Question

我在表单中有一个嵌套集合：

HashMap<String, HashMap<String, List<String>>> errorList;

现在我使用像这样的双括号内联初始化它

errorList.put(tempName, new HashMap<String, List<String>>() {{
    put("upl", new ArrayList<String>() {{ add("Y"); add("Upload Success"); }});
}});

这位于foreach循环中，tempName的值在每次迭代中都会发生变化。我这样做是因为我无法使用List<String>或HashMap<String,List<String>>的实例，因为每次我更改该实例中的值时，它都会反映在它嵌套的集合中。所以我被迫创建新的双括号初始化的实例。

事情是：我想使用列表对象。而不是

new ArrayList<String>() {{ add("Y"); add("Upload Success"); }}

我想使用变量。

我该怎么做？

Answer 1

而不是

            Random rand = new Random();
            int RandomOne = rand.Next(0, 10);
            int RandomTwo = rand.Next(0, 10);
            int RandomThree = rand.Next(0, 10);
            int RandomFour = rand.Next(0, 10);
            int RandomFive = rand.Next(0, 10);
            int RandomSix = rand.Next(0, 10);
            int RandomSeven = rand.Next(0, 10);
            int RandomEight = rand.Next(0, 10);
            int RandomNine = rand.Next(0, 10);
            int RandomZero = rand.Next(0, 10);

            btnOneNgra.Text = Convert.ToString(RandomOne);


            if ((RandomTwo == RandomOne) || (RandomTwo == RandomNine) || (RandomTwo == RandomThree) || (RandomTwo == RandomFour)
                || (RandomTwo == RandomFive) || (RandomTwo == RandomSix) || (RandomTwo == RandomSeven) || (RandomTwo == RandomEight) || (RandomTwo == RandomZero))
            {
                RandomTwo = rand.Next(0, 10);
            }
            else 
            {
                btnTwoNgra.Text = Convert.ToString(RandomTwo);
            }


            if ((RandomThree == RandomOne) || (RandomThree == RandomTwo) || (RandomThree == RandomNine) || (RandomThree == RandomFour)
                || (RandomThree == RandomFive) || (RandomThree == RandomSix) || (RandomThree == RandomSeven) || (RandomThree == RandomEight) || (RandomThree == RandomZero))
            {
                RandomThree = rand.Next(0, 10);
            }
            else
            {
                btnThreeNgra.Text = Convert.ToString(RandomThree);
            }


            if ((RandomFour == RandomOne) || (RandomFour == RandomTwo) || (RandomFour == RandomThree) || (RandomFour == RandomNine)
                || (RandomFour == RandomFive) || (RandomFour == RandomSix) || (RandomFour == RandomSeven) || (RandomFour == RandomEight) || (RandomFour == RandomZero))
            {
                RandomFour = rand.Next(0, 10);
            }
            else
            {
                btnFourNgra.Text = Convert.ToString(RandomFour);
            }


            if ((RandomFive == RandomOne) || (RandomFive == RandomTwo) || (RandomFive == RandomThree) || (RandomFive == RandomFour)
                || (RandomFive == RandomNine) || (RandomFive == RandomSix) || (RandomFive == RandomSeven) || (RandomFive == RandomEight) || (RandomFive == RandomZero))
            {
                RandomFive = rand.Next(0, 10);
            }
            else
            {
                btnFiveNgra.Text = Convert.ToString(RandomFive);
            }


            if ((RandomSix == RandomOne) || (RandomSix == RandomTwo) || (RandomSix == RandomThree) || (RandomSix == RandomFour)
                || (RandomSix == RandomFive) || (RandomSix == RandomNine) || (RandomSix == RandomSeven) || (RandomSix == RandomEight) || (RandomSix == RandomZero))
            {
                RandomSix = rand.Next(0, 10);
            }
            else
            {
                btnSixNgra.Text = Convert.ToString(RandomSix);
            }


            if ((RandomSeven == RandomOne) || (RandomSeven == RandomTwo) || (RandomSeven == RandomThree) || (RandomSeven == RandomFour)
                || (RandomSeven == RandomFive) || (RandomSeven == RandomSix) || (RandomSeven == RandomNine) || (RandomSeven == RandomEight) || (RandomSeven == RandomZero))
            {
                RandomSeven = rand.Next(0, 10);
            }
            else
            {
                btnSevenNgra.Text = Convert.ToString(RandomSeven);
            }


            if ((RandomEight == RandomOne) || (RandomEight == RandomTwo) || (RandomEight == RandomThree) || (RandomEight == RandomFour)
                || (RandomEight == RandomFive) || (RandomEight == RandomSix) || (RandomEight == RandomSeven) || (RandomEight == RandomNine) || (RandomEight == RandomZero))
            {
                RandomEight = rand.Next(0, 10);
            }
            else
            {
                btnEightNgra.Text = Convert.ToString(RandomEight);
            }


            if ((RandomNine == RandomOne) || (RandomNine == RandomTwo) || (RandomNine == RandomThree) || (RandomNine == RandomFour)
                || (RandomNine == RandomFive) || (RandomNine == RandomSix) || (RandomNine == RandomSeven) || (RandomNine == RandomEight) || (RandomNine == RandomZero))
            {
                RandomNine = rand.Next(0, 10);
            }
            else 
            {
                btnNineNgra.Text = Convert.ToString(RandomNine);
            }


            if ((RandomZero == RandomOne) || (RandomZero == RandomTwo) || (RandomZero == RandomThree) || (RandomZero == RandomFour)
                || (RandomZero == RandomFive) || (RandomZero == RandomSix) || (RandomZero == RandomSeven) || (RandomZero == RandomEight) || (RandomZero == RandomNine))
            {
                RandomZero = rand.Next(0, 10);
            }
            else
            {
                btnZeroNgra.Text = Convert.ToString(RandomZero);
            }

你可以使用

string script = @
    "<script type='text/javascript'>
        alert('Booking Complete! Thank you for choosing Euro-City-Tours');
    </script>";

ClientScript.RegisterClientScriptBlock(this.GetType(), "Alert", script);

这为您提供了固定大小的列表。如果您希望以后能够添加或删除元素，请将其转换为new ArrayList<String>() {{ add("Y"); add("Upload Success"); }}：

Arrays.asList("Y", "Upload Success")

当然，在将其放入地图结构之前，您可以将此列表放入其自己的变量中。

如果你想要放置ArrayList或new ArrayList<>(Arrays.asList("Y", "Upload Success"))并确保列表不在地图条目之间共享，这里有一个建议：首先，在你的循环之外：

[Y, Upload Success]

然后在你的循环中

[N, Upload Failed]

您可以更进一步，并在循环外构建地图。同样，如果您希望内部地图为final List<String> successList = Arrays.asList("Y", "Upload Success"); final List<String> failureList = Arrays.asList("N", "Upload Failed");，只需转换为一个：if (wasSuccessful) { errorList.put(tempName, Collections.singletonMap("upl", new ArrayList<>(successList))); } else { errorList.put(tempName, Collections.singletonMap("upl", new ArrayList<>(failureList))); }。

我还没有测试过这段代码，希望你能解决这个问题。

你注意到我完全避免了双括号初始化。虽然它很简短，但它在概念和性能方面都有开销。你每次都在创建一个新的匿名子类，我认为这是不合理的。

替代双支撑初始化

1 个答案: