片段类型不匹配

Question

我正在开发 Android 应用程序，它使用 Zxing 扫描片段上的二维码，为了实现这一点，我按照本教程获得了想要的结果。Link I Followed to Scan QR on Fragment

我用来在 **QRCodeFragment ** 片段上扫描 QR 的代码看起来

class QRCodeFragment : Fragment() {

internal var txtName: TextView? = null
internal var txtSiteName: TextView? = null
internal var btnScan: Button? = null
internal var qrScanIntegrator: IntentIntegrator? = null


override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    return inflater?.inflate(R.layout.fragment_qr_code, container, false)
}


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

    txtName = view.findViewById(R.id.name)
    txtSiteName = view.findViewById(R.id.site_name)

    btnScan = view.findViewById(R.id.btnScan)
    btnScan!!.setOnClickListener { performAction() }

    qrScanIntegrator = IntentIntegrator.forFragment(this)
    qrScanIntegrator?.setOrientationLocked(false)

    // Different Customization option...
    qrScanIntegrator?.setPrompt(getString(R.string.scan_a_code))
    qrScanIntegrator?.setCameraId(0)  // Use a specific camera of the device
    qrScanIntegrator?.setBeepEnabled(false)
    qrScanIntegrator?.setBarcodeImageEnabled(true)

    super.onViewCreated(view, savedInstanceState)
}

private fun performAction() {
    qrScanIntegrator?.initiateScan()
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    val result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data)
    if (result != null) {
        // If QRCode has no data.
        if (result.contents == null) {
            Toast.makeText(activity, R.string.result_not_found, Toast.LENGTH_LONG).show()
        } else {
            // If QRCode contains data.
            try {
                // Converting the data to json format
                val obj = JSONObject(result.contents)
                // Show values in UI.
                txtName?.text = obj.getString("name")
                txtSiteName?.text = obj.getString("site_name")

            } catch (e: JSONException) {
                e.printStackTrace()

                // Data not in the expected format. So, whole object as toast message.
                Toast.makeText(activity, result.contents, Toast.LENGTH_LONG).show()
            }

        }
    } else {
        super.onActivityResult(requestCode, resultCode, data)
    }
}

}

来自 Main Activity 我正在调用 Fragment 就像

    private fun ShowQRCodeFragment() {
    val newFragment = QRCodeFragment()
    val transaction1: FragmentTransaction = supportFragmentManager.beginTransaction();
    transaction1.replace(R.id.frameLayout, newFragment);
    transaction1.addToBackStack(null);
    transaction1.commit();
}

在主片段中它显示类型不匹配，我指着它转到正在扩展 Fragment()

的片段名称

 public Fragment() {
    initLifecycle();
}

错误图像外观

如果我更改它它会在 Activity 上显示错误，从我调用扫描 QR 片段的位置

Answer 1

我认为是因为你的进口

您需要将导入从 android.support.v4.app.Fragment 更改为 android.app.Fragment，反之亦然

Answer 2

您的 QRCodeFragment class 正在扩展 Fragment，哪个？（检查文件顶部的 imports）

我们有 android.app.Fragment and androidx.fragment.app.Fragment - 选择您的方法所需的适当方法

built-in android.app.Fragment 目前已弃用，您应该使用 androidx 版本，但有可能某些库仍然需要原始版本（遗憾）

Answer 3

在 onViewCreated 中，你先做你的事情然后调用 super.onViewCreated.

this 指的是 Base Fragment 实例 并且您的代码在 super[=29= 之前] 调用，它假定您的 Fragment type 是 Fragment 而不是 QRCodeFragment 解决这个

First call super.onViewCreated in onViewCreated and then do your code part

这样做-

override fun onViewCreated(view:View, savedInstanceState:Bundle? ) { super.onViewCreated(view, savedInstanceState) //your code part }

Answer 4

如果你的 QRCodeFragment 扩展 androidx.fragment.app.Fragment 那么你应该使用 IntentIntegrator.forSupportFragment

片段类型不匹配

Type Mismatched on Fragment

android

fragment

android-fragments

kotlin

android-fragmentactivity