"类型不匹配：推断的类型是片段，但需要上下文"和"在提供参数的情况下不能调用以下函数："

Question

package com.example.mobilewarehousesystem.ui.import

import android.Manifest
import android.content.DialogInterface
import android.content.Intent
import android.content.pm.PackageManager
import android.graphics.Bitmap
import android.os.Bundle
import android.provider.MediaStore
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.activity.result.ActivityResult
import androidx.activity.result.ActivityResultCallback
import androidx.activity.result.ActivityResultLauncher
import androidx.activity.result.contract.ActivityResultContracts
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import androidx.fragment.app.Fragment
import com.example.mobilewarehousesystem.databinding.FragmentImportBinding
import com.google.mlkit.vision.barcode.Barcode
import com.google.mlkit.vision.barcode.BarcodeScanner
import com.google.mlkit.vision.common.InputImage
import androidx.appcompat.app.AlertDialog

class ImportFragment : Fragment() {
    //show UI
    private var _binding: FragmentImportBinding?=null
    private val binding get() = _binding!!
    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
        _binding = FragmentImportBinding.inflate(inflater, container, false)
        setHasOptionsMenu(true)
        return binding.root
    }

    private val CAMERA_PERMISSION_CODE=123
    private val READ_STORAGE_PERMISSION_CODE=113
    private val WRITE_STORAGE_PERMISSION_CODE=113
    private lateinit var cameraLauncher: ActivityResultLauncher<Intent>
    private lateinit var galleryLauncher: ActivityResultLauncher<Intent>
    private val TAG = "My Tag"
    lateinit var inputImage: InputImage
    lateinit var barcodeScanner: BarcodeScanner
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        cameraLauncher = registerForActivityResult(ActivityResultContracts.StartActivityForResult(), object :ActivityResultCallback<ActivityResult>{
            override fun onActivityResult(result: ActivityResult?) {
                    val data=result?.data
                    try{
                        val photo = data?.extras?.get("data") as Bitmap
                        inputImage= InputImage.fromBitmap(photo, 0)
                        processQr()
                    }catch(e:Exception){
                        Log.d(TAG, "onActivityResult:"+e.message)
                    }
                }
            })
        galleryLauncher = registerForActivityResult(ActivityResultContracts.StartActivityForResult(), object :ActivityResultCallback<ActivityResult>{
                override fun onActivityResult(result: ActivityResult?) {
                    val data=result?.data
                    inputImage = InputImage.fromFilePath(this@ImportFragment, data?.data)
                    processQr()
                }
            })
        binding.btnScanBarcode.setOnClickListener{
            val options=arrayOf("camera","gallery")

            val builder=AlertDialog.Builder(this@ImportFragment)
            builder.setTitle("Pick a option")

            builder.setItems(options, DialogInterface.OnClickListener { dialog, which ->
                if(which==0){
                    val cameraIntent=Intent(MediaStore.ACTION_IMAGE_CAPTURE)
                    cameraLauncher.launch(cameraIntent)
                }else{
                    val storageIntent=Intent()
                    storageIntent.setType("image/*")
                    storageIntent.setAction(Intent.ACTION_GET_CONTENT)
                    galleryLauncher.launch(storageIntent)
                }
            })
            builder.show()
        }
    }
    private fun processQr(){
        binding.ivQrCode.visibility=View.GONE
        binding.tvResult.visibility=View.GONE
        barcodeScanner.process(inputImage).addOnSuccessListener{
            for (barcode:Barcode in it){
                val valueType=barcode.valueType
                when (valueType) {
                    Barcode.TYPE_WIFI -> {
                        val ssid = barcode.wifi!!.ssid
                        val password = barcode.wifi!!.password
                        val type = barcode.wifi!!.encryptionType
                        binding.tvResult.text = "ssid ${ssid} \n password ${password} \n type ${type}"
                    }
                    Barcode.TYPE_URL -> {
                        val title = barcode.url!!.title
                        val url = barcode.url!!.url
                        binding.tvResult.text = "title ${title} \n url ${url}"
                    }
                    Barcode.TYPE_TEXT->{
                        val data = barcode.displayValue
                        binding.tvResult.text="Result ${data}"
                    }
                }
            }
        }.addOnFailureListener{
            Log.d(TAG, "processQr: ${it.message}")
        }
    }
    override fun onResume() {
        super.onResume()
        checkPermission(Manifest.permission.CAMERA,CAMERA_PERMISSION_CODE)
    }
    private fun checkPermission(permission:String, requestCode:Int){
        if(ContextCompat.checkSelfPermission(this@ImportFragment, permission)== PackageManager.PERMISSION_DENIED){
            ActivityCompat.requestPermissions(this@ImportFragment, arrayOf(permission),requestCode)
        }
    }
    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)

        if(requestCode==CAMERA_PERMISSION_CODE){
            if(grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                checkPermission(
                    android.Manifest.permission.READ_EXTERNAL_STORAGE,
                    READ_STORAGE_PERMISSION_CODE)
            }else{
                Toast.makeText(this@ImportFragment, "Camera Permission Denied", Toast.LENGTH_SHORT).show()
            }
        }else if(requestCode==READ_STORAGE_PERMISSION_CODE){
            if((grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)){
                checkPermission(
                    android.Manifest.permission.WRITE_EXTERNAL_STORAGE,
                    WRITE_STORAGE_PERMISSION_CODE)
            }else{
                Toast.makeText(this@ImportFragment, "Storage Permission Denied", Toast.LENGTH_SHORT).show()
            }
        }else if(requestCode==WRITE_STORAGE_PERMISSION_CODE) {
            if (!(grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
                Toast.makeText(this@ImportFragment, "Storage Permission Denied", Toast.LENGTH_SHORT).show()
            }
        }
    }
}

我包括7个错误，都是实现错误？？这些代码是在知识有限的情况下，1比1地从主要活动转换成片段的，我找到了一些解决方案，但仍然不知道如何应用到我的代码中。

Answer 1

您必须使用上下文，而不是this@ImportFragment.

替换：

this@ImportFragment

具有

requireContext()

或者试着把

 context!!

通常，如果您编写上下文Android studio建议您将其替换为RequireText（），这里有更多详细信息：

/**
 * Return the {@link Context} this fragment is currently associated with.
 *
 * @throws IllegalStateException if not currently associated with a context.
 * @see #getContext()
 */
@NonNull
public final Context requireContext() {
    Context context = getContext();
    if (context == null) {
        throw new IllegalStateException("Fragment " + this + " not attached to a context.");
    }
    return context;
}