保存设置数据具有共享首选项，并在其他活动中使用

Question

我目前正在构建一个测验应用程序，并尝试添加设置活动，其中用户将能够管理某些游戏参数，例如声音（使用切换按钮）或游戏时间。我尝试使用共享的首选项实现它，但出现了问题：退出活动后，切换按钮的状态不会保存，并且似乎共享的偏好功能也无法正常工作。如果有人知道如何解决此问题或如何正确构建此问题，将会感到非常高兴。这是我的代码：

设置活动：

SwitchCompat switchButton;
    ImageView imageViewOn;
    private Context mContext;

public Settings(){}

public Settings(Context mContext) {
    this.mContext = mContext;
}


private String soundState;

public static final String PREFERRENCE = "shared_prefrence";
//public static final boolean TOGGLE_STATE = false;
public static final String SOUND_STATE = "sound state";
public static final String PREFERRENCE_SOUND_ON = "sound_on";
public static final String PREFERENCE_SOUND_OFF = "sound_of";

public String getSoundState() {
    return soundState;
}

public void setSoundState(String soundState) {
    this.soundState = soundState;
}

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

    switchButton = findViewById(R.id.switchButton);
    imageViewOn = findViewById(R.id.sound_on);
    loadSound();
            
switchButton.setOnCheckedChangeListener((compoundButton, b) -> {
if(compoundButton.isChecked()){
            soundState = PREFERENCE_SOUND_OFF;
            updateSoundState(soundState);
            imageViewOn.setImageResource(R.drawable.sound_off);


    }
    else{
        soundState = PREFERRENCE_SOUND_ON;
        updateSoundState(soundState);
        imageViewOn.setImageResource(R.drawable.sound_on);
    }
});
}

private void updateSoundState(String soundState) {
    SharedPreferences sharedPreferences = getSharedPreferences(PREFERRENCE,MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString(SOUND_STATE,soundState);
    editor.apply();
}

private void loadSound() {
    SharedPreferences sharedPreferences = getSharedPreferences(PREFERRENCE,MODE_PRIVATE);
    sharedPreferences.getString(SOUND_STATE, PREFERRENCE_SOUND_ON);
}

测验活动（触发声音提示的地方）添加相关代码，否则将非常长。如果缺少某些内容，请评论，我补充：

 private  Settings settings; 
 private PlayAudioForAnswers playAudioForAnswers;// class which plays audio


protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_quiz);
        setupUI();

        loadPreferences();

        playAudioForAnswers = new PlayAudioForAnswers(this);

    }

private void setupUI(){
            settings = new Settings(this);
    }


`private void loadPreferences()`
{
    
SharedPreferences sharedPreferences = getSharedPreferences(settings.PREFERRENCE, MODE_PRIVATE);
                String sound = sharedPreferences.getString(settings.SOUND_STATE,settings.PREFERRENCE_SOUND_ON);
settings.setSoundState(sound);
 }

if(settings.getSoundState().equals(settings.PREFERRENCE_SOUND_ON))
            playAudioForAnswers.setAudioforAnswer(FLAG);
 // playing the sound cue if the state is on

Answer 1

代码中的顺序错误。
首先，您应该更改声音状态，然后再保存。

    soundState = PREFERENCE_SOUND_OFF;
    updateSoundState(soundState);

相反

    updateSoundState(soundState);
    soundState = PREFERENCE_SOUND_OFF;

，您也没有调用

    soundState = PREFERRENCE_SOUND_ON;;

Answer 2

另一个工作良好的练习

您可以将pref与活动分开：

1-共享prefshelper

import android.content.Context;
import android.content.SharedPreferences;    
import static android.content.Context.MODE_PRIVATE;

/**
 * @author Islam
 * @date 10/11/2018
 */

public class SharedPrefsHelper {

    SharedPreferences mSharedPreferences;

    private static final String MY_PREFS = "YOUR_APP";
    
    public SharedPrefsHelper(Context context) {
        mSharedPreferences = context.getSharedPreferences(MY_PREFS, MODE_PRIVATE);
    }

    private static SharedPreferences getPref(Context context) {
        return context.getSharedPreferences(MY_PREFS, Context.MODE_PRIVATE);
    }

    public void clear(Context context) {
        getPref(context).edit().clear().apply();
    }
    
    /**
     * set Load all tasks
     *
     * @param isLoadAllTasks
     */
    public void setIsLoadAllTasks( boolean isLoadAllTasks) {
        mSharedPreferences.edit().putBoolean(Constants.LOAD_ALL_TASKS, isLoadAllTasks).apply();
    }

    /**
     * get Scanner Scanning
     *
     * @return
     */
    public boolean getIsLoadAllTasks() {
        return mSharedPreferences.getBoolean(Constants.LOAD_ALL_TASKS,false);

    }
    
    //endregion

}

，然后创建datamanger类是视图和数据源之间的一层（db || pref）。

2- datamanager

/**
 * @author Islam
 * @date 14/2/2020
 */
public class DataManager {

    private static final String TAG = "DataManager";

    private SharedPrefsHelper mSharedPrefsHelper;

    public DataManager(SharedPrefsHelper sharedPrefsHelper) {
        mSharedPrefsHelper = sharedPrefsHelper;
    }

    //region Settings

    /**
     * set Is Load Tasks
     *
     * @param isLoadTasks
     */
    public void setIsLoadAllTasks( boolean isLoadTasks) {
        mSharedPrefsHelper.setIsLoadAllTasks(isLoadTasks);
    }

    /**
     * get Is Load Tasks
     *
     * @return
     */
    public boolean getIsLoadAllTasks() {
        return mSharedPrefsHelper.getIsLoadAllTasks();
    }
    
    //endregion

}

3-设置活动

在ongreate中调用此事

 @Override
    protected void initUIAndActions() {
        // fetch current status 
        binding.switchLoadAll.setChecked(dataManager.getIsLoadAllTasks());
        // checking Listener
        binding.switchLoadAll.setOnCheckedChangeListener((buttonView, isChecked) -> {
            //save is Load all Tasks to Prefs
            dataManager.setIsLoadAllTasks(isChecked);
        });

    }