你可以在片段中创建一个setter方法。然后在Activity中，当引用片段时，调用setter方法并将Activity中的数据传递给它

我在使用最新的导航体系结构组件时遇到了类似的问题。通过从我的调用活动传递一个包到Fragment，尝试了上述所有代码。

紧跟Android最新发展趋势的最佳解决方案是使用View Model (Android Jetpack的一部分)。

在父Activity中创建并初始化一个ViewModel类，请注意这个ViewModel必须在Activity和fragment之间共享。

现在，在片段的onViewCreated()中，初始化相同的ViewModel并设置观察者来监听ViewModel字段。

如果你需要，这里有一个有用的，深入的教程。

https://medium.com/mindorks/how-to-communicate-between-fragments-and-activity-using-viewmodel-ca733233a51c

你也可以从片段访问活动数据:

活动:

public class MyActivity extends Activity {

    private String myString = "hello";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
        ...
    }

    public String getMyData() {
        return myString;
    }
}

片段:

public class MyFragment extends Fragment {

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

        MyActivity activity = (MyActivity) getActivity();
        String myDataFromActivity = activity.getMyData();
        return view;
    }
}

我在这里@ stackoverflow.com找到了很多答案，但这绝对是正确的答案:

“发送数据从活动碎片在android”。

活动:

        Bundle bundle = new Bundle();
        String myMessage = "Stackoverflow is cool!";
        bundle.putString("message", myMessage );
        FragmentClass fragInfo = new FragmentClass();
        fragInfo.setArguments(bundle);
        transaction.replace(R.id.fragment_single, fragInfo);
        transaction.commit();

片段:

读取片段中的值

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        Bundle bundle = this.getArguments();
        String myValue = bundle.getString("message");
        ...
        ...
        ...
        }

或者只是

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        String myValue = this.getArguments().getString("message");
        ...
        ...
        ...
        }

从Activity中发送数据，意图如下:

Bundle bundle = new Bundle();
bundle.putString("edttext", "From Activity");
// set Fragmentclass Arguments
Fragmentclass fragobj = new Fragmentclass();
fragobj.setArguments(bundle);

在Fragment的onCreateView方法中:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    String strtext = getArguments().getString("edttext");    
    return inflater.inflate(R.layout.fragment, container, false);
}

Very old post, still I dare to add a little explanation that would had been helpful for me. Technically you can directly set members of any type in a fragment from activity. So why Bundle? The reason is very simple - Bundle provides uniform way to handle:-- creating/opening fragment -- reconfiguration (screen rotation) - just add initial/updated bundle to outState in onSaveInstanceState() -- app restoration after being garbage collected in background (as with reconfiguration). You can (if you like experiments) create a workaround in simple situations but Bundle-approach just doesn't see difference between one fragment and one thousand on a backstack - it stays simple and straightforward. That's why the answer by @Elenasys is the most elegant and universal solution. And that's why the answer given by @Martin has pitfalls