为什么我这段代码会报错呢class ListViewTest : AppCompatActivity() { private val data = listOf("Apple","Banana","Orange","Watermelon", "Pear","Grape","Pineapple","Strawberry","Cherry","Mango", "Apple","Banana","Orange","Watermelon","Pear","Grape", "Pineapple","Strawberry","Cherry","Mango") override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.listview_layout) val adapter = ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,data) listView.adpter = adapter } }

可能是因为最后一行代码中的 "adpter" 拼写错误，应该改为 "adapter"。正确的代码如下：

class ListViewTest : AppCompatActivity() {
private val data = listOf("Apple","Banana","Orange","Watermelon",
"Pear","Grape","Pineapple","Strawberry","Cherry","Mango",
"Apple","Banana","Orange","Watermelon","Pear","Grape",
"Pineapple","Strawberry","Cherry","Mango")
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.listview_layout)
val adapter = ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,data)
listView.adapter = adapter
}
}

相关问题

为什么这段代码会报错：AttributeError: 'Mnist_NN' object has no attribute 'tain'

这个错误是因为在`fit`函数中的`model.train()`行，代码试图调用`Mnist_NN`对象的`tain`属性，但实际上这个对象并没有这样的属性。应该是误拼写了`train`方法，而不是`tain`。正确的语法应为`model.train()`，这表示设置模型处于训练模式，以便在接下来的迭代中启用正向传播和反向传播。

修复这个问题后，代码应该能正常运行。完整的修正后的`fit`函数应该是这样的：

def fit(steps, model, loss_func, opt, train_dl, valid_dl):
    for step in range(steps):
        model.train()  # 将这里修改为 'model.train()'
        for xb, yb in train_dl:
            loss_bach(model, loss_func, xb, yb, opt)
        model.eval()
        with torch.no_grad():
            losses, nums = zip(*[loss_bach(model, loss_func, xb, yb) for xb, yb in valid_dl])
        val_loss = np.sum(np.multiply(losses, nums)) / np.sum(nums)
        print('当前step：' + str(step), '验证集损失：' + str(val_loss))

    pass

现在，当模型进入训练模式时，将会执行期望的训练流程。

在scala中为何输入这一段代码会报错：class Person private(val name: String) { private def getSkill() = name + "'s skill is: " + Person.skill }

在Scala中，如果将构造函数声明为私有（private），则只能在类的内部访问它。这意着在类的外部无法直接实例化该类。因此，如果你尝试使用私有构造函数来创建Person类的对象，会导致编译错误。

如果你想在类的外部创建Person对象，可以考虑使用伴生对象的工厂方法来创建。通过在伴生对象中定义一个公共的方法来创建对象，可以绕过私有构造函数的限制。

下面是一个示例，展示了如何在Scala中使用伴生对象的工厂方法来创建Person对象：

class Person private(val name: String) {
  private def getSkill() = name + "'s skill is: " + Person.skill
}

object Person {
  private val skill = "Programming"

  def create(name: String): Person = {
    new Person(name)
  }
}

通过调用`Person.create("John")`方法，将会返回一个名为"John"的Person对象。