标签:android kotlin android-spinner android-arrayadapter
我试图在Fragment中创建一个Spinner,但我在ArrayAdapter构造函数调用中遇到错误.我不知道为什么,但它有一个红色下划线.除此之外,没有错误.当我在Activity中使用相同的ArrayAdapter时它可以工作,但是在Fragment中,它会出错.
我的FirstFragment.kt:
class FirstFragment : Fragment() {
private var mListener: OnFragmentInteractionListener? = null
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
// Inflate the layout for this fragment
return inflater!!.inflate(R.layout.fragment_first, container, false)
}
override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
/*Find the id of spinner*/
val spinner = lol
/*set an adapter with strings array*/
spinner.adapter = ArrayAdapter(this, R.layout.support_simple_spinner_dropdown_item, resources.getStringArray(R.array.atoms)) as SpinnerAdapter?
/*set click listener*/
spinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
override fun onItemSelected(parent: AdapterView<*>, view: View, position: Int, id: Long) {
val num = when (spinner.selectedItem.toString()) {
"H" -> editText.setText("1")
"He" -> editText.setText("4")
"C" -> editText.setText("12")
"O" -> editText.setText("16")
else -> editText.setText("")
}
}
override fun onNothingSelected(parent: AdapterView<*>) {
/*Do something if nothing selected*/
}
}
button.setOnClickListener {
if (
editText2.text.toString().length > 0 &&
editText.text.toString().length > 0) {
val num2 = editText.text.toString().toDouble()
val num1 = editText2.text.toString().toDouble()
val num = num1/num2
textView.setText("$num moles")
}
else {
textView.setText("Please Enter a correct value")
}
}
}
}
我的fragment_first.xml:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="com.a3.aakap.ftrial.FirstFragment">
<android.support.constraint.ConstraintLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:id="@+id/textView"
android:layout_width="294dp"
android:layout_height="80dp"
android:layout_weight="1"
android:text="Amswer : No of Moles"
android:textAlignment="center"
android:textSize="20sp"
app:layout_anchorGravity="right|top"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.556" />
<TextView
android:id="@+id/textView1"
android:layout_width="143dp"
android:layout_height="46dp"
android:layout_weight="1"
android:text="Amount in Grams "
android:textAlignment="center"
android:textSize="20sp"
app:layout_anchorGravity="left|bottom"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.066"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.305" />
<Spinner
android:id="@+id/lol"
android:layout_width="145dp"
android:layout_height="57dp"
app:layout_anchorGravity="left|top"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.07"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.136" />
<Button
android:id="@+id/button"
android:layout_width="138dp"
android:layout_height="43dp"
android:text="Calculate"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.788" />
<EditText
android:id="@+id/editText"
android:layout_width="148dp"
android:layout_height="57dp"
android:ems="10"
android:hint="Gram"
android:inputType="numberDecimal|number"
app:layout_anchorGravity="bottom|center"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.762"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.137" />
<EditText
android:id="@+id/editText2"
android:layout_width="148dp"
android:layout_height="57dp"
android:ems="10"
android:hint="Gram"
android:inputType="numberDecimal|number"
app:layout_anchorGravity="center_horizontal|center"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.716"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.288" />
</android.support.constraint.ConstraintLayout>
</FrameLayout>
解决方法:
问题出在这个构造函数调用中:
spinner.adapter = ArrayAdapter(
this,
R.layout.support_simple_spinner_dropdown_item,
resources.getStringArray(R.array.atoms)
) as SpinnerAdapter
参数必须是对Context的引用,而Fragment不是Context.在Activity中它起作用,因为Activity是一个Context.
解决方案是用活动替换它:
spinner.adapter = ArrayAdapter(
activity,
R.layout.support_simple_spinner_dropdown_item,
resources.getStringArray(R.array.atoms)
)
标签:android,kotlin,android-spinner,android-arrayadapter 来源: https://codeday.me/bug/20190828/1748871.html
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