我正在尝试为我的应用程序实现暗模式。我创建了两个不同的文件color.xml（第二个文件的颜色为暗模式）。我保存在布尔如果我的开关是开/关使用sharedpreferences，当我点击开关按钮颜色改变，但当我关闭我的应用程序重新打开它，返回“正常”的颜色。我处理碎片。
设置片段

public class SettingsFragment extends Fragment {

    private Context mContext;
    private SharedPreferences sharedPreferences;

    private Spinner spinner;
    private LottieAnimationView darkModeOn, darkModeOff;
    private SwitchMaterial switchDarkMode;
    private RadioButton lightRadio, darkRadio;
    private RadioGroup radioGroup;

    private boolean isDarkModeOn;
    private boolean isDarkMap;
    private Fragment fragment;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        final View v =  inflater.inflate(R.layout.settings_fragment, container, false);

        mContext = getActivity().getApplicationContext();
        fragment = getActivity().getSupportFragmentManager().findFragmentByTag(getResources().getString(R.string.settings_fragment_tag));

        spinner = v.findViewById(R.id.radius_spinner);

        darkModeOn = v.findViewById(R.id.animationDarkModeOn);
        darkModeOff = v.findViewById(R.id.animationDarkModeOff);

        radioGroup = v.findViewById(R.id.radio_group_settings);
        lightRadio = v.findViewById(R.id.light_radio);
        darkRadio = v.findViewById(R.id.dark_radio);

        switchDarkMode = v.findViewById(R.id.switch_dark_mode);

        //SharedPreferences per darkMode e darkMap
        sharedPreferences = mContext.getSharedPreferences("settingsPref", Context.MODE_PRIVATE);

        final SharedPreferences.Editor editor = sharedPreferences.edit();

        isDarkModeOn = sharedPreferences.getBoolean("darkMode",false);

        //inizializza switch e animazione
        if (!isDarkModeOn){
            darkModeOn.setVisibility(View.VISIBLE);
            switchDarkMode.setChecked(false);
        }else {
            darkModeOff.setVisibility(View.VISIBLE);
            switchDarkMode.setChecked(true);
        }

        //switch dark mode on/off and save sharedPref
        switchDarkMode.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (!isDarkModeOn){
                    isDarkModeOn = true;

                    darkModeOff.setVisibility(View.GONE);
                    darkModeOn.setVisibility(View.VISIBLE);

                    darkModeOn.playAnimation();

                    darkModeOn.addAnimatorListener(new Animator.AnimatorListener() {
                        @Override
                        public void onAnimationStart(Animator animation) {

                        }

                        @Override
                        public void onAnimationEnd(Animator animation) {
                            darkModeOn.setVisibility(View.GONE);
                            darkModeOff.setVisibility(View.VISIBLE);
                            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
                            editor.putBoolean("darkMode", true).apply();
                            MainActivity.darkModeOn = isDarkModeOn;
                        }

                        @Override
                        public void onAnimationCancel(Animator animation) {

                        }

                        @Override
                        public void onAnimationRepeat(Animator animation) {

                        }
                    });

                }else {
                    isDarkModeOn = false;

                    darkModeOn.setVisibility(View.GONE);
                    darkModeOff.setVisibility(View.VISIBLE);

                    darkModeOff.playAnimation();

                    darkModeOff.addAnimatorListener(new Animator.AnimatorListener() {
                        @Override
                        public void onAnimationStart(Animator animation) {

                        }

                        @Override
                        public void onAnimationEnd(Animator animation) {
                            darkModeOff.setVisibility(View.GONE);
                            darkModeOn.setVisibility(View.VISIBLE);
                            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
                            editor.putBoolean("darkMode", false).apply();
                            MainActivity.darkModeOn = isDarkModeOn;
                        }

                        @Override
                        public void onAnimationCancel(Animator animation) {

                        }

                        @Override
                        public void onAnimationRepeat(Animator animation) {

                        }
                    });
                }

            }
        });

        return v;
    }

}

colors.xml，夜间版本等于不同颜色

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#56ab2f</color>
    <color name="colorPrimaryDark">#56ab2f</color>
    <color name="colorAccent">#56ab2f</color>

    <!--  Color LightMode  -->
    <color name="colorChipSelected">#F44336</color>
    <color name="ghost_white">#F8F8FF</color>
    <color name="chipUnchecked">#56ab2f</color>
    <color name="white">#FFFFFF</color>
    <color name="black">#000000</color>
    <color name="defaultButtonBackgroud">#A6A6A6</color>
    <color name="dafaultTextColor">#808080</color>
    <color name="endColorGradient">#a8e063</color>
    <color name="centerColorGradient">#7FCD1F</color>
    <color name="textWhite">#FFFFFF</color>
    <color name="primaryAndWhite">#56ab2f</color>
    <color name="selectedAndWhite">#F44336</color>
    <color name="primaryAndSelected">#56ab2f</color>
    <color name="primaryAndEnd">#56ab2f</color>

    <!--  Color DarkMode  -->
    <color name="backgroundStrong">#212121</color>
    <color name="backgroundLight">#3d3d3d</color>

</resources>

mainactivity.java（oncreate）

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

        ......

        //SharedPreferences per Settings
        settingsSharedPreferences = getSharedPreferences("settingsPref", MODE_PRIVATE);
        darkModeOn = settingsSharedPreferences.getBoolean("darkMode", false);

        ......

    }

在mainactivity中，我试着写这样的东西，但没有成功：

if (!darkModeOn){
            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
        }else {
            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
        }