如何在一个片段中存储数据以在另一个片段中获取数据？

Question

I am storing a string in my shared preference class and I want to use this String in another fragment.

I think I am doing something wrong with the Context, Application Context. I did not know about the context thing. Whenever I open my Profile Fragment the app crashes.

Shared Preference Class

public class SharedPrefs {
private static final String myPrefs = "myprefs";
private static final String LogedInKey = "Key";
private final Context context;
private final SharedPreferences sharedPreferences;
private final SharedPreferences.Editor editor;


public SharedPrefs(Context context) {
    this.context = context;
    sharedPreferences = context.getSharedPreferences(myPrefs, Context.MODE_PRIVATE);
    editor = sharedPreferences.edit();
}

public void savePref(String key) {
    editor.putString(LogedInKey, key);
    editor.commit();
}

public String getLogedInKey() {
    return sharedPreferences.getString(LogedInKey, null);
}

public void clearLogin() {
    editor.putString(LogedInKey, null);
    editor.commit();
}}

My Profile Fragment:

public class ProfileFragment extends Fragment {
private Context context;
private SharedPrefs sharedPrefs=new SharedPrefs(context);

public ProfileFragment(Context context) {
    this.context = context;
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_profile, null);
    TextView userName=view.findViewById(R.id.userName);
    String a=sharedPrefs.getLogedInKey();
    userName.setText(a);

    return view;
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);


}}

I just want to set the string to the TextView from the shared reference.

Answer 1

1.Actually you don't need to pass context as fragment constructor cause that is not right and it will not work

    public class ProfileFragment extends Fragment {
    private SharedPrefs sharedPrefs;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                     Bundle savedInstanceState) {
    sharedPrefs=new SharedPrefs(getActivity());
    View view = inflater.inflate(R.layout.fragment_profile, null);
    TextView userName=view.findViewById(R.id.userName);
    String a=sharedPrefs.getLogedInKey();
    userName.setText(a);

      return view;
    }
    @Override

    public void onViewCreated(@NonNull View view, @Nullable Bundle                  
    savedInstanceState) {
   super.onViewCreated(view, savedInstanceState);

   }}

Answer 2

Try using

In onCreateView()

context = getActivity().getApplicationContext();

Answer 3

define your sharedpreference in the constructor:

public ProfileFragment(Context context) {
this.context = context;
sharedPrefs=new SharedPrefs(context);
}

And be sure you save something with the key LogedInKey