android - 如何在 Activity OnCreate 上设置片段？ （科特林）

Question

我目前正在开发具有设置活动的应用程序。在这个 Activity 中，有一个 FrameLayout，用于加载 Settings Main 片段。

当我尝试使用包含 supportFragmentManager 的函数在活动的 onCreate 中加载片段时，我收到错误 Unable to start activity: java.lang.IllegalStateException: Fragment not attached to a context。奇怪的是，Android Studio 指向val frgSettingsMain = FragmentSettingsMain() 和DataItemsSettings。

我做错了什么？还有其他更简洁的方法可以在 onCreate 中初始化 Fragment 吗？

代码：

ActivitySettings.kt

class ActivitySettings : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_settings)

        topToolbarBack.setNavigationOnClickListener {
            finish()
        }

        val frgSettingsMain = FragmentSettingsMain()

        setCurrentFragment(frgSettingsMain)

    }

    private fun setCurrentFragment(fragment: Fragment) =
        supportFragmentManager.beginTransaction().apply {
            replace(R.id.framelayoutSettings, fragment)
            commit()
        }
}

FragmentSettingsMain.kt

class FragmentSettingsMain : Fragment(), AdapterSettings.OnItemClickListener {
    val settingsList = listOf(
        DataItemsSettings(getString(R.string.look), getString(R.string.lookdescription), R.drawable.ic_colored_color_lens),
        DataItemsSettings(getString(R.string.playing), getString(R.string.playingdescription), R.drawable.ic_colored_view_carousel),
        DataItemsSettings(getString(R.string.images), getString(R.string.imagesdscription), R.drawable.ic_colored_image),
        DataItemsSettings(getString(R.string.audio), getString(R.string.audiodescription), R.drawable.ic_colored_volume_up),
        DataItemsSettings(getString(R.string.other), getString(R.string.otherdescription), R.drawable.ic_colored_shape),
        DataItemsSettings(getString(R.string.about), getString(R.string.aboutdescription), R.drawable.ic_colored_info)
    )

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        retainInstance = true
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? = inflater.inflate(R.layout.fragment_settings_main, container, false)

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        rvSettings.apply {
            layoutManager = LinearLayoutManager(activity)
            adapter = AdapterSettings(settingsList, this@FragmentSettingsMain)
        }
    }

    override fun OnItemClick(position: Int) {
        when(position) {
            0 -> Toast.makeText(context, "Pressed Option 0", Toast.LENGTH_LONG).show()
            1 -> Toast.makeText(context, "Pressed Option 1", Toast.LENGTH_LONG).show()
            2 -> Toast.makeText(context, "Pressed Option 2", Toast.LENGTH_LONG).show()
            3 -> Toast.makeText(context, "Pressed Option 3", Toast.LENGTH_LONG).show()
            4 -> Toast.makeText(context, "Pressed Option 4", Toast.LENGTH_LONG).show()
            5 -> Toast.makeText(context, "Pressed Option 5", Toast.LENGTH_LONG).show()
        }
    }
}

Answer 1

问题是getstring() 方法需要上下文。当您调用 FragmentSettingsMain() 时，上下文不会附加到 Fragment。尝试在将 Fragment 添加到容器后初始化变量 settingsList。例如：

lateinit var settingsList : List<DataItemSettings>
override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        retainInstance = true
        settingsList = listOf(
        DataItemsSettings(getString(R.string.look), getString(R.string.lookdescription), R.drawable.ic_colored_color_lens),
        DataItemsSettings(getString(R.string.playing), getString(R.string.playingdescription), R.drawable.ic_colored_view_carousel),
        DataItemsSettings(getString(R.string.images), getString(R.string.imagesdscription), R.drawable.ic_colored_image),
        DataItemsSettings(getString(R.string.audio), getString(R.string.audiodescription), R.drawable.ic_colored_volume_up),
        DataItemsSettings(getString(R.string.other), getString(R.string.otherdescription), R.drawable.ic_colored_shape),
        DataItemsSettings(getString(R.string.about), getString(R.string.aboutdescription), R.drawable.ic_colored_info)
    )

    }