Kotlin ArrayAdapter 错误：无法使用提供的参数调用以下任何函数

Question

我是 Kotlin 的 Android 开发新手。在遵循教程项目时，我需要使用ArrayAdapter自定义类。构建项目失败并出现错误。

MainActivity.kt 类抛出错误：

    class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        setSupportActionBar(toolbar)
    }

    val dm = DataManager()
    val adapterCourses = ArrayAdapter<CourseInfo>(
        context = this,
        android.R.layout.simple_spinner_item,
        dm.courses.values.toList()
    )

    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        // Inflate the menu; this adds items to the action bar if it is present.
        menuInflater.inflate(R.menu.menu_main, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        return when (item.itemId) {
            R.id.action_settings -> true
            else -> super.onOptionsItemSelected(item)
        }
    }
}

错误：

None of the following functions can be called with the arguments supplied:
public constructor ArrayAdapter<T : Any!>(@RecentlyNonNull p0: Context!, p1: Int) defined in android.widget.ArrayAdapter
public constructor ArrayAdapter<T : Any!>(@RecentlyNonNull p0: Context!, p1: Int, @RecentlyNonNull p2: Array<(out) CourseInfo!>!) defined in android.widget.ArrayAdapter
public constructor ArrayAdapter<T : Any!>(@RecentlyNonNull p0: Context!, p1: Int, p2: Int) defined in android.widget.ArrayAdapter
public constructor ArrayAdapter<T : Any!>(@RecentlyNonNull p0: Context!, p1: Int, p2: Int, @RecentlyNonNull p3: Array<(out) CourseInfo!>!) defined in android.widget.ArrayAdapter
public constructor ArrayAdapter<T : Any!>(@RecentlyNonNull p0: Context!, p1: Int, p2: Int, @RecentlyNonNull p3: (Mutable)List<CourseInfo!>!) defined in android.widget.ArrayAdapter
public constructor ArrayAdapter<T : Any!>(@RecentlyNonNull p0: Context!, p1: Int, @RecentlyNonNull p2: (Mutable)List<CourseInfo!>!) defined in android.widget.ArrayAdapter

CourseInfo 类：

class CourseInfo (val courseId: String, val title: String)

数据管理器类：

class DataManager {
    val courses = HashMap<String, CourseInfo>()
    val notes = ArrayList<NoteInfo>()

    init {
        initializeCourses()
    }

    private fun initializeCourses () {
        var course = CourseInfo(courseId = "android_intent", title = "Android programming with intent.")
        this.courses.set(course.courseId, course)

        course = CourseInfo(courseId = "android_async", title = "Android Async Programming and Services.")
        courses.set(course.courseId, course)

        course = CourseInfo(courseId = "java_lang", title = "Java Fundamentals: The Java Language.")
        courses.set(course.courseId, course)

        course = CourseInfo(courseId = "java_core", title = "Java Fundamentals: The Core Platforms.")
        courses.set(course.courseId, course)
    }
}

Answer 1

也许为时已晚，但也许它可以帮助某人。如果您正在使用 Fragments，它不会被选中的答案解决。您必须像这样调用活动上下文。

val adapter = activity?.let {
        ArrayAdapter<String>(
            it,
            android.R.layout.simple_spinner_item,
            campaignsType
        )
    }

Answer 2

非 kotlin 函数不允许使用命名参数。

问题是因为您在 kotlin 文件中调用java ArrayAdapter构造函数。您将无法为其提供参数标签。

因此，进行简单的更正即可解决问题。（请注意，我删除了第一个参数中的上下文标签。）

val adapterCourses = ArrayAdapter<CourseInfo>(this,
            android.R.layout.simple_spinner_item,
            dm.courses.values.toList())