07-19 03:36:38.068 4150-4150/com.example.developer_4.testproject E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.developer_4.testproject, PID: 4150
    java.lang.ClassCastException: android.app.NotificationManager cannot be cast to android.content.Context
        at com.example.developer_4.testproject.First$1.onClick(First.java:42)
        at android.view.View.performClick(View.java:5637)
        at android.view.View$PerformClick.run(View.java:22429)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6119)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

public class First extends Fragment {
    Button notification;
    private NotificationManager nm;
    private final int NOTIFICATION_ID = 127;


    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_first, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        notification = view.findViewById(R.id.button3);

        nm = (NotificationManager) Objects.requireNonNull(getActivity()).getSystemService(NOTIFICATION_SERVICE);
        notification.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Notification.Builder builder = new Notification.Builder((Context) (getActivity()).getSystemService(NOTIFICATION_SERVICE));
                //PendingIntent pendingIntent = new PendingIntent.getActivity(getActivity().getCo);
                builder
                        //.setContentIntent(new PendingIntent())
                        .setSmallIcon(R.drawable.ic_android_black_24dp)
                        .setLargeIcon(BitmapFactory.decodeResource(getActivity().getResources(),R.drawable.ic_android_black_24dp))
                        .setTicker("Test notification")
                        .setWhen(System.currentTimeMillis())
                        .setAutoCancel(true)
                        .setContentTitle("Notification")
                        .setContentText("Press please");

                Notification notification = builder.build();
                nm.notify(NOTIFICATION_ID,notification);
                Toast.makeText(getContext(), "1", Toast.LENGTH_SHORT).show();
            }
        });
    }
}