我的目标是从一个Fragment访问MainActivity的ProgressBar和TextView。然而,我收到以下错误提示:
“尝试在null对象引用上调用虚拟方法'void android.widget.ProgressBar.setVisibility(int)'”
activity_main.xml
activity_main.xml
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="200dp"
android:orientation="vertical"
android:layout_gravity="center">
<ProgressBar
android:id="@+id/pbLoading"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:indeterminate="true"
android:layout_gravity="center"
android:visibility="visible"/>
<TextView
android:id="@+id/tvLoading"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="@dimen/dimension_8dp"
android:fontFamily="@font/robotomedium"
android:textSize="16sp"
android:visibility="visible"
android:text="@string/loading_text"/>
</LinearLayout>
SampleFragment.java
@Override
public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
fragmentDataBinding = DataBindingUtil.inflate(inflater, R.layout.fragment_currency_list, container, false);
return Objects.requireNonNull(fragmentDataBinding).getRoot();
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
mPbLoading = fragmentDataBinding.getRoot().findViewById(R.id.pbLoading);
mPbLoading.setVisibility(View.GONE);
}
我曾试图篡改很多帖子和文章,但都没有成功。提前感谢您。
祝好,