Java 从活动调用片段视图中的按钮

我想访问Activity方法中的片段项，但得到一个空指针错误

片段类

 Button button;

 public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

      final View view = inflater.inflate(R.layout.fragment, container, false);
      button= view.findViewById(R.id.button);

    return view;
    }

    public Button getButton(){
            return button;
    }

main活动

FragmentManager fm = getSupportFragmentManager();
Fragment fragment = (Fragment)fm.findFragmentById(R.id.Framelayout);

fragment.getButton().setText("Test");

LOGCAT

 java.lang.NullPointerException: Attempt to invoke virtual method 
 'android.widget.Button com.example.android.fragment.Fragment.getButton()' 
 on a null object reference
        at 
 com.example.android.MainActivity$1$1.onDataChange(MainActivity.java:141)

---

尝试使用getFragmentManager（）而不是getSupportFragmentManager（）来添加片段

private void addFragment(FragmentManager manager)
{
    YOURFRAGMENT fragment= new YOURFRAGMENT();
    FragmentTransaction transaction=manager.beginTransaction();
    transaction.add(CONTAINER-ID,fragment,YOURFRAGMENT.class.getSimpleName()).commitNow();
}

 private void getFragment(FragmentManager manager,String TAG){
          YOURFRAGMENT fragment= (YOURFRAGMENT) manager.findFragmentByTag(TAG);
       if(fragment!=null){
       //access button here
       }
}

为了得到碎片

private void addFragment(FragmentManager manager)
{
    YOURFRAGMENT fragment= new YOURFRAGMENT();
    FragmentTransaction transaction=manager.beginTransaction();
    transaction.add(CONTAINER-ID,fragment,YOURFRAGMENT.class.getSimpleName()).commitNow();
}

 private void getFragment(FragmentManager manager,String TAG){
          YOURFRAGMENT fragment= (YOURFRAGMENT) manager.findFragmentByTag(TAG);
       if(fragment!=null){
       //access button here
       }
}

得到你的

getFragment(fragmentManager, YOURFRAGMENT.class.getSimpleName())k

---

使用

标记添加
片段

String TAG="YourTAG";
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
        .replace(R.id.fragment_container, mFragment, TAG)
        .commit();

您可以像这样从活动中调用方法

Fragment fragment = getSupportFragmentManager().findFragmentByTag(TAG);
if (fragment instanceof YourFragmentClass ) {
    fragment.getButton().setText("Test");
}

希望对您有所帮助。
您是如何附加该片段的？我不知道您的确切意思。意思是您在添加片段时添加了标记吗？否，我没有添加。我将发布有关此GetFragmentManager（）不推荐使用的答案。在哪里。你收到这个了吗？是的。MainActivity.class。请调用
fragment.getButton（）。findFragmentByTag（“片段”）；如果（AnaSayfa的片段实例）{fragment.getButton（）.setText（“Test”）；}无法解析方法“getButton（）”其中//访问此处的按钮