对于Kotlin，请尝试一下

class DataForm : Fragment() {
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        Tasks(this).getData()
    }

    fun getResponse(response: String) {
        // code
    }
}

class Tasks(private val context: Any) {
    fun getData() {

        val getContext = (context as DataForm).activity
        val getFragment = (context as DataForm)

        val responseListener = Response.Listener<String> { response ->
            getFragment.getResponse(response)
        }

        val errorListener = Response.ErrorListener { error ->
            error.printStackTrace();
        }

        val stringRequest = StringRequest(Request.Method.GET, url, responseListener, errorListener)
        Volley.newRequestQueue(getContext).add(stringRequest)
    }
}

从碎片到活动:

((YourActivityClassName)getActivity()).yourPublicMethod();

从活动到片段:

FragmentManager fm = getSupportFragmentManager();

//if you added fragment via layout xml
YourFragmentClass fragment = (YourFragmentClass)fm.findFragmentById(R.id.your_fragment_id);
fragment.yourPublicMethod();

如果你通过代码添加片段，并且在添加片段时使用了标签字符串，请使用findFragmentByTag代替:

YourFragmentClass fragment = (YourFragmentClass)fm.findFragmentByTag("yourTag");

我认为在片段初始化时传递活动实例是一个更好的方法。我像下面这样传递实例:

class FragmentSignUp : Fragment() {

    private lateinit var authActivity: AuthenticateActivity

    ...
    
    companion object {

        fun newInstance(a: AuthenticateActivity): FragmentSignUp {
            val fragment = FragmentSignUp()
            fragment.authActivity = a
            return fragment
        }
    }
}

现在，您可以使用传递的活动实例初始化片段，也可以调用活动中的任何公共方法。像下图:

val fragmentManager = supportFragmentManager
val fragment = FragmentSignUp.newInstance(this)

fragmentManager.beginTransaction().replace(R.id.authenticate_fragment, fragment, FragmentSignUp::class.java.simpleName)
            .commit()

你现在可以在你的片段中访问你的activity公共方法;就像我的例子:

authactivity.goToLogInFragment()

在Java中，你的片段类应该是:

public class FragmentSignUp extends Fragment {

    private AuthenticateActivity authActivity;

    public static FragmentSignUp newInstance(AuthenticateActivity a) {
        FragmentSignUp fragment = new FragmentSignUp();
        fragment.authActivity = a;
        return fragment;
    }
}

注意:我们也可以将活动直接注入到片段构造函数中。但在大多数情况下，我们应该避免这样做，因为它会导致一些运行时问题。

以下是我的做法:

首先制作接口

interface NavigationInterface {
    fun closeActivity()
}

接下来确保activity实现了接口并覆盖了接口方法

class NotesActivity : AppCompatActivity(), NavigationInterface {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_notes)
        setSupportActionBar(findViewById(R.id.toolbar))
    }

    override fun closeActivity() {
        this.finish()
    }
}

然后确保在片段中创建接口侦听器

private lateinit var navigationInterface: NavigationInterface

override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
): View? {
    //establish interface communication
    activity?.let {
        instantiateNavigationInterface(it)
    }
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_notes_info, container, false)
}

private fun instantiateNavigationInterface(context: FragmentActivity) {
    navigationInterface = context as NavigationInterface
}

然后你就可以这样打电话了:

view.findViewById<Button>(R.id.button_second).setOnClickListener {
    navigationInterface.closeActivity()
}

对于Kotlin，请尝试一下

class DataForm : Fragment() {
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        Tasks(this).getData()
    }

    fun getResponse(response: String) {
        // code
    }
}

class Tasks(private val context: Any) {
    fun getData() {

        val getContext = (context as DataForm).activity
        val getFragment = (context as DataForm)

        val responseListener = Response.Listener<String> { response ->
            getFragment.getResponse(response)
        }

        val errorListener = Response.ErrorListener { error ->
            error.printStackTrace();
        }

        val stringRequest = StringRequest(Request.Method.GET, url, responseListener, errorListener)
        Volley.newRequestQueue(getContext).add(stringRequest)
    }
}

对于Kotlin开发人员

(activity as YourActivityClassName).methodName()

针对Java开发人员

((YourActivityClassName) getActivity()).methodName();