。

public void addToCart (Order order)
{
    SQLiteDatabase db = getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put("ProductId", order.getProductId();
    values.put("ProductName", order.getProductName();
    values.put("Quantity", order.getQuantity();
    values.put("Price", order.getPrice();
    values.put("Discount", order.getDiscount();
    db.insert("OrderDetail", null, values);
}