我一直在尝试初始化UI窗口小部件，但它正在获取错误，我在互联网上查找了问题，但无法为自己的代码解决。该错误可能是由于与范围相关的某些问题而出现的，但我无法识别我的错误。
请帮帮我！非常感谢！
错误日志：
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.getroasted/com.example.android.getroasted.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.TextView.findViewById(int)' on a null object reference
片段文件
public class HomeFragment extends Fragment implements View.OnClickListener {
private static final int GALLERY_REQUEST_CODE = 1;
private static final int REQUEST_IMAGE_CAPTURE = 1;
private HomeViewModel homeViewModel;
private ImageView clickPhoto;
private ImageView addPhoto;
private ImageView photo;
private Button savePhotoButton;
private TextView roastText;
FirebaseFirestore db;
FirebaseStorage storage;
StorageReference storageRef;
String mRoastText;
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
homeViewModel =
ViewModelProviders.of(this).get(HomeViewModel.class);
View root = inflater.inflate(R.layout.fragment_home, container, false);
storage = FirebaseStorage.getInstance();
storageRef = storage.getReference();
return root;
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
roastText.findViewById(R.id.roastText);
mRoastText = roastText.getText().toString();
clickPhoto.findViewById(R.id.clickPhoto).setOnClickListener(this);
addPhoto.findViewById(R.id.clickPhoto).setOnClickListener(this);
savePhotoButton.findViewById(R.id.savePhotoButton).setOnClickListener(this);
}
片段XML文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.home.HomeFragment">
<ImageView
android:id="@+id/clickPhoto"
android:layout_width="69dp"
android:layout_height="76dp"
android:layout_alignParentStart="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="113dp"
android:layout_marginEnd="229dp"
android:layout_marginBottom="661dp"
android:src="@drawable/ic_add_a_photo_black_24dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.25"
app:layout_constraintRight_toLeftOf="@+id/addPhoto"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.5" />
<ImageView
android:id="@+id/addPhoto"
android:layout_width="69dp"
android:layout_height="76dp"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginEnd="108dp"
android:layout_marginBottom="662dp"
android:src="@drawable/ic_add_to_photos_black_24dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.701"
app:layout_constraintLeft_toRightOf="@+id/clickPhoto"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.5" />
<ImageView
android:id="@+id/photo"
android:layout_width="250dp"
android:layout_height="633dp"
android:layout_alignParentStart="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="77dp"
android:layout_marginEnd="77dp"
android:layout_marginBottom="100dp"
android:src="@drawable/image"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.669"></ImageView>
<Button
android:id="@+id/savePhotoButton"
android:layout_width="68dp"
android:layout_height="78dp"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="343dp"
android:layout_marginBottom="653dp"
android:background="@drawable/mybutton"
android:text="Save the Roast!"
android:textSize="25sp"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.585"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1" />
<!--TODO:
* Add a font
* Change size
* Add background
-->
<TextView
android:id="@+id/roastText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginEnd="177dp"
android:layout_marginBottom="250dp"
android:text="Roast"
android:textSize="35sp"
android:visibility="gone"/>
</RelativeLayout>
您正在编写的文本视图roasrText在TextView中具有
onViewCreated中的view参数是onCreateView中膨胀的片段视图，因此请使用该view参数查找您的视图
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
roastText = view.findViewById(R.id.roastText);
...