Предварительный просмотр камеры в моем приложении вызывает исключение NullPointerException

Question

Я новичок в Android Studio, и я пытаюсь сделать предварительный просмотр камеры в моем приложении, но она вызывает исключение NullPointerException.

Кажется, проблема в том, что мой SurfaceView (mSurfaceView) пустой указатель, но я не знаю, как его инициализировать.

import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.fragment.app.Fragment;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import java.io.IOException;


public class CameraFragment extends Fragment implements SurfaceHolder.Callback{

    Camera camera;

    SurfaceView mSurfaceView;
    SurfaceHolder mSurfaceHolder;

    final int CAMERA_REQUEST_CODE = 1;

    public static CameraFragment newInstance() {
        CameraFragment fragment = new CameraFragment();
        return fragment;
    }



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_camera, container, false);
        mSurfaceHolder = mSurfaceView.getHolder();

        if(ActivityCompat.checkSelfPermission(getContext(), android.Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(getActivity(), new String[] {android.Manifest.permission.CAMERA}, CAMERA_REQUEST_CODE);
        }
        else {
            mSurfaceHolder.addCallback(this);
            mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        }


        return view;
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        camera = Camera.open();

        Camera.Parameters parameters;
        parameters = camera.getParameters();

        camera.setDisplayOrientation(90);
        parameters.setPreviewFrameRate(30);
        parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);

        try {
            camera.setPreviewDisplay(holder);
        } catch (IOException e) {
            e.printStackTrace();
        }
        camera.startPreview();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode){
            case CAMERA_REQUEST_CODE: {
                if(grantResults.length>0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    mSurfaceHolder.addCallback(this);
                    mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
                }
                else{
                    Toast.makeText(getContext(), "Please provide the permission", Toast.LENGTH_LONG).show();
                }
                break;
            }
        }
    }
}

Исключение

2020-04-16 15:35:00.781 31137-31137/com.example.bouldertry E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.bouldertry, PID: 31137
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.SurfaceHolder android.view.SurfaceView.getHolder()' on a null object reference
        at com.example.bouldertry.CameraFragment.onCreateView(CameraFragment.java:42)
        at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
        at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
        at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:439)
        at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
        at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
        at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2663)
        at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java:2613)
        at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:246)
        at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:542)
        at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1435)
        at android.app.Activity.performStart(Activity.java:8014)
        at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3359)
        at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
        at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2043)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:216)
        at android.app.ActivityThread.main(ActivityThread.java:7464)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:549)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:955)