我的 SharedPreferences 是 null 。这是错误 SharedPreferences.edit() is a null object references

Question

我在我的应用程序中使用 Model View Presenter，我尝试在 SharedPreferences 中保存一个值标记。但是，我得到了 SharedPreferences null，错误是 SharedPreferences.edit() is a null object references。请帮我解决这个问题。谢谢

这是我的片段

public class SignUpFragment extends BaseFragment {

    @NotEmpty(messageResId = R.string.rules_no_empty)
    @Bind(R.id.Name)
    EditText etName;

    @NotEmpty(messageResId = R.string.rules_no_empty)
    @Bind(R.id.email)
    EditText etEmail;

    @NotEmpty(messageResId = R.string.rules_no_empty)
    @Bind(R.id.phone)
    EditText etPhone;

    @Bind(R.id.btnSignUp)
    Button btnSignUp;


    public static final String TAG = SignUpFragment.class.getSimpleName();

    private SignUpPresenter presenter;
    SharedPreferences sharedpreferences;
    public static final String MyPREFERENCES = "MyPrefs" ;

    public static void showFragment(BaseActivity sourceActivity) {
        if (!sourceActivity.isFragmentNotNull(TAG)) {
            FragmentTransaction fragmentTransaction = sourceActivity.getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.content_question, new SignUpFragment(), TAG);
            fragmentTransaction.commit();
        }
    }

    @Override
    protected int getLayout() {
        return R.layout.activity_sign_up;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        presenter = new SignUpPresenter(this);
        sharedpreferences = getActivity().getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);

    }

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


    @Override
    public void onResume() {
        super.onResume();
    }

    private void initview (){
        btnSignUp.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!validate()) {
                    onSignupFailed();
                    return;
                } else {
                    presenter.signup();
                }
            }

        });
    }

    @Override
    public void onValidationSucceeded() {
        super.onValidationSucceeded();
        presenter.signup();
    }


    public void onSignupFailed() {
        Toast.makeText(getContext(), "Login failed", Toast.LENGTH_LONG).show();

        btnSignUp.setEnabled(true);
    }


    public boolean validate() {
        boolean valid = true;

        String name = etName.getText().toString();
        String email = etEmail.getText().toString();
        String password = etPhone.getText().toString();

        if (name.isEmpty() || name.length() < 3) {
            etName.setError("at least 3 characters");
            valid = false;
        } else {
            etName.setError(null);
        }

        if (email.isEmpty() || !android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches()) {
            etEmail.setError("enter a valid email address");
            valid = false;
        }

        if (password.isEmpty() || password.length() < 4 || password.length() > 10) {
            etPhone.setError("between 4 and 10 alphanumeric characters");
            valid = false;
        } else {
            etPhone.setError(null);
        }

        return valid;
    }



    public void gotoQuestionActivity(String email, String name, String phone) {
        QuestionActivity.startActivity((BaseActivity) getActivity(), email, name, phone);
        getActivity().finish();
    }



}

这是我的主持人

public class SignUpPresenter {

    private SignUpFragment fragment;
    public String token = "token";
    SharedPreferences sharedpreferences;
    private Context mContext;
    public static final String MyPREFERENCES = "MyPrefs" ;

    public SignUpPresenter(SignUpFragment fragment) {
        this.fragment = fragment;
    }

    public SignUpRequest constructSignUpRequest() {
        SignUpRequest request = new SignUpRequest();
        request.setName(getAndTrimValueFromEditText(fragment.etName));
        request.setEmail(getAndTrimValueFromEditText(fragment.etEmail));
        request.setMobile(getAndTrimValueFromEditText(fragment.etPhone));
        return request;
    }

    private String getAndTrimValueFromEditText(EditText e) {
        return e.getText().toString().trim();
    }

    public SharedPreferences getSharedPreferences() {
        return sharedpreferences;
    }




    void signup (){
        this.register(constructSignUpRequest());
    }

    void register(final SignUpRequest signUpRequest) {
        fragment.showProgressDialog(fragment.loading);
        fragment.getApi().regsiterCustomer(constructSignUpRequest())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribeOn(Schedulers.io())
                .subscribe(new Observer<GenericResponse>() {
                    @Override
                    public void onCompleted() {

                    }

                    @Override
                    public void onError(Throwable e) {
                        fragment.dismissProgressDialog();
                        Timber.e(e.getLocalizedMessage());
                        Toast.makeText(fragment.getContext(), fragment.connectionError, Toast.LENGTH_SHORT).show();
                    }

                    @Override
                    public void onNext(GenericResponse signUpResponse) {
                        fragment.dismissProgressDialog();
                        Toast.makeText(fragment.getContext(), signUpResponse.getInfo(), Toast.LENGTH_SHORT).show();
                        if (signUpResponse.getCode() == fragment.successCode) {
                            /*fragment.gotoActivationCodeActivity(SignUpRequest.getEmail(), SignUpRequest.get());*/
                            fragment.gotoQuestionActivity(signUpRequest.getEmail(), signUpRequest.getName(), signUpRequest.getMobile());
                            SharedPreferences.Editor editor = sharedpreferences.edit();
                            editor.putString(token, signUpResponse.getData().getToken());
                            editor.commit();
                        }
                    }
                });
    }


}

Answer 1

您没有像这样在第二个 class 中定义共享首选项，就像您在第一个 class 中所做的那样。

sharedpreferences = fragment.getActivity().getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);

将此行放在代码上方，

SharedPreferences.Editor editor = sharedpreferences.edit();

在 onNext() 内部

我的 SharedPreferences 是 null 。这是错误 SharedPreferences.edit() is a null object references

My SharedPreferences is null . This is the error SharedPreferences.edit() is a null object references

android

sharedpreferences

android-sharedpreferences